From e737a7d0d64d0d56a65ab8fc7a9ad9feef7dd482 Mon Sep 17 00:00:00 2001
From: Jere Tuliniemi <jere.tuliniemi@qt.io>
Date: Thu, 16 Apr 2020 13:01:24 +0300
Subject: [PATCH] Limit directional shadow map frustum to scene bounds
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If using scene bounds creates a smaller shadow map camera frustum, use
that.
Task-number: QTBUG-83362
Change-Id: I77b261cfe07aca9a238b907ece842d6f5266a395
Reviewed-by: Antti Määttä <antti.maatta@qt.io>
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
---
.../qssgrendererimpllayerrenderdata.cpp | 101 ++++++++++++------
1 file changed, 70 insertions(+), 31 deletions(-)
diff --git a/src/runtimerender/rendererimpl/qssgrendererimpllayerrenderdata.cpp b/src/runtimerender/rendererimpl/qssgrendererimpllayerrenderdata.cpp
index 98b22899f..6f0437229 100644
--- a/src/runtimerender/rendererimpl/qssgrendererimpllayerrenderdata.cpp
+++ b/src/runtimerender/rendererimpl/qssgrendererimpllayerrenderdata.cpp
@@ -354,12 +354,43 @@ void computeFrustumBounds(const QSSGRenderCamera &inCamera, const QRectF &inView
ctrBound *= 0.125f;
}
+QSSGBounds3 calculateShadowCameraBoundingBox(const QVector3D *points, const QVector3D &forward,
+ const QVector3D &up, const QVector3D &right)
+{
+ float minDistanceZ = std::numeric_limits<float>::max();
+ float maxDistanceZ = -std::numeric_limits<float>::max();
+ float minDistanceY = std::numeric_limits<float>::max();
+ float maxDistanceY = -std::numeric_limits<float>::max();
+ float minDistanceX = std::numeric_limits<float>::max();
+ float maxDistanceX = -std::numeric_limits<float>::max();
+ for (int i = 0; i < 8; ++i) {
+ float distanceZ = QVector3D::dotProduct(points[i], forward);
+ if (distanceZ < minDistanceZ)
+ minDistanceZ = distanceZ;
+ if (distanceZ > maxDistanceZ)
+ maxDistanceZ = distanceZ;
+ float distanceY = QVector3D::dotProduct(points[i], up);
+ if (distanceY < minDistanceY)
+ minDistanceY = distanceY;
+ if (distanceY > maxDistanceY)
+ maxDistanceY = distanceY;
+ float distanceX = QVector3D::dotProduct(points[i], right);
+ if (distanceX < minDistanceX)
+ minDistanceX = distanceX;
+ if (distanceX > maxDistanceX)
+ maxDistanceX = distanceX;
+ }
+ return QSSGBounds3(QVector3D(minDistanceX, minDistanceY, minDistanceZ),
+ QVector3D(maxDistanceX, maxDistanceY, maxDistanceZ));
+}
+
void setupCameraForShadowMap(const QVector2D &/*inCameraVec*/,
QSSGRenderContext & /*inContext*/,
const QRectF &inViewport,
const QSSGRenderCamera &inCamera,
const QSSGRenderLight *inLight,
- QSSGRenderCamera &theCamera)
+ QSSGRenderCamera &theCamera,
+ QVector3D *scenePoints = nullptr)
{
// setup light matrix
quint32 mapRes = 1 << inLight->m_shadowMapRes;
@@ -374,8 +405,15 @@ void setupCameraForShadowMap(const QVector2D &/*inCameraVec*/,
theCamera.fov = qDegreesToRadians(90.f);
if (inLight->m_lightType == QSSGRenderLight::Type::Directional) {
- QVector3D frustBounds[8], boundCtr;
- computeFrustumBounds(inCamera, inViewport, boundCtr, frustBounds);
+ QVector3D frustumPoints[8], boundCtr, sceneCtr;
+ computeFrustumBounds(inCamera, inViewport, boundCtr, frustumPoints);
+
+ if (scenePoints) {
+ sceneCtr = QVector3D(0, 0, 0);
+ for (int i = 0; i < 8; ++i)
+ sceneCtr += scenePoints[i];
+ sceneCtr *= 0.125f;
+ }
QVector3D forward = inLightDir;
forward.normalize();
@@ -389,37 +427,24 @@ void setupCameraForShadowMap(const QVector2D &/*inCameraVec*/,
up.normalize();
// Calculate bounding box of the scene camera frustum
- float minDistanceZ = std::numeric_limits<float>::max();
- float maxDistanceZ = -std::numeric_limits<float>::max();
- float minDistanceY = std::numeric_limits<float>::max();
- float maxDistanceY = -std::numeric_limits<float>::max();
