AABB3::operator OBB3() const {
Vector3 siz = max - min;
return OBB3(Matrix4(siz.x, 0, 0, 0,
0, siz.y, 0, 0,
0, 0, siz.z, 0,
min.x, min.y, min.z, 1));
}
void GLBasicShadowMapRenderer::BuildMatrix(float near, float far){
// TODO: variable light direction?
Vector3 lightDir = MakeVector3(0, -1, -1).Normalize();
// set better up dir?
Vector3 up = MakeVector3(0, 0, 1);
Vector3 side = Vector3::Cross(up, lightDir).Normalize();
up = Vector3::Cross(lightDir, side).Normalize();
// build frustrum
client::SceneDefinition def = GetRenderer()->GetSceneDef();
Vector3 frustrum[8];
float tanX = tanf(def.fovX * .5f);
float tanY = tanf(def.fovY * .5f);
frustrum[0] = FrustrumCoord(def, tanX, tanY, near);
frustrum[1] = FrustrumCoord(def, tanX, -tanY, near);
frustrum[2] = FrustrumCoord(def, -tanX, tanY, near);
frustrum[3] = FrustrumCoord(def, -tanX, -tanY, near);
frustrum[4] = FrustrumCoord(def, tanX, tanY, far);
frustrum[5] = FrustrumCoord(def, tanX, -tanY, far);
frustrum[6] = FrustrumCoord(def, -tanX, tanY, far);
frustrum[7] = FrustrumCoord(def, -tanX, -tanY, far);
// compute frustrum's x,y boundary
float minX, maxX, minY, maxY;
minX = maxX = Vector3::Dot(frustrum[0], side);
minY = maxY = Vector3::Dot(frustrum[0], up);
for(int i = 1; i < 8; i++){
float x = Vector3::Dot(frustrum[i], side);
float y = Vector3::Dot(frustrum[i], up);
if(x < minX) minX = x;
if(x > maxX) maxX = x;
if(y < minY) minY = y;
if(y > maxY) maxY = y;
}
// compute frustrum's z boundary
Segment seg;
Plane3 plane1(0,0,1,-4.f);
Plane3 plane2(0,0,1,64.f);
seg += ZRange(side * minX + up * minY,
lightDir, plane1, plane2);
seg += ZRange(side * minX + up * maxY,
lightDir, plane1, plane2);
seg += ZRange(side * maxX + up * minY,
lightDir, plane1, plane2);
seg += ZRange(side * maxX + up * maxY,
lightDir, plane1, plane2);
for(int i = 1; i < 8; i++){
seg += Vector3::Dot(frustrum[i], lightDir);
}
// build frustrum obb
Vector3 origin = side * minX + up * minY + lightDir * seg.low;
Vector3 axis1 = side * (maxX - minX);
Vector3 axis2 = up * (maxY - minY);
Vector3 axis3 = lightDir * (seg.high - seg.low);
obb = OBB3(Matrix4::FromAxis(axis1, axis2, axis3,
origin));
vpWidth = 2.f / axis1.GetLength();
vpHeight = 2.f / axis2.GetLength();
// convert to projectionview matrix
matrix = obb.m.InversedFast();
matrix = Matrix4::Scale(2.f) * matrix;
matrix = Matrix4::Translate(-1, -1, -1) * matrix;
// scale a little big for padding
matrix = Matrix4::Scale(.98f) * matrix;
//
matrix = Matrix4::Scale(1,1,-1) * matrix;
// make sure frustrums in range
#ifndef NDEBUG
for(int i = 0; i < 8; i++){
Vector4 v = matrix * frustrum[i];
SPAssert(v.x >= -1.f);
SPAssert(v.y >= -1.f);
//SPAssert(v.z >= -1.f);
SPAssert(v.x < 1.f);
SPAssert(v.y < 1.f);
//SPAssert(v.z < 1.f);
}
#endif
}
