bgiApplyCanvasScreenShader

Applies a post-process screen shader to a specific canvas. Searches g_canvasMap for canvasID. If found, sets canvas.activeScreenShader = shaderID. If canvas not found, function silently does nothing. No return value.

This function enables per-canvas post-processing effects. ShaderID is from b3dLoadScreenShader. Canvas.activeScreenShader is stored in DX12Canvas structure. Shader is applied during bgiFlipCanvas - BBR_Shaders3D_ApplyCanvasScreenShader renders fullscreen quad with shader. Screen shaders operate on completed render target (after all 3D geometry and 2D overlay). Common effects: bloom, color grading, CRT scanlines, depth of field, motion blur, vignette. Each canvas can have different shader - enables different visual styles per viewport. ShaderID 0 means no shader (default). Shader persists until changed via bgiApplyCanvasScreenShader or cleared via bgiClearCanvasScreenShader. Applied BEFORE swap chain Present in bgiFlipCanvas. Shader reads from offscreen render target, writes to canvas back buffer. Use for preview modes, artistic effects, debugging visualizations. Silent failure if canvas doesn't exist - check return value of bgiCreateCanvas3D. Common pattern: apply shader at initialization or when user toggles effect.