Root cause: used OpenGL cubemap conventions (up=+Y) instead of Vulkan (up=-Y)
for X and Z faces. Also applied M22 *= -1 flip to shadow projection which
is wrong — that flip is only for swapchain rendering, not for offscreen
cubemap rendering.
Fix:
- Faces 0,1,4,5 (+X,-X,+Z,-Z): up = (0,-1,0) — Vulkan cubemap convention
- Face 2 (+Y): up = (0,0,1) — was (0,0,-1), now correct
- Face 3 (-Y): up = (0,0,-1) — was (0,0,1), now correct
- Removed M22 *= -1 from shadow projection (not needed for offscreen cube)
- 227 tests, all pass
Root cause of broken shadows: depth buffer stores non-linear NDC depth,
not linear distance. closestDepth * 60.0 was wrong conversion.
Fix: switch from depth-only to R32_SFLOAT color attachment approach:
- Shadow vertex shader outputs world position to fragment
- Shadow fragment shader writes length(fragPos - lightPos) / farPlane
- Main fragment shader samples cubemap, multiplies by FAR_PLANE=60
- Separate color cube (R32_SFLOAT, sampled) + depth cube (D32_SFLOAT, depth test)
- Shadow pipeline: 1 color attachment (R) + depth attachment
- Color clear = 1.0 (max distance), depth clear = 1.0
Tests: 227 total, all pass
- ShadowMapFaceDirectionTests: 6 face directions, 90° FOV, up vectors,
valid matrices, far plane consistency
- ShadowShaderTests: all 6 SPIR-V shaders exist
emil28092005