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Diffstat (limited to 'glow/src/triangle.rs')
| -rw-r--r-- | glow/src/triangle.rs | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/glow/src/triangle.rs b/glow/src/triangle.rs new file mode 100644 index 00000000..ee7faf83 --- /dev/null +++ b/glow/src/triangle.rs @@ -0,0 +1,292 @@ +//! Draw meshes of triangles. +use crate::program; +use crate::Transformation; +use glow::HasContext; +use iced_graphics::layer; +use std::marker::PhantomData; + +pub use iced_graphics::triangle::{Mesh2D, Vertex2D}; + +const VERTEX_BUFFER_SIZE: usize = 10_000; +const INDEX_BUFFER_SIZE: usize = 10_000; + +#[derive(Debug)] +pub(crate) struct Pipeline { + program: <glow::Context as HasContext>::Program, + vertex_array: <glow::Context as HasContext>::VertexArray, + vertices: Buffer<Vertex2D>, + indices: Buffer<u32>, + transform_location: <glow::Context as HasContext>::UniformLocation, + current_transform: Transformation, +} + +impl Pipeline { + pub fn new(gl: &glow::Context) -> Pipeline { + let program = unsafe { + program::create( + gl, + &[ + (glow::VERTEX_SHADER, include_str!("shader/triangle.vert")), + ( + glow::FRAGMENT_SHADER, + include_str!("shader/triangle.frag"), + ), + ], + ) + }; + + let transform_location = + unsafe { gl.get_uniform_location(program, "u_Transform") } + .expect("Get transform location"); + + unsafe { + gl.use_program(Some(program)); + + let transform: [f32; 16] = Transformation::identity().into(); + gl.uniform_matrix_4_f32_slice( + Some(transform_location), + false, + &transform, + ); + + gl.use_program(None); + } + + let vertex_array = + unsafe { gl.create_vertex_array().expect("Create vertex array") }; + + unsafe { + gl.bind_vertex_array(Some(vertex_array)); + } + + let vertices = unsafe { + Buffer::new( + gl, + glow::ARRAY_BUFFER, + glow::DYNAMIC_DRAW, + VERTEX_BUFFER_SIZE, + ) + }; + + let indices = unsafe { + Buffer::new( + gl, + glow::ELEMENT_ARRAY_BUFFER, + glow::DYNAMIC_DRAW, + INDEX_BUFFER_SIZE, + ) + }; + + unsafe { + let stride = std::mem::size_of::<Vertex2D>() as i32; + + gl.enable_vertex_attrib_array(0); + gl.vertex_attrib_pointer_f32(0, 2, glow::FLOAT, false, stride, 0); + + gl.enable_vertex_attrib_array(1); + gl.vertex_attrib_pointer_f32( + 1, + 4, + glow::FLOAT, + false, + stride, + 4 * 2, + ); + + gl.bind_vertex_array(None); + } + + Pipeline { + program, + vertex_array, + vertices, + indices, + transform_location, + current_transform: Transformation::identity(), + } + } + + pub fn draw( + &mut self, + gl: &glow::Context, + target_height: u32, + transformation: Transformation, + scale_factor: f32, + meshes: &[layer::Mesh<'_>], + ) { + unsafe { + gl.enable(glow::MULTISAMPLE); + gl.enable(glow::SCISSOR_TEST); + gl.use_program(Some(self.program)); + gl.bind_vertex_array(Some(self.vertex_array)); + } + + // This looks a bit crazy, but we are just counting how many vertices + // and indices we will need to handle. + // TODO: Improve readability + let (total_vertices, total_indices) = meshes + .iter() + .map(|layer::Mesh { buffers, .. }| { + (buffers.vertices.len(), buffers.indices.len()) + }) + .fold((0, 0), |(total_v, total_i), (v, i)| { + (total_v + v, total_i + i) + }); + + // Then we ensure the current buffers are big enough, resizing if + // necessary + unsafe { + self.vertices.bind(gl, total_vertices); + self.indices.bind(gl, total_indices); + } + + // We upload all the vertices and indices upfront + let mut last_vertex = 0; + let mut last_index = 0; + + for layer::Mesh { buffers, .. } in meshes { + unsafe { + gl.buffer_sub_data_u8_slice( + glow::ARRAY_BUFFER, + (last_vertex * std::mem::size_of::<Vertex2D>()) as i32, + bytemuck::cast_slice(&buffers.vertices), + ); + + gl.buffer_sub_data_u8_slice( + glow::ELEMENT_ARRAY_BUFFER, + (last_index * std::mem::size_of::<u32>()) as i32, + bytemuck::cast_slice(&buffers.indices), + ); + + last_vertex += buffers.vertices.len(); + last_index += buffers.indices.len(); + } + } + + // Then we draw each mesh using offsets + let mut last_vertex = 0; + let mut last_index = 0; + + for layer::Mesh { + buffers, + origin, + clip_bounds, + } in meshes + { + let transform = + transformation * Transformation::translate(origin.x, origin.y); + + let clip_bounds = (*clip_bounds * scale_factor).round(); + + unsafe { + if self.current_transform != transform { + let matrix: [f32; 16] = transform.into(); + gl.uniform_matrix_4_f32_slice( + Some(self.transform_location), + false, + &matrix, + ); + + self.current_transform = transform; + } + + gl.scissor( + clip_bounds.x as i32, + (target_height - (clip_bounds.y + clip_bounds.height)) + as i32, + clip_bounds.width as i32, + clip_bounds.height as i32, + ); + + gl.draw_elements_base_vertex( + glow::TRIANGLES, + buffers.indices.len() as i32, + glow::UNSIGNED_INT, + (last_index * std::mem::size_of::<u32>()) as i32, + last_vertex as i32, + ); + + last_vertex += buffers.vertices.len(); + last_index += buffers.indices.len(); + } + } + + unsafe { + gl.bind_vertex_array(None); + gl.use_program(None); + gl.disable(glow::SCISSOR_TEST); + gl.disable(glow::MULTISAMPLE); + } + } +} + +#[repr(C)] +#[derive(Debug, Clone, Copy)] +struct Uniforms { + transform: [f32; 16], +} + +unsafe impl bytemuck::Zeroable for Uniforms {} +unsafe impl bytemuck::Pod for Uniforms {} + +impl Default for Uniforms { + fn default() -> Self { + Self { + transform: *Transformation::identity().as_ref(), + } + } +} + +impl From<Transformation> for Uniforms { + fn from(transformation: Transformation) -> Uniforms { + Self { + transform: transformation.into(), + } + } +} + +#[derive(Debug)] +struct Buffer<T> { + raw: <glow::Context as HasContext>::Buffer, + target: u32, + usage: u32, + size: usize, + phantom: PhantomData<T>, +} + +impl<T> Buffer<T> { + pub unsafe fn new( + gl: &glow::Context, + target: u32, + usage: u32, + size: usize, + ) -> Self { + let raw = gl.create_buffer().expect("Create buffer"); + + let mut buffer = Buffer { + raw, + target, + usage, + size: 0, + phantom: PhantomData, + }; + + buffer.bind(gl, size); + + buffer + } + + pub unsafe fn bind(&mut self, gl: &glow::Context, size: usize) { + gl.bind_buffer(self.target, Some(self.raw)); + + if self.size < size { + gl.buffer_data_size( + self.target, + (size * std::mem::size_of::<T>()) as i32, + self.usage, + ); + + self.size = size; + } + } +} |