From 42b6de79513ec63109ddd3cb9acab4811eacfc58 Mon Sep 17 00:00:00 2001
From: mmulli <6304106+mmulli@users.noreply.github.com>
Date: Sat, 3 Jul 2021 17:21:21 +1000
Subject: [PATCH] Upgraded examples/webgl to use WebGL2 instead of WebGL1

---
 examples/webgl/Cargo.toml |  3 +-
 examples/webgl/src/lib.rs | 78 ++++++++++++++++++++++++---------------
 2 files changed, 50 insertions(+), 31 deletions(-)

diff --git a/examples/webgl/Cargo.toml b/examples/webgl/Cargo.toml
index efd8432b6cf..6e489ce8f5b 100644
--- a/examples/webgl/Cargo.toml
+++ b/examples/webgl/Cargo.toml
@@ -18,7 +18,8 @@ features = [
   'Element',
   'HtmlCanvasElement',
   'WebGlBuffer',
-  'WebGlRenderingContext',
+  'WebGlVertexArrayObject',
+  'WebGl2RenderingContext',
   'WebGlProgram',
   'WebGlShader',
   'Window',
diff --git a/examples/webgl/src/lib.rs b/examples/webgl/src/lib.rs
index 37acafa3837..34c7a4f6a13 100644
--- a/examples/webgl/src/lib.rs
+++ b/examples/webgl/src/lib.rs
@@ -1,6 +1,6 @@
 use wasm_bindgen::prelude::*;
 use wasm_bindgen::JsCast;
-use web_sys::{WebGlProgram, WebGlRenderingContext, WebGlShader};
+use web_sys::{WebGl2RenderingContext, WebGlProgram, WebGlShader};
 
 #[wasm_bindgen(start)]
 pub fn start() -> Result<(), JsValue> {
@@ -9,36 +9,45 @@ pub fn start() -> Result<(), JsValue> {
     let canvas: web_sys::HtmlCanvasElement = canvas.dyn_into::<web_sys::HtmlCanvasElement>()?;
 
     let context = canvas
-        .get_context("webgl")?
+        .get_context("webgl2")?
         .unwrap()
-        .dyn_into::<WebGlRenderingContext>()?;
+        .dyn_into::<WebGl2RenderingContext>()?;
 
     let vert_shader = compile_shader(
         &context,
-        WebGlRenderingContext::VERTEX_SHADER,
-        r#"
-        attribute vec4 position;
+        WebGl2RenderingContext::VERTEX_SHADER,
+        r##"#version 300 es
+ 
+        in vec4 position;
+
         void main() {
+        
             gl_Position = position;
         }
-    "#,
+        "##,
     )?;
+
     let frag_shader = compile_shader(
         &context,
-        WebGlRenderingContext::FRAGMENT_SHADER,
-        r#"
+        WebGl2RenderingContext::FRAGMENT_SHADER,
+        r##"#version 300 es
+    
+        precision highp float;
+        out vec4 outColor;
+        
         void main() {
-            gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
+            outColor = vec4(1, 1, 1, 1);
         }
-    "#,
+        "##,
     )?;
     let program = link_program(&context, &vert_shader, &frag_shader)?;
     context.use_program(Some(&program));
 
     let vertices: [f32; 9] = [-0.7, -0.7, 0.0, 0.7, -0.7, 0.0, 0.0, 0.7, 0.0];
 
-    let buffer = context.create_buffer().ok_or("failed to create buffer")?;
-    context.bind_buffer(WebGlRenderingContext::ARRAY_BUFFER, Some(&buffer));
+    let position_attribute_location = context.get_attrib_location(&program, "position");
+    let buffer = context.create_buffer().ok_or("Failed to create buffer")?;
+    context.bind_buffer(WebGl2RenderingContext::ARRAY_BUFFER, Some(&buffer));
 
     // Note that `Float32Array::view` is somewhat dangerous (hence the
     // `unsafe`!). This is creating a raw view into our module's
@@ -49,31 +58,40 @@ pub fn start() -> Result<(), JsValue> {
     // As a result, after `Float32Array::view` we have to be very careful not to
     // do any memory allocations before it's dropped.
     unsafe {
-        let vert_array = js_sys::Float32Array::view(&vertices);
+        let positions_array_buf_view = js_sys::Float32Array::view(&vertices);
 
         context.buffer_data_with_array_buffer_view(
-            WebGlRenderingContext::ARRAY_BUFFER,
-            &vert_array,
-            WebGlRenderingContext::STATIC_DRAW,
+            WebGl2RenderingContext::ARRAY_BUFFER,
+            &positions_array_buf_view,
+            WebGl2RenderingContext::STATIC_DRAW,
         );
     }
 
-    context.vertex_attrib_pointer_with_i32(0, 3, WebGlRenderingContext::FLOAT, false, 0, 0);
-    context.enable_vertex_attrib_array(0);
+    let vao = context
+        .create_vertex_array()
+        .ok_or("Could not create vertex array object")?;
+    context.bind_vertex_array(Some(&vao));
 
-    context.clear_color(0.0, 0.0, 0.0, 1.0);
-    context.clear(WebGlRenderingContext::COLOR_BUFFER_BIT);
+    context.vertex_attrib_pointer_with_i32(0, 3, WebGl2RenderingContext::FLOAT, false, 0, 0);
+    context.enable_vertex_attrib_array(position_attribute_location as u32);
+
+    context.bind_vertex_array(Some(&vao));
+
+    let vert_count = (vertices.len() / 3) as i32;
+    draw(&context, vert_count);
 
-    context.draw_arrays(
-        WebGlRenderingContext::TRIANGLES,
-        0,
-        (vertices.len() / 3) as i32,
-    );
     Ok(())
 }
 
+fn draw(context: &WebGl2RenderingContext, vert_count: i32) {
+    context.clear_color(0.0, 0.0, 0.0, 1.0);
+    context.clear(WebGl2RenderingContext::COLOR_BUFFER_BIT);
+
+    context.draw_arrays(WebGl2RenderingContext::TRIANGLES, 0, vert_count);
+}
+
 pub fn compile_shader(
-    context: &WebGlRenderingContext,
+    context: &WebGl2RenderingContext,
     shader_type: u32,
     source: &str,
 ) -> Result<WebGlShader, String> {
@@ -84,7 +102,7 @@ pub fn compile_shader(
     context.compile_shader(&shader);
 
     if context
-        .get_shader_parameter(&shader, WebGlRenderingContext::COMPILE_STATUS)
+        .get_shader_parameter(&shader, WebGl2RenderingContext::COMPILE_STATUS)
         .as_bool()
         .unwrap_or(false)
     {
@@ -97,7 +115,7 @@ pub fn compile_shader(
 }
 
 pub fn link_program(
-    context: &WebGlRenderingContext,
+    context: &WebGl2RenderingContext,
     vert_shader: &WebGlShader,
     frag_shader: &WebGlShader,
 ) -> Result<WebGlProgram, String> {
@@ -110,7 +128,7 @@ pub fn link_program(
     context.link_program(&program);
 
     if context
-        .get_program_parameter(&program, WebGlRenderingContext::LINK_STATUS)
+        .get_program_parameter(&program, WebGl2RenderingContext::LINK_STATUS)
         .as_bool()
         .unwrap_or(false)
     {