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ADD: stabilized CSM

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hydrogendeuteride
2025-10-22 10:35:32 +09:00
parent 4dec20b60f
commit f3bdb58f1a
1 changed files with 62 additions and 66 deletions
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124
src/scene/vk_scene.cpp
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@@ -121,8 +121,8 @@ void SceneManager::update_scene()
glm::vec3 right = glm::normalize(glm::cross(upPick, L));
glm::vec3 up = glm::normalize(glm::cross(L, right));
const float csmFar = kShadowCSMFar; // configurable shadow distance
const float lambda = 0.5f; // split weighting
const float csmFar = kShadowCSMFar;
const float lambda = 0.5f;
const int cascades = kShadowCascadeCount;
float splits[4] = {0, 0, 0, 0};
@@ -138,84 +138,81 @@ void SceneManager::update_scene()
mat4 invView = inverse(view);
auto buildCascade = [&](float nearD, float farD) -> mat4 {
// Frustum in view-space (RH, forward -Z)
float tanHalfFov = tanf(fov * 0.5f);
float yn = tanHalfFov * nearD;
float xn = yn * aspect;
float yf = tanHalfFov * farD;
float xf = yf * aspect;
float baseWorldTexel = 0.0f;
vec3 cornersV[8] = {
{-xn, -yn, -nearD}, {xn, -yn, -nearD}, {xn, yn, -nearD}, {-xn, yn, -nearD},
{-xf, -yf, -farD}, {xf, -yf, -farD}, {xf, yf, -farD}, {-xf, yf, -farD}
};
vec3 cornersW[8];
vec3 centerWS(0.0f);
auto buildCascade = [&](int idx, float nearD, float farD) -> mat4 {
float tanHalf = tanf(fov * 0.5f);
float yf = tanHalf * farD;
float xf = yf * aspect;
float rStable = 1.05f * sqrtf(xf * xf + yf * yf);
float texelWorld;
if (idx == 0)
{
baseWorldTexel = (2.0f * rStable) / kShadowMapResolution;
baseWorldTexel = powf(2.0f, ceilf(log2f(baseWorldTexel)));
texelWorld = baseWorldTexel;
}
else
{
texelWorld = baseWorldTexel * (1 << idx);
rStable = 0.5f * texelWorld * kShadowMapResolution;
}
vec3 cornersV[8]; {
float tanHalfFov = tanf(fov * 0.5f);
float yn = tanHalfFov * nearD, xn = yn * aspect;
float yf = tanHalfFov * farD, xf = yf * aspect;
cornersV[0] = {-xn, -yn, -nearD};
cornersV[1] = {xn, -yn, -nearD};
cornersV[2] = {xn, yn, -nearD};
cornersV[3] = {-xn, yn, -nearD};
cornersV[4] = {-xf, -yf, -farD};
cornersV[5] = {xf, -yf, -farD};
cornersV[6] = {xf, yf, -farD};
cornersV[7] = {-xf, yf, -farD};
}
mat4 invView = inverse(view);
vec3 cornersW[8], centerWS(0);
for (int i = 0; i < 8; ++i)
{
vec3 w = vec3(invView * vec4(cornersV[i], 1.0f));
cornersW[i] = w;
centerWS += w;
cornersW[i] = vec3(invView * vec4(cornersV[i], 1));
centerWS += cornersW[i];
}
centerWS *= (1.0f / 8.0f);
centerWS *= 1.0f / 8.0f;
// Initial light view
const float lightDist = 100.0f;
float lightDist = rStable + 50.0f;
vec3 lightPos = centerWS - L * lightDist;
mat4 viewLight = lookAtRH(lightPos, centerWS, up);
// Compute symmetric bounds around center in light space
vec2 centerLS = vec2(viewLight * vec4(centerWS, 1.0f));
float minZ = 1e9f, maxZ = -1e9f;
float radius = 0.0f;
for (int i = 0; i < 8; ++i)
{
vec3 p = vec3(viewLight * vec4(cornersW[i], 1.0f));
minZ = std::min(minZ, p.z);
maxZ = std::max(maxZ, p.z);
radius = std::max(radius, glm::length(vec2(p.x, p.y) - centerLS));
}
// Pad extents
radius *= 1.05f;
float sliceLen = farD - nearD;
float zPad = std::max(50.0f, 0.2f * sliceLen);
// Two-sided along light direction: include casters between light and slice
float nearLS = 0.01f;
float farLS = -minZ + zPad;
// Stabilize by snapping to shadow texel grid
float texelSize = (2.0f * radius) / kShadowMapResolution;
vec2 snapped = floor(centerLS / texelSize) * texelSize;
vec2 centerLS = vec2(viewLight * vec4(centerWS, 1));
vec2 snapped = floor(centerLS / texelWorld) * texelWorld;
vec2 deltaLS = snapped - centerLS;
vec3 shiftWS = right * deltaLS.x + up * deltaLS.y;
vec3 centerSnapped = centerWS + shiftWS;
vec3 lightPosSnapped = centerSnapped - L * lightDist;
viewLight = lookAtRH(lightPosSnapped, centerSnapped, up);
// Recompute z-range with snapped view
centerLS = vec2(viewLight * vec4(centerSnapped, 1.0f));
minZ = 1e9f; maxZ = -1e9f; radius = 0.0f;
lightPos = centerSnapped - L * lightDist;
viewLight = lookAtRH(lightPos, centerSnapped, up);
float radius = ceil(rStable / texelWorld) * texelWorld;
vec2 cLS = vec2(viewLight * vec4(centerSnapped, 1));
float left = cLS.x - radius, rightE = cLS.x + radius;
float bottom = cLS.y - radius, top = cLS.y + radius;
float minZ = 1e9f, maxZ = -1e9f;
for (int i = 0; i < 8; ++i)
{
vec3 p = vec3(viewLight * vec4(cornersW[i], 1.0f));
vec3 p = vec3(viewLight * vec4(cornersW[i], 1));
minZ = std::min(minZ, p.z);
maxZ = std::max(maxZ, p.z);
radius = std::max(radius, glm::length(vec2(p.x, p.y) - centerLS));
}
// Keep near plane close to the light to include forward casters
nearLS = 0.01f;
farLS = -minZ + zPad;
float sliceLen = farD - nearD;
float zPad = std::max(10.0f, 0.2f * sliceLen);
float casterExtrude = 100.0f;
float nearLS = 0.01f;
float farLS = -minZ + zPad + casterExtrude;
float left = centerLS.x - radius;
float rightE = centerLS.x + radius;
float bottom = centerLS.y - radius;
float top = centerLS.y + radius;
mat4 projLight = orthoRH_ZO(-40.f, 40.f, -40.f, 40.f, nearLS, farLS);
// projLight[1][1] *= -1.0f;
mat4 projLight = orthoRH_ZO(left, rightE, bottom, top, nearLS, farLS);
return projLight * viewLight;
};
@@ -223,9 +220,8 @@ void SceneManager::update_scene()
{
float nearD = (i == 0) ? nearPlane : splits[i - 1];
float farD = splits[i];
sceneData.lightViewProjCascades[i] = buildCascade(nearD, farD);
sceneData.lightViewProjCascades[i] = buildCascade(i, nearD, farD);
}
// For legacy paths, keep first cascade in single matrix
sceneData.lightViewProj = sceneData.lightViewProjCascades[0];
}