rustwasm · alexcrichton · Sep 19, 2018 · Sep 16, 2018
diff --git a/Cargo.toml b/Cargo.toml
@@ -78,6 +78,7 @@ members = [
   "examples/smorgasboard",
   "examples/wasm-in-wasm",
   "examples/webaudio",
+  "examples/webgl",
   "tests/no-std",
 ]
 

diff --git a/examples/webgl/.gitignore b/examples/webgl/.gitignore
@@ -0,0 +1,4 @@
+package-lock.json
+wasm_bindgen_webgl_demo.js
+wasm_bindgen_webgl_demo_bg.js
+wasm_bindgen_webgl_demo_bg.wasm
diff --git a/examples/webgl/Cargo.toml b/examples/webgl/Cargo.toml
@@ -0,0 +1,24 @@
+[package]
+name = "wasm-bindgen-webgl-demo"
+version = "0.1.0"
+authors = ["The wasm-bindgen Developers"]
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+js-sys = { path = "../../crates/js-sys" }
+wasm-bindgen = { path = "../.." }
+
+[dependencies.web-sys]
+path = "../../crates/web-sys"
+features = [
+  'Document',
+  'Element',
+  'HtmlCanvasElement',
+  'WebGlBuffer',
+  'WebGlRenderingContext',
+  'WebGlProgram',
+  'WebGlShader',
+  'Window',
+]
diff --git a/examples/webgl/README.md b/examples/webgl/README.md
@@ -0,0 +1,15 @@
+# WebGL Example
+
+This directory is an example of using the `web-sys` crate to interact with
+a WebGL context.
+
+You can build and run the example with:
+
+```
+$ ./build.sh
+```
+
+(or running the commands on Windows manually)
+
+and then opening up `http://localhost:8080/` in a web browser should show a
+nice triangle.
diff --git a/examples/webgl/build.sh b/examples/webgl/build.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# For more coments about what's going on here, see the `hello_world` example
+
+set -ex
+cd "$(dirname $0)"
+
+cargo +nightly build --target wasm32-unknown-unknown
+
+cargo +nightly run --manifest-path ../../crates/cli/Cargo.toml \
+  --bin wasm-bindgen -- \
+  ../../target/wasm32-unknown-unknown/debug/wasm_bindgen_webgl_demo.wasm --out-dir .
+
+npm install
+npm run serve
diff --git a/examples/webgl/index.html b/examples/webgl/index.html
@@ -0,0 +1,9 @@
+<html>
+  <head>
+    <meta content="text/html;charset=utf-8" http-equiv="Content-Type"/>
+  </head>
+  <body>
+    <canvas id="canvas" height="150" width="150" />
+    <script src='./index.js'></script>
+  </body>
+</html>
diff --git a/examples/webgl/index.js b/examples/webgl/index.js
@@ -0,0 +1,5 @@
+// For more comments about what's going on here, check out the `hello_world`
+// example.
+import('./wasm_bindgen_webgl_demo').then(webgl => {
+  webgl.draw();
+});
diff --git a/examples/webgl/package.json b/examples/webgl/package.json
@@ -0,0 +1,11 @@
+{
+  "scripts": {
+    "serve": "webpack-dev-server"
+  },
+  "devDependencies": {
+    "html-webpack-plugin": "^3.2.0",
+    "webpack": "^4.11.1",
+    "webpack-cli": "^2.0.10",
+    "webpack-dev-server": "^3.1.0"
+  }
+}
diff --git a/examples/webgl/src/lib.rs b/examples/webgl/src/lib.rs
@@ -0,0 +1,121 @@
+extern crate js_sys;
+extern crate wasm_bindgen;
+extern crate web_sys;
+
+use wasm_bindgen::prelude::*;
+use wasm_bindgen::JsCast;
+use web_sys::{WebGlProgram, WebGlRenderingContext, WebGlShader};
+
+#[wasm_bindgen]
+pub fn draw() {
+    let document = web_sys::Window::document().unwrap();
+    let canvas = document.get_element_by_id("canvas").unwrap();
+    let canvas: web_sys::HtmlCanvasElement = canvas
+        .dyn_into::<web_sys::HtmlCanvasElement>()
+        .map_err(|_| ())
+        .unwrap();
+
+    let context = canvas
+        .get_context("webgl")
+        .unwrap()
+        .unwrap()
+        .dyn_into::<WebGlRenderingContext>()
+        .unwrap();
+
+    let vert_shader = compile_shader(
+        &context,
+        WebGlRenderingContext::VERTEX_SHADER,
+        r#"
+        attribute vec4 position;
+        void main() {
