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fix: stabilize CSM shadows
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@hoffstadt
hoffstadt committed Jan 7, 2025
1 parent 7ea39b3 commit 728d653
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Showing 3 changed files with 66 additions and 52 deletions.
1 change: 1 addition & 0 deletions extensions/pl_renderer_ext.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2467,6 +2467,7 @@ pl_refr_reload_scene_shaders(uint32_t uSceneHandle)
.pTempConstantData = aiConstantData0,
.tGraphicsState = {
.ulDepthWriteEnabled = 1,
.ulDepthClampEnabled = 1,
.ulDepthMode = PL_COMPARE_MODE_GREATER_OR_EQUAL,
.ulCullMode = PL_CULL_MODE_NONE,
.ulWireframe = 0,
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115 changes: 64 additions & 51 deletions extensions/pl_renderer_internal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1464,6 +1464,8 @@ pl_refr_generate_cascaded_shadow_map(plRenderEncoder* ptEncoder, plCommandBuffer
const uint32_t uFrameIdx = gptGfx->get_current_frame_index();

plCameraComponent* ptSceneCamera = gptECS->get_component(&ptScene->tComponentLibrary, PL_COMPONENT_TYPE_CAMERA, tCamera);
const float g = 1.0f / tanf(ptSceneCamera->fFieldOfView / 2.0f);
const float s = ptSceneCamera->fAspectRatio;

// common calculations
const float fFarClip = ptSceneCamera->fFarZ;
Expand All @@ -1479,9 +1481,6 @@ pl_refr_generate_cascaded_shadow_map(plRenderEncoder* ptEncoder, plCommandBuffer
const plLightComponent* sbtLights = ptScene->tComponentLibrary.tLightComponentManager.pComponents;
const uint32_t uLightCount = pl_sb_size(ptScene->sbtShadowRects);

// count rects
// uint32_t uShadowCastingLightIndex = 0;

int iLastIndex = -1;
int iCurrentView = -1;
uint32_t uDCameraBufferOffset = 0;
Expand Down Expand Up @@ -1515,78 +1514,91 @@ pl_refr_generate_cascaded_shadow_map(plRenderEncoder* ptEncoder, plCommandBuffer
ptShadowData->fYOffset = (float)ptRect->iY / (float)ptScene->uShadowAtlasResolution;

plMat4 atCamViewProjs[PL_MAX_SHADOW_CASCADES] = {0};
float fLastSplitDist = 0.0;
float afLambdaCascadeSplits[PL_MAX_SHADOW_CASCADES] = {0};
float fLastSplitDist = 0.0f;
const plVec3 tDirection = pl_norm_vec3(ptLight->tDirection);
for(uint32_t uCascade = 0; uCascade < ptLight->uCascadeCount; uCascade++)
{
float fSplitDist = ptLight->afCascadeSplits[uCascade] / fClipRange;
float fSplitDist = ptLight->afCascadeSplits[uCascade];
ptShadowData->tCascadeSplits.d[uCascade] = ptLight->afCascadeSplits[uCascade];

plVec3 atCameraCorners[] = {
{ -1.0f, 1.0f, 1.0f },
{ -1.0f, -1.0f, 1.0f },
{ 1.0f, -1.0f, 1.0f },
{ 1.0f, 1.0f, 1.0f },
{ -1.0f, 1.0f, 0.0f },
{ -1.0f, -1.0f, 0.0f },
{ 1.0f, -1.0f, 0.0f },
{ 1.0f, 1.0f, 0.0f },
// camera space
plVec3 atCameraCorners2[] = {
{ -fLastSplitDist * s / g, fLastSplitDist / g, fLastSplitDist },
{ -fLastSplitDist * s / g, -fLastSplitDist / g, fLastSplitDist },
{ fLastSplitDist * s / g, -fLastSplitDist / g, fLastSplitDist },
{ fLastSplitDist * s / g, fLastSplitDist / g, fLastSplitDist },
{ -fSplitDist * s / g, fSplitDist / g, fSplitDist },
{ -fSplitDist * s / g, -fSplitDist / g, fSplitDist },
{ fSplitDist * s / g, -fSplitDist / g, fSplitDist },
{ fSplitDist * s / g, fSplitDist / g, fSplitDist },
};
// plMat4 tCameraInversion = pl_mul_mat4(&tCameraProjMat, &ptSceneCamera->tViewMat);
plMat4 tCameraInversion = pl_mul_mat4(&ptSceneCamera->tProjMat, &ptSceneCamera->tViewMat);
tCameraInversion = pl_mat4_invert(&tCameraInversion);

