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use js_sys::WebAssembly; use wasm_bindgen::prelude::*; use wasm_bindgen::JsCast; use web_sys::{WebGlProgram, WebGlRenderingContext, WebGlShader}; use std::collections::HashMap; pub struct RenderItem { vertices: Vec<f32>, shader_name: String, uniforms: Option<HashMap<String, (f32, f32, f32, f32)>>, } impl RenderItem { pub fn new( vertices: Vec<f32>, shader_name: String, uniforms: Option<HashMap<String, (f32, f32, f32, f32)>>, ) -> RenderItem { RenderItem { vertices, shader_name, uniforms, } } } impl RenderItem { pub fn set_uniform(&mut self, name: String, value: (f32, f32, f32, f32)) { if let Some(uniforms) = self.uniforms.as_mut() { uniforms.insert(name, value); } } } pub struct Renderer { context: WebGlRenderingContext, shaders: HashMap<String, WebGlProgram>, } impl Renderer { pub fn new() -> Result<Renderer, JsValue> { let document = web_sys::window().unwrap().document().unwrap(); let canvas = document.get_element_by_id("canvas").unwrap(); let canvas: web_sys::HtmlCanvasElement = canvas.dyn_into::<web_sys::HtmlCanvasElement>()?; let context = canvas .get_context("webgl")? .unwrap() .dyn_into::<WebGlRenderingContext>()?; let shaders = HashMap::<String, WebGlProgram>::new(); let mut renderer = Renderer { context, shaders }; renderer.add_shader( "default".into(), " attribute vec4 position; void main() { gl_Position = position; } " .into(), " void main() { gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0); } " .into(), )?; Ok(renderer) } pub fn draw(self, render_items: Vec<RenderItem>) -> Result<(), JsValue> { self.context.clear_color(0.0, 0.0, 0.0, 1.0); for render_item in render_items { let shader_name = render_item.shader_name; let program = self.shaders.get(shader_name.as_str()).unwrap(); self.context.use_program(Some(&program)); if let Some(uni) = render_item.uniforms { for (key, value) in uni.iter() { let location = self.context.get_uniform_location(program, key.as_str()); self.context .uniform4f(location.as_ref(), value.0, value.1, value.2, value.3); } } let vertices = render_item.vertices; let memory_buffer = wasm_bindgen::memory() .dyn_into::<WebAssembly::Memory>()? .buffer(); let vertices_location = vertices.as_ptr() as u32 / 4; let vert_array = js_sys::Float32Array::new(&memory_buffer) .subarray(vertices_location, vertices_location + vertices.len() as u32); let buffer = self .context .create_buffer() .ok_or("failed to create buffer")?; self.context .bind_buffer(WebGlRenderingContext::ARRAY_BUFFER, Some(&buffer)); self.context.buffer_data_with_array_buffer_view( WebGlRenderingContext::ARRAY_BUFFER, &vert_array, WebGlRenderingContext::STATIC_DRAW, ); self.context.vertex_attrib_pointer_with_i32( 0, 3, WebGlRenderingContext::FLOAT, false, 0, 0, ); self.context.enable_vertex_attrib_array(0); self.context.clear(WebGlRenderingContext::COLOR_BUFFER_BIT); self.context.draw_arrays( WebGlRenderingContext::TRIANGLES, 0, (vertices.len() / 3) as i32, ); } Ok(()) } pub fn add_shader( &mut self, name: String, vertex_shader: String, fragment_shader: String, ) -> Result<(), String> { let vert_shader = Self::compile_shader( &self.context, WebGlRenderingContext::VERTEX_SHADER, vertex_shader.as_str(), )?; let frag_shader = Self::compile_shader( &self.context, WebGlRenderingContext::FRAGMENT_SHADER, fragment_shader.as_str(), )?; let program = Self::link_program(&self.context, &vert_shader, &frag_shader)?; self.shaders.insert(name.into(), program); Ok(()) } fn compile_shader( context: &WebGlRenderingContext, shader_type: u32, source: &str, ) -> Result<WebGlShader, String> { let shader = context .create_shader(shader_type) .ok_or_else(|| String::from("Unable to create shader object"))?; context.shader_source(&shader, source); context.compile_shader(&shader); if context .get_shader_parameter(&shader, WebGlRenderingContext::COMPILE_STATUS) .as_bool() .unwrap_or(false) { Ok(shader) } else { Err(context .get_shader_info_log(&shader) .unwrap_or_else(|| String::from("Unknown error creating shader"))) } } fn link_program( context: &WebGlRenderingContext, vert_shader: &WebGlShader, frag_shader: &WebGlShader, ) -> Result<WebGlProgram, String> { let program = context .create_program() .ok_or_else(|| String::from("Unable to create shader object"))?; context.attach_shader(&program, vert_shader); context.attach_shader(&program, frag_shader); context.link_program(&program); if context .get_program_parameter(&program, WebGlRenderingContext::LINK_STATUS) .as_bool() .unwrap_or(false) { Ok(program) } else { Err(context .get_program_info_log(&program) .unwrap_or_else(|| String::from("Unknown error creating program object"))) } } }