/////////////
// Methods //
/////////////
color environmentMap::evaluate(const ray& r) const
{
// inverse transform the ray
ray transformedRay(r);
transformedRay.inverseTransform(_transformation);
// convert ray direction to texture coordinate
float theta = acos(transformedRay.direction().z);
float phi = atan2(transformedRay.direction().y, transformedRay.direction().x);
if(phi < 0.0f) phi += 2.0f * M_PI;
theta /= M_PI;
phi /= 2.0f * M_PI;
// get texel coordinate
float texelU = std::min(phi * (_texture.width()-1), (float)(_texture.width()-1));
float texelV = std::min(theta * (_texture.height()-1), (float)(_texture.height()-1));
// compute corners
float left = floor(texelU);
float right = ceil(texelU);
float top = floor(texelV);
float bottom = ceil(texelV);
// linear interpolate along X
float w = texelU - left;
color topColor = _texture(left,top)*(1.0f-w) + _texture(right,top)*w;
color bottomColor = _texture(left,bottom)*(1.0f-w) + _texture(right,bottom)*w;
// linear interlate along Y
w = texelV - top;
return (1.0f - w)*topColor + w*bottomColor;
}
bool Transform::intersect(const Ray &r, Hit &h, float tmin)
{
Vec3f original = r.getOrigin();
Vec3f dir = r.getDirection();
mReverseMat.Transform(original);
mReverseMat.TransformDirection(dir);
Ray transformedRay(original, dir);
if (mObj->intersect(transformedRay, h, tmin))
{
Vec3f normal = h.getNormal();
Matrix t;
mReverseMat.Transpose(t);
t.TransformDirection(normal);
h.set(h.getT(), h.getMaterial(), normal, r);
return true;
}
return false;
}
