diff --git a/Cargo.toml b/Cargo.toml index 3c77bf8..b558956 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -4,6 +4,7 @@ members = [ "imgui-sys", "imgui-gfx-renderer", "imgui-glium-renderer", + "imgui-glow-renderer", "imgui-winit-support", "imgui-examples", "imgui-gfx-examples", diff --git a/imgui-glow-renderer/Cargo.toml b/imgui-glow-renderer/Cargo.toml new file mode 100644 index 0000000..4a97636 --- /dev/null +++ b/imgui-glow-renderer/Cargo.toml @@ -0,0 +1,49 @@ +[package] +name = "imgui-glow-renderer" +version = "0.7.0" +edition = "2018" +authors = ["The imgui-rs Developers"] +description = "glow renderer for the imgui crate" +homepage = "https://github.com/imgui-rs/imgui-rs" +repository = "https://github.com/imgui-rs/imgui-rs" +license = "MIT/Apache-2.0" +categories = ["gui", "rendering"] + +[dependencies] +imgui = { version = "0.7.0", path = "../imgui" } +glow = "0.10.0" +memoffset = "0.6.4" + +[dev-dependencies] +glutin = "0.26.0" +imgui-winit-support = { version = "0.7.1", path = "../imgui-winit-support" } + +[features] +# Features here are used to opt-out of compiling code that depends on certain +# OpenGL features. If the features are enabled, the renderer will check that the +# feature is supported before attempting to use it. Only opt-out of any of these +# if you are certain you will only target platforms that lack the corresponding +# feature. +default = [ + "gl_extensions_support", + "bind_vertex_array_support", + "vertex_offset_support", + "clip_origin_support", + "bind_sampler_support", + "polygon_mode_support", + "primitive_restart_support", +] +# Enable checking for OpenGL extensions +gl_extensions_support = [] +# Support for `glBindVertexArray` +bind_vertex_array_support = [] +# Support for `glDrawElementsBaseVertex` +vertex_offset_support = [] +# Support for `GL_CLIP_ORIGIN` +clip_origin_support = [] +# Support for `glBindSampler` +bind_sampler_support = [] +# Support for `glPolygonMode` +polygon_mode_support = [] +# Support for `GL_PRIMITIVE_RESTART` +primitive_restart_support = [] diff --git a/imgui-glow-renderer/LICENSE-APACHE b/imgui-glow-renderer/LICENSE-APACHE new file mode 100644 index 0000000..8f71f43 --- /dev/null +++ b/imgui-glow-renderer/LICENSE-APACHE @@ -0,0 +1,202 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. 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IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. diff --git a/imgui-glow-renderer/examples/basic.rs b/imgui-glow-renderer/examples/basic.rs new file mode 100644 index 0000000..239360a --- /dev/null +++ b/imgui-glow-renderer/examples/basic.rs @@ -0,0 +1,116 @@ +//! A basic self-contained example to get you from zero-to-demo-window as fast +//! as possible. + +use std::time::Instant; + +use glow::HasContext; +use glutin::{event_loop::EventLoop, WindowedContext}; +use imgui_winit_support::WinitPlatform; + +const TITLE: &str = "Hello, imgui-rs!"; + +type Window = WindowedContext; + +fn main() { + // Common setup for creating a winit window and imgui context, not specifc + // to this renderer at all ecept that glutin is used to create the window + // since it will give us access to a GL context + let (event_loop, window) = create_window(); + let (mut winit_platform, mut imgui_context) = imgui_init(&window); + + // OpenGL context from glow + let gl = glow_context(&window); + unsafe { gl.clear_color(0.05, 0.05, 0.1, 1.0) }; + + // OpenGL renderer from this crate + let mut ig_renderer = imgui_glow_renderer::auto_renderer(gl, &mut imgui_context) + .expect("failed to create renderer"); + + // Standard winit event loop + let mut last_frame = Instant::now(); + event_loop.run(move |event, _, control_flow| { + *control_flow = glutin::event_loop::ControlFlow::Wait; + match event { + glutin::event::Event::NewEvents(_) => { + let now = Instant::now(); + imgui_context + .io_mut() + .update_delta_time(now.duration_since(last_frame)); + last_frame = now; + } + glutin::event::Event::MainEventsCleared => { + winit_platform + .prepare_frame(imgui_context.io_mut(), window.window()) + .unwrap(); + window.window().request_redraw(); + } + glutin::event::Event::RedrawRequested(_) => { + // The renderer assumes you'll be clearing the buffer yourself + unsafe { ig_renderer.gl_context().clear(glow::COLOR_BUFFER_BIT) }; + + let ui = imgui_context.frame(); + ui.show_demo_window(&mut true); + + winit_platform.prepare_render(&ui, window.window()); + let draw_data = ui.render(); + + // This is the only extra render step to add + ig_renderer + .render(&draw_data) + .expect("error rendering imgui"); + + window.swap_buffers().unwrap(); + } + glutin::event::Event::WindowEvent { + event: glutin::event::WindowEvent::CloseRequested, + .. + } => { + *control_flow = glutin::event_loop::ControlFlow::Exit; + } + event => { + winit_platform.handle_event(imgui_context.io_mut(), window.window(), &event); + } + } + }); +} + +fn create_window() -> (EventLoop<()>, Window) { + let event_loop = glutin::event_loop::EventLoop::new(); + let window = glutin::window::WindowBuilder::new() + .with_title(TITLE) + .with_inner_size(glutin::dpi::LogicalSize::new(1024, 768)); + let window = glutin::ContextBuilder::new() + .with_vsync(true) + .build_windowed(window, &event_loop) + .expect("could not create window"); + let window = unsafe { + window + .make_current() + .expect("could not make window context current") + }; + (event_loop, window) +} + +fn glow_context(window: &Window) -> glow::Context { + unsafe { glow::Context::from_loader_function(|s| window.get_proc_address(s).cast()) } +} + +fn imgui_init(window: &Window) -> (WinitPlatform, imgui::Context) { + let mut imgui_context = imgui::Context::create(); + imgui_context.set_ini_filename(None); + + let mut winit_platform = WinitPlatform::init(&mut