- float minDistanceX = std::numeric_limits<float>::max();
- float maxDistanceX = -std::numeric_limits<float>::max();
- for (int i = 0; i < 8; ++i) {
- float distanceZ = QVector3D::dotProduct(frustBounds[i], forward);
- if (distanceZ < minDistanceZ)
- minDistanceZ = distanceZ;
- if (distanceZ > maxDistanceZ)
- maxDistanceZ = distanceZ;
- float distanceY = QVector3D::dotProduct(frustBounds[i], up);
- if (distanceY < minDistanceY)
- minDistanceY = distanceY;
- if (distanceY > maxDistanceY)
- maxDistanceY = distanceY;
- float distanceX = QVector3D::dotProduct(frustBounds[i], right);
- if (distanceX < minDistanceX)
- minDistanceX = distanceX;
- if (distanceX > maxDistanceX)
- maxDistanceX = distanceX;
+ QSSGBounds3 bounds = calculateShadowCameraBoundingBox(frustumPoints, forward, up, right);
+ inLightPos = boundCtr;
+ if (scenePoints) {
+ QSSGBounds3 sceneBounds = calculateShadowCameraBoundingBox(scenePoints, forward, up,
+ right);
+ if (sceneBounds.extents().x() * sceneBounds.extents().y() * sceneBounds.extents().z()
+ < bounds.extents().x() * bounds.extents().y() * bounds.extents().z()) {
+ bounds = sceneBounds;
+ inLightPos = sceneCtr;
+ }
}
// Apply bounding box parameters to shadow map camera projection matrix
// so that the whole scene is fit inside the shadow map
- inLightPos = boundCtr;
- theViewport.setHeight(std::abs(maxDistanceY - minDistanceY));
- theViewport.setWidth(std::abs(maxDistanceX - minDistanceX));
- theCamera.clipNear = -std::abs(maxDistanceZ - minDistanceZ);
- theCamera.clipFar = std::abs(maxDistanceZ - minDistanceZ);
+ theViewport.setHeight(bounds.extents().y() * 2);
+ theViewport.setWidth(bounds.extents().x() * 2);
+ theCamera.clipNear = -bounds.extents().z() * 2;
+ theCamera.clipFar = bounds.extents().z() * 2;
}
theCamera.flags.setFlag(QSSGRenderCamera::Flag::Orthographic, inLight->m_lightType == QSSGRenderLight::Type::Directional);
@@ -693,16 +718,30 @@ void QSSGLayerRenderData::renderShadowMapPass(QSSGResourceFrameBuffer *theFB)
QSSGRenderClearFlags clearFlags(QSSGRenderClearValues::Depth | QSSGRenderClearValues::Stencil
| QSSGRenderClearValues::Color);
+ auto bounds = camera->parent->getBounds(renderer->contextInterface()->bufferManager());
+
+ QVector3D scenePoints[8];
+ scenePoints[0] = bounds.minimum;
+ scenePoints[1] = QVector3D(bounds.maximum.x(), bounds.minimum.y(), bounds.minimum.z());
+ scenePoints[2] = QVector3D(bounds.minimum.x(), bounds.maximum.y(), bounds.minimum.z());
+ scenePoints[3] = QVector3D(bounds.maximum.x(), bounds.maximum.y(), bounds.minimum.z());
+ scenePoints[4] = QVector3D(bounds.minimum.x(), bounds.minimum.y(), bounds.maximum.z());
+ scenePoints[5] = QVector3D(bounds.maximum.x(), bounds.minimum.y(), bounds.maximum.z());
+ scenePoints[6] = QVector3D(bounds.minimum.x(), bounds.maximum.y(), bounds.maximum.z());
+ scenePoints[7] = bounds.maximum;
+
for (int i = 0; i < globalLights.size(); i++) {
// don't render shadows when not casting
if (!globalLights[i]->m_castShadow)
continue;
+
QSSGShadowMapEntry *pEntry = shadowMapManager->getShadowMapEntry(i);
if (pEntry && pEntry->m_depthMap && pEntry->m_depthCopy && pEntry->m_depthRender) {
QSSGRenderCamera theCamera;
QVector2D theCameraProps = QVector2D(camera->clipNear, camera->clipFar);
- setupCameraForShadowMap(theCameraProps, *renderer->context(), __viewport.m_initialValue, *camera, globalLights[i], theCamera);
+ setupCameraForShadowMap(theCameraProps, *renderer->context(), __viewport.m_initialValue,
+ *camera, globalLights[i], theCamera, scenePoints);
// we need this matrix for the final rendering
theCamera.calculateViewProjectionMatrix(pEntry->m_lightVP);
pEntry->m_lightView = theCamera.globalTransform.inverted();
--
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