Aparent 2D position of a directional light.

[Mel]

This code projects the aparent 2D position of a directional light, so you can know the center of a lens flare simulating the sun, for instance. You need the light direction, and it will provide the result as a vector 2D in which the visible space is in the range (0,1), so, you can, after, multiply it by the screen resolution to find the proper place in screen space.

Code: Select all

 
core::vector2df projectVectorTo2DCoordinates(core::vector3df v,scene::ICameraSceneNode* cam){
core::matrix viewProjection;
core::vector3df ligthDir,viewDir;
core::vector2df screenPos;
f32 vect[4];
 
viewDir = cam->getTarget()-cam->getAbsolutePosition();
viewDir.normalize();
 
lightDir = v;
lightDir.normalize();
 
viewProjection = cam->getProjectionMatrix();
viewProjection *= core::matrix4().buildCameraLookAtMatrixLH(core::vector3df(0,0,0),viewDir,cam->getUpVector()); 
//use RH if needed, instead, it must match the projection matrix of the camera, though...
 
viewProjection.transformVect(vect,lightDir);
screenPos.X = vect[0]/vect[3];
screenPos.Y = -vect[1]/vect[3];
 
screenPos = 2*screenPos - core::vector2df(1,1);
 
return screenPos;
}