imgui_context); + winit_platform.attach_window( + imgui_context.io_mut(), + window.window(), + imgui_winit_support::HiDpiMode::Rounded, + ); + + imgui_context + .fonts() + .add_font(&[imgui::FontSource::DefaultFontData { config: None }]); + + imgui_context.io_mut().font_global_scale = (1.0 / winit_platform.hidpi_factor()) as f32; + + (winit_platform, imgui_context) +} diff --git a/imgui-glow-renderer/src/lib.rs b/imgui-glow-renderer/src/lib.rs new file mode 100644 index 0000000..98173df --- /dev/null +++ b/imgui-glow-renderer/src/lib.rs @@ -0,0 +1,1269 @@ +use std::{borrow::Cow, error::Error, fmt::Display, marker::PhantomData, mem::size_of}; + +use imgui::{internal::RawWrapper, TextureId}; + +use crate::versions::{GlVersion, GlslVersion}; + +pub mod versions; + +// TODO: document all the things! + +// This may be generics overkill, but I have to assume there's some reason that +// `glow` hid the functions of `Context` behind the `HasContext` trait. The +// specified types I require here are necessary because otherwise I can't +// perform the required initialisations or conversions in the code below. In +// any case, the OpenGL standard specifies these types, so there should be no +// loss of generality. +pub trait Gl: + glow::HasContext< + Texture = glow::Texture, + UniformLocation = glow::UniformLocation, + Program = glow::Program, + Buffer = glow::Buffer, + Sampler = glow::Sampler, + VertexArray = glow::VertexArray, +> +{ +} +impl< + G: glow::HasContext< + Texture = glow::Texture, + UniformLocation = glow::UniformLocation, + Program = glow::Program, + Buffer = glow::Buffer, + Sampler = glow::Sampler, + VertexArray = glow::VertexArray, + >, + > Gl for G +{ +} + +/// Convenience function to get you going quickly. In most larger programs +/// you probably want to take more control (including ownership of the GL +/// context). In those cases, construct an appropriate renderer with +/// `RendererBuilder`. +pub fn auto_renderer( + gl: G, + imgui_context: &mut imgui::Context, +) -> Result, StateBackupCsm>, InitError> +{ + RendererBuilder::new() + .with_context_state_manager(StateBackupCsm::default()) + .build_owning(gl, imgui_context) +} + +pub struct RendererBuilder +where + G: Gl, + T: TextureMap, + S: ShaderProvider, + C: ContextStateManager, +{ + texture_map: T, + shader_provider: S, + context_state_manager: C, + phantom_gl: PhantomData, +} + +impl RendererBuilder, TrivialCsm> { + #[allow(clippy::new_without_default)] + #[must_use] + pub fn new() -> Self { + Self { + texture_map: TrivialTextureMap(), + shader_provider: as Default>::default(), + context_state_manager: TrivialCsm(), + phantom_gl: PhantomData::default(), + } + } +} + +impl RendererBuilder +where + G: Gl, + T: TextureMap, + S: ShaderProvider, + C: ContextStateManager, +{ + pub fn with_texture_map(self, texture_map: T2) -> RendererBuilder { + RendererBuilder { + texture_map, + shader_provider: self.shader_provider, + context_state_manager: self.context_state_manager, + phantom_gl: self.phantom_gl, + } + } + + pub fn with_shader_provider>( + self, + shader_provider: S2, + ) -> RendererBuilder { + RendererBuilder { + texture_map: self.texture_map, + shader_provider, + context_state_manager: self.context_state_manager, + phantom_gl: self.phantom_gl, + } + } + + pub fn with_context_state_manager>( + self, + context_state_manager: C2, + ) -> RendererBuilder { + RendererBuilder { + texture_map: self.texture_map, + shader_provider: self.shader_provider, + context_state_manager, + phantom_gl: self.phantom_gl, + } + } + + pub fn build_owning( + self, + gl: G, + imgui_context: &mut imgui::Context, + ) -> Result, InitError> { + let renderer = self.build_borrowing(&gl, imgui_context)?; + Ok(OwningRenderer:: { gl, renderer }) + } + + pub fn build_borrowing( + self, + gl: &G, + imgui_context: &mut imgui::Context, + ) -> Result, InitError> { + Renderer::::initialize( + gl, + imgui_context, + self.texture_map, + self.shader_provider, + self.context_state_manager, + ) + } +} + +// TODO: builder pattern +/// Renderer which owns the OpenGL context. Useful for simple applications, but +/// more complicated applications may prefer to keep control of their own +/// OpenGL context, or even change that context at runtime. +/// +/// OpenGL context is still available to the rest of the application through +/// the `gl_context` method. +pub struct OwningRenderer, C = TrivialCsm> +where + G: Gl, + T: TextureMap, + S: ShaderProvider, + C: ContextStateManager, +{ + gl: G, + renderer: Renderer, +} + +impl OwningRenderer +where + G: Gl, + T: TextureMap, + S: ShaderProvider, + C: ContextStateManager, +{ + /// Note: no need to provide a `mut` version of this, as all methods on + /// `glow::HasContext` are immutable. + #[inline] + pub fn gl_context(&self) -> &G { + &self.gl + } + + #[inline] + pub fn renderer(&self) -> &Renderer { + &self.renderer + } + + /// # Errors + /// Some OpenGL errors trigger an error (few are explicitly checked, + /// however) + #[inline] + pub fn render(&mut self, draw_data: &imgui::DrawData) -> Result<(), RenderError> { + self.renderer.render(&self.gl, draw_data) + } +} + +impl Drop for OwningRenderer +where + G: Gl, + T: TextureMap, + S: ShaderProvider, + C: ContextStateManager, +{ + fn drop(&mut self) { + self.renderer.destroy(&self.gl); + } +} + +pub struct Renderer, C = TrivialCsm> +where + G: Gl, + T: TextureMap, + S: ShaderProvider, + C: ContextStateManager, +{ + pub texture_map: T, + pub shader_provider: S, + pub context_state_manager: C, + pub vbo_handle: G::Buffer, + pub ebo_handle: G::Buffer, + pub font_atlas_texture: G::Texture, + #[cfg(feature = "bind_vertex_array_support")] + pub vertex_array_object: G::VertexArray, + pub gl_version: GlVersion, + pub