Phase 4 Step 6: Canvas WebGL context

[thomasnemer]

Parent: #41

Goal

Implement the Canvas WebGL context (WebGLRenderingContext) so that JavaScript can use GPU-accelerated 3D graphics on <canvas> elements.

Prerequisites

• Step 5 (Canvas 2D context — reuse canvas element infrastructure)

Implementation

• Expose WebGLRenderingContext (WebGL 1.0) in Boa JS engine
• Map WebGL API calls to wgpu equivalents
• GLSL ES to WGSL shader translation via naga (already a transitive dep of wgpu)
• Shader management: createShader, shaderSource, compileShader, createProgram, linkProgram
• Buffer management: createBuffer, bindBuffer, bufferData
• Texture management: createTexture, bindTexture, texImage2D
• Framebuffer management: createFramebuffer, bindFramebuffer, framebufferTexture2D
• Draw calls: drawArrays, drawElements
• Uniforms and attributes: getUniformLocation, uniformNf/i, vertexAttribPointer, enableVertexAttribArray
• Render to same offscreen texture as 2D context
• WebGL 2.0 deferred to Phase 5+

Tests

• Shader compilation and linking tests (GLSL ES → WGSL)
• Buffer creation and data upload tests
• Texture creation and sampling tests
• Draw call output validation tests
• Context switching between 2D and WebGL on same canvas

Acceptance Criteria

• WebGL 1.0 API is functional in JS
• GLSL ES shaders translate to WGSL and compile correctly
• Basic WebGL programs (triangle, textured quad) render correctly
• WebGL canvas displays in the page using shared offscreen texture