+            gl_Position = position;
+        }
+    "#,
+    ).unwrap();
+    let frag_shader = compile_shader(
+        &context,
+        WebGlRenderingContext::FRAGMENT_SHADER,
+        r#"
+        void main() {
+            gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
+        }
+    "#,
+    ).unwrap();
+    let program = link_program(&context, [vert_shader, frag_shader].iter()).unwrap();
+    context.use_program(Some(&program));
+
+    let vertices = [-0.7, -0.7, 0.0, 0.7, -0.7, 0.0, 0.0, 0.7, 0.0];
+    let vert_array = js_sys::Float32Array::new(&wasm_bindgen::JsValue::from(vertices.len() as u32));
+    for (i, f) in vertices.iter().enumerate() {
+        vert_array.fill(*f, i as u32, (i + 1) as u32);
+    }
+
+    let buffer = context.create_buffer().unwrap();
+    context.bind_buffer(WebGlRenderingContext::ARRAY_BUFFER, Some(&buffer));
+    context.buffer_data_with_opt_array_buffer(
+        WebGlRenderingContext::ARRAY_BUFFER,
+        Some(&vert_array.buffer()),
+        WebGlRenderingContext::STATIC_DRAW,
+    );
+    context.vertex_attrib_pointer_with_i32(0,
+            3,
+            WebGlRenderingContext::FLOAT,
+            false,
+            0,
+            0);
+    context.enable_vertex_attrib_array(0);
+
+    context.clear_color(0.0, 0.0, 0.0, 1.0);
+    context.clear(WebGlRenderingContext::COLOR_BUFFER_BIT);
+
+    context.draw_arrays(WebGlRenderingContext::TRIANGLES, 0, (vertices.len() / 3) as i32);
+}
+
+pub 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(|| "Unknown error creating shader".into()))
+    }
+}
+
+pub fn link_program<'a, T: IntoIterator<Item = &'a WebGlShader>>(
+    context: &WebGlRenderingContext,
+    shaders: T,
+) -> Result<WebGlProgram, String> {
+    let program = context
+        .create_program()
+        .ok_or_else(|| String::from("Unable to create shader object"))?;
+    for shader in shaders {
+        context.attach_shader(&program, 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(|| "Unknown error creating program object".into()))
+    }
+}
diff --git a/examples/webgl/webpack.config.js b/examples/webgl/webpack.config.js
@@ -0,0 +1,16 @@
+const path = require('path');
+const HtmlWebpackPlugin = require('html-webpack-plugin');
+
+module.exports = {
+    entry: './index.js',
+    output: {
+        path: path.resolve(__dirname, 'dist'),
+        filename: 'index.js',
+    },
+    plugins: [
+        new HtmlWebpackPlugin({
+            template: "index.html"
+        })
+    ],
+    mode: 'development'
+};
diff --git a/guide/src/SUMMARY.md b/guide/src/SUMMARY.md
@@ -61,6 +61,7 @@
     - [The `fetch` API](./web-sys/examples/fetch.md)
     - [2D Canvas](./web-sys/examples/2d-canvas.md)
     - [WebAudio](./web-sys/examples/web-audio.md)
+    - [WebGL](./web-sys/examples/webgl.md)
     - [A Simple Paint Program](./web-sys/examples/paint.md)
 
 --------------------------------------------------------------------------------

diff --git a/guide/src/web-sys/examples/webgl.md b/guide/src/web-sys/examples/webgl.md
@@ -0,0 +1,25 @@
+# 2D Canvas
+
+This example draws a triangle to the screen using the WebGL API.
+
+[See the full source at
+`wasm-bindgen/examples/webgl`.](https://github.com/rustwasm/wasm-bindgen/tree/master/examples/webgl)
+
+## `Cargo.toml`
+
+The `Cargo.toml` enables features necessary to obtain and use a WebGL
+rendering context.
+
+```toml
+{{#include ../../../../examples/webgl/Cargo.toml}}
+```
+
+## `src/lib.rs`
+
+This source file handles all of the necessary logic to obtain a rendering
+context, compile shaders, fill a buffer with vertex coordinates, and draw a
+triangle to the screen.
+
+```rust
+{{#include ../../../../examples/webgl/src/lib.rs}}
+```