has_clip_origin_support: bool, + pub is_destroyed: bool, +} + +impl Renderer +where + G: Gl, + T: TextureMap, + S: ShaderProvider, + C: ContextStateManager, +{ + /// # Errors + /// Any error initialising the OpenGL objects (including shaders) will + /// result in an error. + pub fn initialize( + gl: &G, + imgui_context: &mut imgui::Context, + texture_map: T, + shader_provider: S, + context_state_manager: C, + ) -> Result { + #![allow( + clippy::similar_names, + clippy::cast_sign_loss, + clippy::shadow_unrelated + )] + + let gl_version = GlVersion::read(gl); + + #[cfg(feature = "clip_origin_support")] + let has_clip_origin_support = { + let support = gl_version.clip_origin_support(); + + #[cfg(feature = "gl_extensions_support")] + if support { + support + } else { + let extensions_count = unsafe { gl.get_parameter_i32(glow::NUM_EXTENSIONS) } as u32; + (0..extensions_count).any(|index| { + let extension_name = + unsafe { gl.get_parameter_indexed_string(glow::EXTENSIONS, index) }; + extension_name == "GL_ARB_clip_control" + }) + } + #[cfg(not(feature = "gl_extensions_support"))] + support + }; + #[cfg(not(feature = "clip_origin_support"))] + let has_clip_origin_support = false; + + let mut context_state_manager = context_state_manager; + context_state_manager.pre_init(gl, gl_version)?; + + let font_atlas_texture = prepare_font_atlas(gl, imgui_context.fonts())?; + + let mut shader_provider = shader_provider; + shader_provider.initialize(gl, gl_version)?; + let vbo_handle = unsafe { gl.create_buffer() }.map_err(InitError::CreateBufferObject)?; + let ebo_handle = unsafe { gl.create_buffer() }.map_err(InitError::CreateBufferObject)?; + + context_state_manager.post_init(gl, gl_version)?; + + let out = Self { + texture_map, + shader_provider, + context_state_manager, + vbo_handle, + ebo_handle, + font_atlas_texture, + #[cfg(feature = "bind_vertex_array_support")] + vertex_array_object: 0, + gl_version, + has_clip_origin_support, + is_destroyed: false, + }; + + // Leave this until the end of the function to avoid changing state if + // there was ever an error above + out.configure_imgui_context(imgui_context); + + Ok(out) + } + + pub fn destroy(&mut self, gl: &G) { + if self.is_destroyed { + return; + } + + let gl_version = self.gl_version; + self.context_state_manager.pre_destroy(gl, gl_version); + + if self.vbo_handle != 0 { + unsafe { gl.delete_buffer(self.vbo_handle) }; + self.vbo_handle = 0; + } + if self.ebo_handle != 0 { + unsafe { gl.delete_buffer(self.vbo_handle) }; + self.ebo_handle = 0; + } + let program = self.shader_provider.data().program; + if program != 0 { + unsafe { gl.delete_program(program) }; + } + if self.font_atlas_texture != 0 { + unsafe { gl.delete_texture(self.font_atlas_texture) }; + self.font_atlas_texture = 0; + } + + self.context_state_manager.post_destroy(gl, gl_version); + + self.is_destroyed = true; + } + + /// # Errors + /// Some OpenGL errors trigger an error (few are explicitly checked, + /// however) + pub fn render(&mut self, gl: &G, draw_data: &imgui::DrawData) -> Result<(), RenderError> { + if self.is_destroyed { + return Err(Self::renderer_destroyed()); + } + + let fb_width = draw_data.display_size[0] * draw_data.framebuffer_scale[0]; + let fb_height = draw_data.display_size[1] * draw_data.framebuffer_scale[1]; + if !(fb_width > 0.0 && fb_height > 0.0) { + return Ok(()); + } + + gl_debug_message(gl, "imgui-rs-glow: start render"); + self.context_state_manager.pre_render(gl, self.gl_version)?; + + self.set_up_render_state(gl, draw_data, fb_width, fb_height)?; + + gl_debug_message(gl, "start loop over draw lists"); + for draw_list in draw_data.draw_lists() { + unsafe { + gl.buffer_data_u8_slice( + glow::ARRAY_BUFFER, + to_byte_slice(draw_list.vtx_buffer()), + glow::STREAM_DRAW, + ); + gl.buffer_data_u8_slice( + glow::ELEMENT_ARRAY_BUFFER, + to_byte_slice(draw_list.idx_buffer()), + glow::STREAM_DRAW, + ); + } + + gl_debug_message(gl, "start loop over commands"); + for command in draw_list.commands() { + match command { + imgui::DrawCmd::Elements { count, cmd_params } => { + self.render_elements(gl, count, cmd_params, draw_data, fb_width, fb_height) + } + imgui::DrawCmd::RawCallback { callback, raw_cmd } => unsafe { + callback(draw_list.raw(), raw_cmd) + }, + imgui::DrawCmd::ResetRenderState => { + self.set_up_render_state(gl, draw_data, fb_width, fb_height)? + } + } + } + } + + #[cfg(feature = "bind_vertex_array_support")] + if self.gl_version.bind_vertex_array_support() { + unsafe { gl.delete_vertex_array(self.vertex_array_object) }; + } + + self.context_state_manager + .post_render(gl, self.gl_version)?; + gl_debug_message(gl, "imgui-rs-glow: complete render"); + Ok(()) + } + + /// # Errors + /// Few GL calls are checked for errors, but any that are found will result + /// in an error. Errors from the state manager lifecycle callbacks will also + /// result in an error. + pub fn set_up_render_state( + &mut self, + gl: &G, + draw_data: &imgui::DrawData, + fb_width: f32, + fb_height: f32, + ) -> Result<(), RenderError> { + #![allow(clippy::cast_possible_truncation, clippy::cast_possible_wrap)] + + if self.is_destroyed { + return Err(Self::renderer_destroyed()); + } + + self.context_state_manager + .pre_setup_render(gl, self.gl_version)?; + + unsafe { + gl.active_texture(glow::TEXTURE0); + gl.enable(glow::BLEND); + gl.blend_equation(glow::FUNC_ADD); + gl.blend_func_separate( + glow::SRC_ALPHA, + glow::ONE_MINUS_SRC_ALPHA, + glow::ONE, + glow::ONE_MINUS_SRC_ALPHA, + ); + gl.disable(glow::CULL_FACE); + gl.disable(glow::DEPTH_TEST); + gl.disable(glow::STENCIL_TEST); + gl.enable(glow::SCISSOR_TEST); + + #[cfg(feature = "primitive_restart_support")] + if self.gl_version.primitive_restart_support() { + gl.disable(glow::PRIMITIVE_RESTART); + } + + #[cfg(feature = "polygon_mode_support")] + if self.gl_version.polygon_mode_support() { + gl.polygon_mode(glow::FRONT_AND_BACK, glow::FILL); + } + + gl.viewport(0, 0, fb_width as _, fb_height as _); + } + + #[cfg(feature = "clip_origin_support")] + let clip_origin_is_lower_left = if self.has_clip_origin_support { + unsafe { gl.get_parameter_i32(glow::CLIP_ORIGIN) != glow::UPPER_LEFT as i32 } + } else { + true + }; + #[cfg(not(feature = "clip_origin_support"))] + let clip_origin_is_lower_left = true; + + let projection_matrix = calculate_matrix(draw_data, clip_origin_is_lower_left); + let shader_data = self.shader_provider.data(); + + unsafe { + gl.use_program(Some(shader_data.program)); + gl.uniform_1_i32(Some(&shader_data.texture_uniform_location), 0); + gl.uniform_matrix_4_f32_slice( + Some(&shader_data.matrix_uniform_location), + false, + &projection_matrix, + ); + } + + #[cfg(feature = "bind_sampler_support")] + if self.gl_version.bind_sampler_support() { + unsafe { gl.bind_sampler(0, None) }; + } + + #[cfg(feature = "bind_vertex_array_support")] + if self.gl_version.bind_vertex_array_support() { + unsafe { + self.vertex_array_object = gl + .create_vertex_array() + .map_err(|err| format!("Error creating vertex array object: {}", err))?; + gl.bind_vertex_array(Some(self.vertex_array_object)); + } + } + + // TODO: soon it should be possible for these to be `const` functions + let position_field_offset = memoffset::offset_of!(imgui::DrawVert, pos) as _; + let uv_field_offset = memoffset::offset_of!(imgui::DrawVert, uv) as _; + let color_field_offset = memoffset::offset_of!(imgui::DrawVert, col) as _; + + unsafe { + gl.bind_buffer(glow::ARRAY_BUFFER, Some(self.vbo_handle)); + gl.bind_buffer(glow::ELEMENT_ARRAY_BUFFER, Some(self.ebo_handle)); + gl.enable_vertex_attrib_array(shader_data.position_attribute_index); + gl.vertex_attrib_pointer_f32( + shader_data.position_attribute_index, + 2, + glow::FLOAT, + false, + size_of::() as _, + position_field_offset, + ); + gl.enable_vertex_attrib_array(shader_data.uv_attribute_index); + gl.vertex_attrib_pointer_f32( + shader_data.uv_attribute_index, + 2, + glow::FLOAT, + false, + size_of::() as _, + uv_field_offset, + ); + gl.enable_vertex_attrib_array(shader_data.color_attribute_index); + gl.vertex_attrib_pointer_f32( + shader_data.color_attribute_index, + 4, + glow::UNSIGNED_BYTE, + true, + size_of::() as _, + color_field_offset, + ); + } + + self.context_state_manager + .post_setup_render(gl, self.gl_version) + } + + fn render_elements( + &self, + gl: &G, + element_count: usize, + element_params: imgui::DrawCmdParams, + draw_data: &imgui::DrawData, + fb_width: f32, + fb_height: f32, + ) { + #![allow( + clippy::similar_names, + clippy::cast_possible_truncation, + clippy::cast_possible_wrap + )] + + let imgui::DrawCmdParams { + clip_rect, + texture_id, + vtx_offset, + idx_offset, + } = element_params; + let clip_off = draw_data.display_pos; + let scale = draw_data.framebuffer_scale; + + let clip_x1 = (clip_rect[0] - clip_off[0]) * scale[0]; + let clip_y1 = (clip_rect[1] - clip_off[1]) * scale[1]; + let clip_x2 = (clip_rect[2] - clip_off[0]) * scale[0]; + let clip_y2 = (clip_rect[3] - clip_off[1]) * scale[1]; + + if clip_x1 >= fb_width || clip_y1 >= fb_height || clip_x2 < 0.0 || clip_y2 < 0.0 { + return; + } + + unsafe { + gl.scissor( + clip_x1 as i32, + (fb_height - clip_y2) as i32, + (clip_x2 - clip_x1) as i32, + (clip_y2 - clip_y1) as i32, + ); + gl.bind_texture(glow::TEXTURE_2D, self.texture_map.gl_texture(texture_id)); + + #[cfg(feature = "vertex_offset_support")] + let with_offset = self.gl_version.vertex_offset_support(); + #[cfg(not(feature = "vertex_offset_support"))] + let with_offset = false; + + if with_offset { + gl.draw_elements_base_vertex( + glow::TRIANGLES, + element_count as _, + imgui_index_type_as_gl(), + (idx_offset * size_of::()) as _, + vtx_offset as _, + ); + } else { + gl.draw_elements( + glow::TRIANGLES, + element_count as _, + imgui_index_type_as_gl(), + (idx_offset * size_of::()) as _, + ); + } + } + } + + fn configure_imgui_context(&self, imgui_context: &mut imgui::Context) { + imgui_context.set_renderer_name(Some( + format!("imgui-rs-glow-render {}", env!("CARGO_PKG_VERSION")).into(), + )); + + #[cfg(feature = "vertex_offset_support")] + if self.gl_version.vertex_offset_support() { + imgui_context + .io_mut() + .backend_flags + .insert(imgui::BackendFlags::RENDERER_HAS_VTX_OFFSET); + } + } + + fn renderer_destroyed() -> RenderError { + "Renderer is destroyed".into() + } +} + +pub trait TextureMap { + fn gl_texture(&self, imgui_texture: imgui::TextureId) -> Option; +} + +pub struct TrivialTextureMap(); + +impl TextureMap for TrivialTextureMap { + fn gl_texture(&self, imgui_texture: imgui::TextureId) -> Option { + #[allow(clippy::cast_possible_truncation)] + Some(imgui_texture.id() as _) + } +} + +pub trait ContextStateManager { + #![allow(unused_variables, clippy::missing_errors_doc)] + + fn pre_init(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), InitError> { + Ok(()) + } + + fn post_init(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), InitError> { + Ok(()) + } + + fn pre_render(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), RenderError> { + Ok(()) + } + + fn pre_setup_render(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), RenderError> { + Ok(()) + } + + fn post_setup_render(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), RenderError> { + Ok(()) + } + + fn post_render(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), RenderError> { + Ok(()) + } + + fn pre_destroy(&mut self, gl: &G, gl_version: GlVersion) {} + + fn post_destroy(&mut self, gl: &G, gl_version: GlVersion) {} +} + +pub struct