docs(webgl): Explain why white background is required for comparison

Native OpenGL screenshots have transparent backgrounds (alpha=0 in undrawn
areas). The comparison script flattens both images to white before comparing.
WebGL must use white clear color to match this behavior.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Viktor Vaczi 2026-01-08 12:35:49 +01:00
commit 10e9cd96f6

View file

@ -176,7 +176,8 @@ bool GALTestApp::OnInit() {
// We need to match this: GAL thinks it's 800x600, but actually renders to 1600x1200
g_gal->SetScreenSize(VECTOR2I(CANVAS_WIDTH, CANVAS_HEIGHT)); // Physical: 1600x1200
g_gal->ResizeScreen(CANVAS_WIDTH, CANVAS_HEIGHT); // Framebuffer: 1600x1200
// Use white background to match native baseline screenshots
// Native screenshots have transparent backgrounds that flatten to WHITE during comparison
// WebGL must use white background to match after flattening
g_gal->SetClearColor(KIGFX::COLOR4D(1.0, 1.0, 1.0, 1.0));
// CRITICAL: Set worldUnitLength to match native (which uses DPI=91)