rendering::ShadowCameraTransform rendering::lighting::DirectionalLight::CalcShadowCameraTransform(const math::Vector3D& cameraPos, const math::Quaternion& cameraRot) const
{
//return BaseLight::CalcShadowCameraTransform(cameraPos, cameraRot);
// This function in directional light allows the directional light to be casting shadows only in the area around the camera current position
ShadowCameraTransform shadowCameraTransform(cameraPos + cameraRot.GetForward() * m_halfShadowArea, GetTransform().GetTransformedRot());
/**
* The reoccurring shimmering is caused by the moving shadow camera by the value less than
* the shadow map texel size. If I move by, let's say, half the texel size, render the scene
* and generate the shadow map again, the objects aren't going to map to exactly the same texels
* in the shadow map. This causes approximation to be calculated slightly differently each frame.
* To fix the shimmering effect we have to make sure we only move by the multiple of the texel size.
*/
/* ==================== Fixing the shimmering effect begin ==================== */
const auto shadowMapSize = static_cast<math::Real>(1 << GetShadowInfo()->GetShadowMapSizeAsPowerOf2());
const auto worldSpaceShadowMapTexelSize = m_halfShadowArea * 2.0f / shadowMapSize;
// Now we transform from the world space into the light space
auto lightSpaceCameraPos(shadowCameraTransform.pos.Rotate(shadowCameraTransform.rot.Conjugate()));
// Now we need to snap the lightSpaceCameraPos to shadow map texel size increments
lightSpaceCameraPos.x = worldSpaceShadowMapTexelSize * math::Floor(lightSpaceCameraPos.x / worldSpaceShadowMapTexelSize);
lightSpaceCameraPos.y = worldSpaceShadowMapTexelSize * math::Floor(lightSpaceCameraPos.y / worldSpaceShadowMapTexelSize);
// Now we transform back from the light space into the world space
shadowCameraTransform.pos = lightSpaceCameraPos.Rotate(shadowCameraTransform.rot);
/* ==================== Fixing the shimmering effect end ==================== */
return shadowCameraTransform;
}
ShadowCameraTransform DirectionalLight::CalcShadowCameraTransform(const Vector3f& mainCameraPos, const Quaternion& mainCameraRot) const
{
Vector3f resultPos = mainCameraPos + mainCameraRot.GetForward() * GetHalfShadowArea();
Quaternion resultRot = GetTransform().GetTransformedRot();
float worldTexelSize = (GetHalfShadowArea()*2)/((float)(1 << GetShadowInfo().GetShadowMapSizeAsPowerOf2()));
Vector3f lightSpaceCameraPos = resultPos.Rotate(resultRot.Conjugate());
lightSpaceCameraPos.SetX(worldTexelSize * floor(lightSpaceCameraPos.GetX() / worldTexelSize));
lightSpaceCameraPos.SetY(worldTexelSize * floor(lightSpaceCameraPos.GetY() / worldTexelSize));
resultPos = lightSpaceCameraPos.Rotate(resultRot);
return ShadowCameraTransform(resultPos, resultRot);
}