// find max diagonal
float fD0 = ceilf(pl_length_vec3(pl_sub_vec3(atCameraCorners2[0], atCameraCorners2[6])));
float fD1 = ceilf(pl_length_vec3(pl_sub_vec3(atCameraCorners2[6], atCameraCorners2[4])));
float fD = pl_max(fD0, fD1) * 1.0f;
const float fUnitPerTexel = fD / (float)ptLight->uShadowResolution;

plMat4 tCameraInversion = pl_mat4_invert(&ptSceneCamera->tViewMat);

// convert to world space
for(uint32_t i = 0; i < 8; i++)
{
plVec4 tInvCorner = pl_mul_mat4_vec4(&tCameraInversion, (plVec4){.xyz = atCameraCorners[i], .w = 1.0f});
atCameraCorners[i] = pl_div_vec3_scalarf(tInvCorner.xyz, tInvCorner.w);
plVec4 tInvCorner = pl_mul_mat4_vec4(&tCameraInversion, (plVec4){.xyz = atCameraCorners2[i], .w = 1.0f});
atCameraCorners2[i] = tInvCorner.xyz;
}

for(uint32_t i = 0; i < 4; i++)
// convert to light space
plCameraComponent tShadowCamera = {
.tType = PL_CAMERA_TYPE_ORTHOGRAPHIC
};
gptCamera->look_at(&tShadowCamera, (plVec3){0}, tDirection);
tShadowCamera.fWidth = fD;
tShadowCamera.fHeight = fD;
tShadowCamera.fNearZ = 0.0f;
tShadowCamera.fFarZ = fD;
gptCamera->update(&tShadowCamera);

for(uint32_t i = 0; i < 8; i++)
{
const plVec3 tDist = pl_sub_vec3(atCameraCorners[i + 4], atCameraCorners[i]);
atCameraCorners[i + 4] = pl_add_vec3(atCameraCorners[i], pl_mul_vec3_scalarf(tDist, fSplitDist));
atCameraCorners[i] = pl_add_vec3(atCameraCorners[i], pl_mul_vec3_scalarf(tDist, fLastSplitDist));
plVec4 tInvCorner = pl_mul_mat4_vec4(&tShadowCamera.tViewMat, (plVec4){.xyz = atCameraCorners2[i], .w = 1.0f});
atCameraCorners2[i] = tInvCorner.xyz;
}

// get frustum center
plVec3 tFrustumCenter = {0};
// find center
float fXMin = FLT_MAX;
float fXMax = -FLT_MAX;
float fYMin = FLT_MAX;
float fYMax = -FLT_MAX;
float fZMin = FLT_MAX;
float fZMax = -FLT_MAX;
for(uint32_t i = 0; i < 8; i++)
tFrustumCenter = pl_add_vec3(tFrustumCenter, atCameraCorners[i]);
tFrustumCenter = pl_div_vec3_scalarf(tFrustumCenter, 8.0f);

float fRadius = 0.0f;
for (uint32_t i = 0; i < 8; i++)
{
float fDistance = pl_length_vec3(pl_sub_vec3(atCameraCorners[i], tFrustumCenter));
fRadius = pl_max(fRadius, fDistance);
fXMin = pl_min(atCameraCorners2[i].x, fXMin);
fYMin = pl_min(atCameraCorners2[i].y, fYMin);
fZMin = pl_min(atCameraCorners2[i].z, fZMin);
fXMax = pl_max(atCameraCorners2[i].x, fXMax);
fYMax = pl_max(atCameraCorners2[i].y, fYMax);
fZMax = pl_max(atCameraCorners2[i].z, fZMax);
}
fRadius = ceilf(fRadius * 16.0f) / 16.0f;

