private void ComputeVisibility(Ray r, IntersectionRecord rec, int exceptGeomIndex)
{
#if KDTREE
mKdTree.ComputeVisibility(r, rec, exceptGeomIndex);
#else
for (int i = 0; i < mSceneDatabase.GetNumGeom(); i++)
{
if (i != exceptGeomIndex)
{
RTGeometry g = mSceneDatabase.GetGeom(i);
g.Intersect(r, rec);
}
}
#endif
}
private const float kDepthImageDist = 1f; // depth map image plane distance from the light source
private void InitDepthMap(SceneDatabase sceneDatabase)
{
if (null != mDepthMap)
{
return; // done
}
// remember!! mDireciton is L, or a vector from Visible point to the light.
// Here we want direction from light source towards the scene
Vector3 useDir = -mDirection;
// 1. Find a Up direction
// guess up direction to be (0, 1, 0), if view direction is also this,
// use (1, 0, 0) as view direction
Vector3 up = Vector3.UnitY;
if (Math.Abs(Vector3.Dot(up, useDir)) > 0.99999)
{
up = Vector3.UnitX;
}
// 2. define Orthonormal base
Vector3 sideV = Vector3.Cross(up, useDir);
up = Vector3.Cross(useDir, sideV);
sideV.Normalize();
up.Normalize();
// 3. compute the depth map image plane,
// define the image plane to be located at ... a distance of kDepthImageDist away
Vector3 ptOnImage = mPosition + kDepthImageDist * useDir;
// 4. compute depth map image size
float halfImageSize = kDepthImageDist * (float)Math.Tan(mOuterAngle / 2f);
// 5. Compute the 4 vertices the defines the depth map
Vector3[] v = new Vector3[4];
v[0] = ptOnImage - halfImageSize * up - halfImageSize * sideV;
v[1] = ptOnImage - halfImageSize * up + halfImageSize * sideV;
v[2] = ptOnImage + halfImageSize * up + halfImageSize * sideV;
v[3] = ptOnImage + halfImageSize * up - halfImageSize * sideV;
// 6. create a Geometry that represents the map
// ** Be caureful **!!
// RTRectangle uses v[0] as the origin for texture lookup
// we _MUST_ follow the same in order to take advante of GetUV() function!
mDepthMapGeom = new RTRectangle(v);
// 7. Now allocate memory for the actual map
mDepthMap = new float[mRes][];
mGeomID = new int[mRes][];
for (int i = 0; i < mRes; i++)
{
mDepthMap[i] = new float[mRes];
mGeomID[i] = new int[mRes];
}
// now, trace rays through each of the pixels in the depth map and record the depth and geomID
float pixelSize = halfImageSize / (0.5f * mRes);
Vector3 upPixelVector = pixelSize * up;
Vector3 sidePixelVector = pixelSize * sideV;
for (int y = 0; y < mRes; y++)
{
Vector3 yDisp = v[0] + (y + 0.5f) * upPixelVector;
for (int x = 0; x < mRes; x++)
{
Vector3 pixelPos = ((x + 0.5f) * sidePixelVector) + yDisp;
Ray r = new Ray(mPosition, pixelPos);
IntersectionRecord rec = new IntersectionRecord();
for (int i = 0; i < sceneDatabase.GetNumGeom(); i++)
{
RTGeometry g = sceneDatabase.GetGeom(i);
g.Intersect(r, rec);
}
mDepthMap[x][y] = rec.HitDistance;
// closes intersection distance, any object that is
// further away from the light than this distance is in the shadow of this light
mGeomID[x][y] = rec.GeomIndex;
// this object can never be in shadow, becuase it is the closest to the light!
}
}
}