TrivialCsm(); + +impl ContextStateManager for TrivialCsm {} + +/// This `ContextStateManager` is based on the upstream OpenGL example from +/// imgui, where an attempt is made to save and restore the OpenGL context state +/// before and after rendering. +/// +/// It is unlikely that any such attempt will be comprehensive for all possible +/// applications, due to the complexity of OpenGL and the possibility of +/// arbitrary extensions. However, it remains as a useful tool for quickly +/// getting started, and a good example of how to use a `ContextStateManager` to +/// customise the renderer. +#[allow(clippy::struct_excessive_bools)] +#[derive(Default)] +pub struct StateBackupCsm { + active_texture: i32, + program: i32, + texture: i32, + #[cfg(feature = "bind_sampler_support")] + sampler: Option, + array_buffer: i32, + #[cfg(feature = "polygon_mode_support")] + polygon_mode: Option<[i32; 2]>, + viewport: [i32; 4], + scissor_box: [i32; 4], + blend_src_rgb: i32, + blend_dst_rgb: i32, + blend_src_alpha: i32, + blend_dst_alpha: i32, + blend_equation_rgb: i32, + blend_equation_alpha: i32, + blend_enabled: bool, + cull_face_enabled: bool, + depth_test_enabled: bool, + stencil_test_enabled: bool, + scissor_test_enabled: bool, + #[cfg(feature = "primitive_restart_support")] + primitive_restart_enabled: Option, + #[cfg(feature = "bind_vertex_array_support")] + vertex_array_object: Option, +} + +impl ContextStateManager for StateBackupCsm { + fn pre_init(&mut self, gl: &G, _gl_version: GlVersion) -> Result<(), InitError> { + self.texture = unsafe { gl.get_parameter_i32(glow::TEXTURE_BINDING_2D) }; + Ok(()) + } + + fn post_init(&mut self, gl: &G, _gl_version: GlVersion) -> Result<(), InitError> { + #[allow(clippy::clippy::cast_sign_loss)] + unsafe { + gl.bind_texture(glow::TEXTURE_2D, Some(self.texture as _)); + } + Ok(()) + } + + fn pre_render(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), RenderError> { + #[allow(clippy::cast_sign_loss)] + unsafe { + self.active_texture = gl.get_parameter_i32(glow::ACTIVE_TEXTURE); + self.program = gl.get_parameter_i32(glow::CURRENT_PROGRAM); + self.texture = gl.get_parameter_i32(glow::TEXTURE_BINDING_2D); + #[cfg(feature = "bind_sampler_support")] + if gl_version.bind_sampler_support() { + self.sampler = Some(gl.get_parameter_i32(glow::SAMPLER_BINDING)); + } else { + self.sampler = None; + } + self.array_buffer = gl.get_parameter_i32(glow::ARRAY_BUFFER_BINDING); + + #[cfg(feature = "bind_vertex_array_support")] + if gl_version.bind_vertex_array_support() { + self.vertex_array_object = + Some(gl.get_parameter_i32(glow::VERTEX_ARRAY_BINDING) as _); + } + + #[cfg(feature = "polygon_mode_support")] + if gl_version.polygon_mode_support() { + if self.polygon_mode.is_none() { + self.polygon_mode = Some(Default::default()); + } + gl.get_parameter_i32_slice(glow::POLYGON_MODE, self.polygon_mode.as_mut().unwrap()); + } else { + self.polygon_mode = None; + } + gl.get_parameter_i32_slice(glow::VIEWPORT, &mut self.viewport); + gl.get_parameter_i32_slice(glow::SCISSOR_BOX, &mut self.scissor_box); + self.blend_src_rgb = gl.get_parameter_i32(glow::BLEND_SRC_RGB); + self.blend_dst_rgb = gl.get_parameter_i32(glow::BLEND_DST_RGB); + self.blend_src_alpha = gl.get_parameter_i32(glow::BLEND_SRC_ALPHA); + self.blend_dst_alpha = gl.get_parameter_i32(glow::BLEND_DST_ALPHA); + self.blend_equation_rgb = gl.get_parameter_i32(glow::BLEND_EQUATION_RGB); + self.blend_equation_alpha = gl.get_parameter_i32(glow::BLEND_EQUATION_ALPHA); + self.blend_enabled = gl.is_enabled(glow::BLEND); + self.cull_face_enabled = gl.is_enabled(glow::CULL_FACE); + self.depth_test_enabled = gl.is_enabled(glow::DEPTH_TEST); + self.stencil_test_enabled = gl.is_enabled(glow::STENCIL_TEST); + self.scissor_test_enabled = gl.is_enabled(glow::SCISSOR_TEST); + #[cfg(feature = "primitive_restart_support")] + if gl_version.primitive_restart_support() { + self.primitive_restart_enabled = Some(gl.is_enabled(glow::PRIMITIVE_RESTART)); + } else { + self.primitive_restart_enabled = None; + } + } + Ok(()) + } + + fn post_render(&mut self, gl: &G, _gl_version: GlVersion) -> Result<(), RenderError> { + #![allow(clippy::cast_sign_loss)] + unsafe { + gl.use_program(Some(self.program as _)); + gl.bind_texture(glow::TEXTURE_2D, Some(self.texture as _)); + #[cfg(feature = "bind_sampler_support")] + if let Some(sampler) = self.sampler { + gl.bind_sampler(0, Some(sampler as _)); + } + gl.active_texture(self.active_texture as _); + #[cfg(feature = "bind_vertex_array_support")] + if let Some(vao) = self.vertex_array_object { + gl.bind_vertex_array(Some(vao)); + } + gl.bind_buffer(glow::ARRAY_BUFFER, Some(self.array_buffer as _)); + gl.blend_equation_separate( + self.blend_equation_rgb as _, + self.blend_equation_alpha as _, + ); + gl.blend_func_separate( + self.blend_src_rgb as _, + self.blend_dst_rgb as _, + self.blend_src_alpha as _, + self.blend_dst_alpha as _, + ); + if self.blend_enabled { + gl.enable(glow::BLEND) + } else { + gl.disable(glow::BLEND); + } + if self.cull_face_enabled { + gl.enable(glow::CULL_FACE) + } else { + gl.disable(glow::CULL_FACE) + } + if self.depth_test_enabled { + gl.enable(glow::DEPTH_TEST) + } else { + gl.disable(glow::DEPTH_TEST) + } + if self.stencil_test_enabled { + gl.enable(glow::STENCIL_TEST) + } else { + gl.disable(glow::STENCIL_TEST) + } + if self.scissor_test_enabled { + gl.enable(glow::SCISSOR_TEST) + } else { + gl.disable(glow::SCISSOR_TEST) + } + #[cfg(feature = "primitive_restart_support")] + if let Some(restart_enabled) = self.primitive_restart_enabled { + if restart_enabled { + gl.enable(glow::PRIMITIVE_RESTART) + } else { + gl.disable(glow::PRIMITIVE_RESTART) + } + } + #[cfg(feature = "polygon_mode_support")] + if let Some([mode, _]) = self.polygon_mode { + gl.polygon_mode(glow::FRONT_AND_BACK, mode as _); + } + gl.viewport( + self.viewport[0], + self.viewport[1], + self.viewport[2], + self.viewport[3], + ); + gl.scissor( + self.scissor_box[0], + self.scissor_box[1], + self.scissor_box[2], + self.scissor_box[3], + ); + } + Ok(()) + } +} + +pub trait ShaderProvider { + /// Called during renderer initialization, before this call the shader + /// provide should be in a neutral state and have not interacted with the + /// OpenGL context. + /// + /// Implementors should use this opporunity to check whether the version of + /// the GL context (found with `GlVersion::read`) is compatible with the + /// shader they provide. + /// + /// # Errors + /// Any error creating the GL objects, compiling or linking or loading the + /// shaders, or an GL context with an incompatible OpenGL version will + /// result in an error. + fn initialize(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), ShaderError>; + + fn data(&self) -> &GenericShaderData; +} + +/// A generic shader provider that parses `GL_VERSION` and +/// `GL_SHADING_LANGUAGE_VERSION` at runtime in order to generate shaders which +/// should work on a wide variety of modern devices (GL >= 3.3 and GLES >= 2.0 +/// are expected to work). +pub struct AutoShaderProvider(GenericShaderData); + +impl ShaderProvider for AutoShaderProvider { + fn initialize(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), ShaderError> { + const VERTEX_BODY: &str = r#" +layout (location = 0) in vec2 position; +layout (location = 1) in vec2 uv; +layout (location = 2) in vec4 color; + +uniform mat4 matrix; +out vec2 fragment_uv; +out vec4 fragment_color; + +void main() { + fragment_uv = uv; + fragment_color = color; + gl_Position = matrix * vec4(position.xy, 0, 1); +} +"#; + const FRAGMENT_BODY: &str = r#" +in vec2 fragment_uv; +in vec4 fragment_color; + +uniform sampler2D tex; +layout (location = 0) out vec4 out_color; + +void main() { + out_color = fragment_color * texture(tex, fragment_uv.st); +} +"#; + + let glsl_version = GlslVersion::read(gl); + + // Find the lowest common denominator version + let is_gles = gl_version.is_gles || glsl_version.is_gles; + let (major, minor) = if let std::cmp::Ordering::Less = gl_version + .major + .cmp(&glsl_version.major) + .then(gl_version.minor.cmp(&glsl_version.minor)) + { + (gl_version.major, gl_version.minor) + } else { + (glsl_version.major, glsl_version.minor) + }; + + if is_gles && major < 2 { + return Err(ShaderError::IncompatibleVersion(format!( + "This auto-shader OpenGL version 3.0 or OpenGL ES version 2.0 or higher, found: ES {}.{}", + major, minor + ))); + } + if !is_gles && major < 3 { + return Err(ShaderError::IncompatibleVersion(format!( + "This auto-shader OpenGL version 3.0 or OpenGL ES version 2.0 or higher, found: {}.{}", + major, minor + ))); + } + + let vertex_source = format!( + "#version {major}{minor}{es_extras}\n{body}", + major = major, + minor = minor * 10, + es_extras = if is_gles { + " es\nprecision mediump float;" + } else { + "" + }, + body = VERTEX_BODY, + ); + let fragment_source = format!( + "#version {major}{minor}{es_extras}\n{body}", + major = major, + minor = minor * 10, + es_extras = if is_gles { + " es\nprecision mediump float;" + } else { + "" + }, + body = FRAGMENT_BODY, + ); + + create_shaders(&mut self.0, gl, &vertex_source, &fragment_source) + } + + fn data(&self) -> &GenericShaderData { + &self.0 + } +} + +impl Default for AutoShaderProvider { + fn default() -> Self { + Self( as Default>::default()) + } +} + +/// A shader provider for specific shaders for OpenGL ES (GLSL ES) version(s) +/// 3.0 +#[derive(Default)] +pub struct Es3ShaderProvider(GenericShaderData); + +impl ShaderProvider for Es3ShaderProvider { + fn initialize(&mut self, gl: &G, gl_version: GlVersion) -> Result<(), ShaderError> { + const VERTEX_SOURCE: &str = r#"#version 300 es +precision mediump float; + +layout (location = 0) in vec2 position; +layout (location = 1) in vec2 uv; +layout (location = 2) in vec4 color; + +uniform mat4 matrix; +out vec2 fragment_uv; +out vec4 fragment_color; + +void main() { + fragment_uv = uv; + fragment_color = color; + gl_Position = matrix * vec4(position.xy, 0, 1); +} +"#; + const FRAGMENT_SOURCE: &str = r#"#version 300 es +precision mediump float; + +in vec2 fragment_uv; +in vec4 fragment_color; + +uniform sampler2D tex; +layout (location = 0) out vec4 out_color; + +void main() { + out_color = fragment_color * texture(tex, fragment_uv.st); +} +"#; + + if !gl_version.is_gles { + return Err(ShaderError::IncompatibleVersion(format!( + "A version of OpenGL ES is required for this shader, found: {}.{}", + gl_version.major, gl_version.minor + ))); + } + if gl_version < GlVersion::gles(3, 0) { + return Err(ShaderError::IncompatibleVersion(format!( + "This shader requires OpenGL ES version 3.0 or higher, found: ES {}.{}", + gl_version.major, gl_version.minor + ))); + } + + create_shaders(&mut self.0, gl, VERTEX_SOURCE, FRAGMENT_SOURCE) + } + + fn data(&self) -> &GenericShaderData { + &self.0 + } +} + +pub struct GenericShaderData { + program: G::Program, + texture_uniform_location: G::UniformLocation, + matrix_uniform_location: G::UniformLocation, + position_attribute_index: u32, + uv_attribute_index: u32, + color_attribute_index: u32, +} + +impl Default for GenericShaderData { + fn default() -> Self { + Self { + program: Default::default(), + texture_uniform_location: Default::default(), + matrix_uniform_location: Default::default(), + position_attribute_index: Default::default(), + uv_attribute_index: Default::default(), + color_attribute_index: Default::default(), + } + } +} + +/// # Errors +/// Any error creating OpenGL objects, compiling, or linking the given