plVec3 tDirection = ptLight->tDirection;
plVec4 tLightPosLightSpace = {
fUnitPerTexel * floorf((fXMax + fXMin) / (fUnitPerTexel * 2.0f)),
fUnitPerTexel * floorf((fYMax + fYMin) / (fUnitPerTexel * 2.0f)),
fZMin,
1.0f
};

tDirection = pl_norm_vec3(tDirection);
plVec3 tEye = pl_sub_vec3(tFrustumCenter, pl_mul_vec3_scalarf(tDirection, fRadius + 50.0f));

plCameraComponent tShadowCamera = {
.tType = PL_CAMERA_TYPE_ORTHOGRAPHIC
};
gptCamera->look_at(&tShadowCamera, tEye, tFrustumCenter);
tShadowCamera.fWidth = fRadius * 2.0f;
tShadowCamera.fHeight = fRadius * 2.0f;
tShadowCamera.fNearZ = 0.0f;
tShadowCamera.fFarZ = fRadius * 2.0f + 50.0f;
plMat4 tLightInversion = pl_mat4_invert(&tShadowCamera.tViewMat);
plVec4 tLightPos = pl_mul_mat4_vec4(&tLightInversion, (plVec4){.xyz = tLightPosLightSpace.xyz, .w = 1.0f});

gptCamera->look_at(&tShadowCamera, tLightPos.xyz, pl_add_vec3(tLightPos.xyz, tDirection));
gptCamera->update(&tShadowCamera);
// tShadowCamera.fAspectRatio = 1.0f;
// tShadowCamera.fFieldOfView = atan2f(fRadius, (fRadius + 50.0f));
// tShadowCamera.fNearZ = 0.01f;
fLastSplitDist = fSplitDist;

// tShadowCamera.tProjMat.col[2].z *= -1.0f;
atCamViewProjs[uCascade] = pl_mul_mat4(&tShadowCamera.tProjMat, &tShadowCamera.tViewMat);

ptShadowData->viewProjMat[uCascade] = atCamViewProjs[uCascade];
fLastSplitDist = fSplitDist;
}

char* pcBufferStart = gptGfx->get_buffer(ptDevice, ptView->atDShadowCameraBuffers[uFrameIdx])->tMemoryAllocation.pHostMapped;
Expand Down Expand Up @@ -2246,6 +2258,7 @@ pl_refr_create_global_shaders(void)
.tVertexShader = tVertexShader,
.tGraphicsState = {
.ulDepthWriteEnabled = 1,
.ulDepthClampEnabled = 1,
.ulDepthMode = PL_COMPARE_MODE_GREATER_OR_EQUAL,
.ulCullMode = PL_CULL_MODE_NONE,
.ulWireframe = 0,
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2 changes: 1 addition & 1 deletion sandbox/app.c
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Original file line number Diff line number Diff line change
Expand Up @@ -180,7 +180,7 @@ pl_app_load(plApiRegistryI* ptApiRegistry, plEditorData* ptEditorData)

// create main camera
plCameraComponent* ptMainCamera = NULL;
ptEditorData->tMainCamera = gptEcs->create_perspective_camera(ptMainComponentLibrary, "main camera", (plVec3){-4.7f, 4.2f, -3.256f}, PL_PI_3, ptIO->tMainViewportSize.x / ptIO->tMainViewportSize.y, 0.1f, 148.0f, true, &ptMainCamera);
ptEditorData->tMainCamera = gptEcs->create_perspective_camera(ptMainComponentLibrary, "main camera", (plVec3){-4.7f, 4.2f, -3.256f}, PL_PI_3, ptIO->tMainViewportSize.x / ptIO->tMainViewportSize.y, 0.1f, 48.0f, true, &ptMainCamera);
gptCamera->set_pitch_yaw(ptMainCamera, 0.0f, 0.911f);
gptCamera->update(ptMainCamera);
gptEcs->attach_script(ptMainComponentLibrary, "pl_script_camera", PL_SCRIPT_FLAG_PLAYING, ptEditorData->tMainCamera, NULL);
Expand Down

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