shaders +/// results in an error. +pub fn create_shaders( + data: &mut GenericShaderData, + gl: &G, + vertex_source: &str, + fragment_source: &str, +) -> Result<(), ShaderError> { + let vertex_shader = + unsafe { gl.create_shader(glow::VERTEX_SHADER) }.map_err(ShaderError::CreateShader)?; + unsafe { + gl.shader_source(vertex_shader, vertex_source); + gl.compile_shader(vertex_shader); + if !gl.get_shader_compile_status(vertex_shader) { + return Err(ShaderError::CompileShader( + gl.get_shader_info_log(vertex_shader), + )); + } + } + + let fragment_shader = + unsafe { gl.create_shader(glow::FRAGMENT_SHADER) }.map_err(ShaderError::CreateShader)?; + unsafe { + gl.shader_source(fragment_shader, fragment_source); + gl.compile_shader(fragment_shader); + if !gl.get_shader_compile_status(fragment_shader) { + return Err(ShaderError::CompileShader( + gl.get_shader_info_log(fragment_shader), + )); + } + } + + let program = unsafe { gl.create_program() }.map_err(ShaderError::CreateProgram)?; + unsafe { + gl.attach_shader(program, vertex_shader); + gl.attach_shader(program, fragment_shader); + gl.link_program(program); + + if !gl.get_program_link_status(program) { + return Err(ShaderError::LinkProgram(gl.get_program_info_log(program))); + } + + gl.detach_shader(program, vertex_shader); + gl.detach_shader(program, fragment_shader); + gl.delete_shader(vertex_shader); + gl.delete_shader(fragment_shader); + } + + data.program = program; + unsafe { + data.texture_uniform_location = gl + .get_uniform_location(program, "tex") + .ok_or_else(|| ShaderError::UniformNotFound("tex".into()))?; + data.matrix_uniform_location = gl + .get_uniform_location(program, "matrix") + .ok_or_else(|| ShaderError::UniformNotFound("matrix".into()))?; + data.position_attribute_index = gl + .get_attrib_location(program, "position") + .ok_or_else(|| ShaderError::AttributeNotFound("position".into()))?; + data.uv_attribute_index = gl + .get_attrib_location(program, "uv") + .ok_or_else(|| ShaderError::AttributeNotFound("uv".into()))?; + data.color_attribute_index = gl + .get_attrib_location(program, "color") + .ok_or_else(|| ShaderError::AttributeNotFound("color".into()))?; + } + + Ok(()) +} + +#[derive(Debug)] +pub enum ShaderError { + IncompatibleVersion(String), + CreateShader(String), + CreateProgram(String), + CompileShader(String), + LinkProgram(String), + UniformNotFound(Cow<'static, str>), + AttributeNotFound(Cow<'static, str>), +} + +impl Error for ShaderError {} + +impl Display for ShaderError { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + match self { + Self::IncompatibleVersion(msg) => write!( + f, + "Shader not compatible with OpenGL version found in the context: {}", + msg + ), + Self::CreateShader(msg) => write!(f, "Error creating shader object: {}", msg), + Self::CreateProgram(msg) => write!(f, "Error creating program object: {}", msg), + Self::CompileShader(msg) => write!(f, "Error compiling shader: {}", msg), + Self::LinkProgram(msg) => write!(f, "Error linking shader program: {}", msg), + Self::UniformNotFound(uniform_name) => { + write!(f, "Uniform `{}` not found in shader program", uniform_name) + } + Self::AttributeNotFound(attribute_name) => { + write!( + f, + "Attribute `{}` not found in shader program", + attribute_name + ) + } + } + } +} + +#[derive(Debug)] +pub enum InitError { + Shader(ShaderError), + CreateBufferObject(String), + CreateTexture(String), + UserError(String), +} + +impl Error for InitError { + fn source(&self) -> Option<&(dyn Error + 'static)> { + match self { + Self::Shader(error) => Some(error), + _ => None, + } + } +} + +impl Display for InitError { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + match self { + Self::Shader(error) => write!(f, "Shader initialisation error: {}", error), + Self::CreateBufferObject(msg) => write!(f, "Error creating buffer object: {}", msg), + Self::CreateTexture(msg) => write!(f, "Error creating texture object: {}", msg), + Self::UserError(msg) => write!(f, "Initialization error: {}", msg), + } + } +} + +impl From for InitError { + fn from(error: ShaderError) -> Self { + Self::Shader(error) + } +} + +pub type RenderError = String; + +fn prepare_font_atlas( + gl: &G, + mut fonts: imgui::FontAtlasRefMut, +) -> Result { + #![allow(clippy::cast_possible_wrap)] + + let atlas_texture = fonts.build_rgba32_texture(); + + let gl_texture = unsafe { gl.create_texture() }.map_err(InitError::CreateTexture)?; + + unsafe { + gl.bind_texture(glow::TEXTURE_2D, Some(gl_texture)); + gl.tex_parameter_i32( + glow::TEXTURE_2D, + glow::TEXTURE_MIN_FILTER, + glow::LINEAR as _, + ); + gl.tex_parameter_i32( + glow::TEXTURE_2D, + glow::TEXTURE_MAG_FILTER, + glow::LINEAR as _, + ); + gl.tex_image_2d( + glow::TEXTURE_2D, + 0, + glow::RGBA as _, + atlas_texture.width as _, + atlas_texture.height as _, + 0, + glow::RGBA, + glow::UNSIGNED_BYTE, + Some(atlas_texture.data), + ) + } + + fonts.tex_id = TextureId::new(gl_texture as _); + + Ok(gl_texture) +} + +fn gl_debug_message(context: &G, message: impl AsRef) { + unsafe { + context.debug_message_insert( + glow::DEBUG_SOURCE_APPLICATION, + glow::DEBUG_TYPE_MARKER, + 0, + glow::DEBUG_SEVERITY_NOTIFICATION, + message, + ) + }; +} + +fn calculate_matrix(draw_data: &imgui::DrawData, clip_origin_is_lower_left: bool) -> [f32; 16] { + #![allow(clippy::deprecated_cfg_attr)] + + let left = draw_data.display_pos[0]; + let right = draw_data.display_pos[0] + draw_data.display_size[0]; + let top = draw_data.display_pos[1]; + let bottom = draw_data.display_pos[1] + draw_data.display_size[1]; + + #[cfg(feature = "clip_origin_support")] + let (top, bottom) = if clip_origin_is_lower_left { + (top, bottom) + } else { + (bottom, top) + }; + + #[cfg_attr(rustfmt, rustfmt::skip)] + { + [ + 2.0 / (right - left) , 0.0 , 0.0 , 0.0, + 0.0 , (2.0 / (top - bottom)) , 0.0 , 0.0, + 0.0 , 0.0 , -1.0, 0.0, + (right + left) / (left - right), (top + bottom) / (bottom - top), 0.0 , 1.0, + ] + } +} + +unsafe fn to_byte_slice(slice: &[T]) -> &[u8] { + std::slice::from_raw_parts(slice.as_ptr().cast(), slice.len() * size_of::()) +} + +const fn imgui_index_type_as_gl() -> u32 { + match size_of::() { + 1 => glow::UNSIGNED_BYTE, + 2 => glow::UNSIGNED_SHORT, + _ => glow::UNSIGNED_INT, + } +} diff --git a/imgui-glow-renderer/src/versions.rs b/imgui-glow-renderer/src/versions.rs new file mode 100644 index 0000000..96c50aa --- /dev/null +++ b/imgui-glow-renderer/src/versions.rs @@ -0,0 +1,181 @@ +#![allow(clippy::must_use_candidate)] + +#[derive(PartialEq, Clone, Copy)] +pub struct GlVersion { + pub major: u16, + pub minor: u16, + pub is_gles: bool, +} + +impl GlVersion { + pub const fn gl(major: u16, minor: u16) -> Self { + Self { + major, + minor, + is_gles: false, + } + } + + pub const fn gles(major: u16, minor: u16) -> Self { + Self { + major, + minor, + is_gles: true, + } + } + + pub fn read(gl: &G) -> Self { + Self::parse(&unsafe { gl.get_parameter_string(glow::VERSION) }) + } + + /// Parse the OpenGL version from the version string queried from the driver + /// via the `GL_VERSION` enum. + /// + /// Version strings are documented to be in the form + /// `.[.][ ]` + /// for full-fat OpenGL, and + /// `OpenGL ES .[.][ ]` + /// for OpenGL ES. + /// + /// Examples based on strings found in the wild: + /// ```rust + /// # use glow_renderer::GlVersion; + /// let version = GlVersion::parse("4.6.0 NVIDIA 465.27"); + /// assert!(!version.is_gles); + /// assert_eq!(version.major, 4); + /// assert_eq!(version.minor, 6); + /// let version = GlVersion::parse("OpenGL ES 3.2 NVIDIA 465.27"); + /// assert!(version.is_gles); + /// assert_eq!(version.major, 3); + /// assert_eq!(version.minor, 2); + /// ``` + pub fn parse(gl_version_string: &str) -> Self { + let (version_string, is_gles) = gl_version_string + .strip_prefix("OpenGL ES ") + .map_or_else(|| (gl_version_string, false), |version| (version, true)); + + let mut parts = version_string.split(|c: char| !c.is_numeric()); + let major = parts.next().unwrap_or("0").parse().unwrap_or(0); + let minor = parts.next().unwrap_or("0").parse().unwrap_or(0); + + Self { + major, + minor, + is_gles, + } + } + + /// Vertex array binding is provided by `glBindVertexArray`, which is + /// not present in OpenGL (ES) <3.0 + #[cfg(feature = "bind_vertex_array_support")] + pub fn bind_vertex_array_support(self) -> bool { + self.major >= 3 + } + + /// Vertex offset support is provided by `glDrawElementsBaseVertex`, which is + /// only present from OpenGL 3.2 and above. + #[cfg(feature = "vertex_offset_support")] + pub fn vertex_offset_support(self) -> bool { + !self.is_gles && self >= Self::gl(3, 2) + } + + /// Vertex arrays (e.g. `glBindVertexArray`) are supported from OpenGL 3.0 + /// and OpenGL ES 3.0 + #[cfg(feature = "vertex_array_support")] + pub fn vertex_array_support(self) -> bool { + self >= Self::gl(3, 0) || self >= Self::gles(3, 0) + } + + /// Separate binding of sampler (`glBindSampler`) is supported from OpenGL + /// 3.2 or ES 3.0 + #[cfg(feature = "bind_sampler_support")] + pub fn bind_sampler_support(self) -> bool { + self >= GlVersion::gl(3, 2) || self >= GlVersion::gles(3, 0) + } + + /// Setting the clip origin (`GL_CLIP_ORIGIN`) is suppoted from OpenGL 4.5 + #[cfg(feature = "clip_origin_support")] + pub fn clip_origin_support(self) -> bool { + self >= GlVersion::gl(4, 5) + } + + #[cfg(feature = "polygon_mode_support")] + pub fn polygon_mode_support(self) -> bool { + !self.is_gles + } + + #[cfg(feature = "primitive_restart_support")] + pub fn primitive_restart_support(self) -> bool { + self >= GlVersion::gl(3, 1) + } +} + +impl PartialOrd for GlVersion { + fn partial_cmp(&self, other: &Self) -> Option { + if self.is_gles == other.is_gles { + Some( + self.major + .cmp(&other.major) + .then(self.minor.cmp(&other.minor)), + ) + } else { + None + } + } +} + +pub struct GlslVersion { + pub major: u16, + pub minor: u16, + pub is_gles: bool, +} + +impl GlslVersion { + pub fn read(gl: &G) -> Self { + Self::parse(&unsafe { gl.get_parameter_string(glow::SHADING_LANGUAGE_VERSION) }) + } + + /// Parse the OpenGL version from the version string queried from the driver + /// via the `GL_SHADING_LANGUAGE_VERSION` enum. + /// + /// Version strings are documented to be in the form + /// `.[.][ ]` + /// for full-fat OpenGL, and + /// `OpenGL ES GLSL ES .[.][ ]` + /// for OpenGL ES (however, strings omitting that prefix have been observed). + /// + /// Examples based on strings found in the wild: + /// ```rust + /// # use glow_renderer::GlslVersion; + /// let version = GlslVersion::parse("4.60 NVIDIA"); + /// assert!(!version.is_gles); + /// assert_eq!(version.major, 4); + /// assert_eq!(version.minor, 6); + /// let version = GlslVersion::parse("OpenGL ES GLSL ES 3.20"); + /// assert!(version.is_gles); + /// assert_eq!(version.major, 3); + /// assert_eq!(version.minor, 2); + /// ``` + pub fn parse(gl_shading_language_version: &str) -> Self { + let (version_string, is_gles) = gl_shading_language_version + .strip_prefix("OpenGL ES GLSL ES ") + .map_or_else( + || (gl_shading_language_version, false), + |version| (version, true), + ); + + let mut parts = version_string.split(|c: char| !c.is_numeric()); + let major = parts.next().unwrap_or("0").parse().unwrap_or(0); + let minor = parts.next().unwrap_or("0").parse().unwrap_or(0); + + // The minor version has been observed specified as both a single- or + // double-digit version + let minor = if minor >= 10 { minor / 10 } else { minor }; + + Self { + major, + minor, + is_gles, + } + } +}