I must be able to select a 3D object in a simple seen from a click. To do that I use Processing and OBJLoader (to load the models) but my issue is in one of the algorithm. Every model has a simple BoundingBox always aligned with the world.

This is how I get the ray :

public Ray getRayFromClick(int mouse_x, int mouse_y){ //3d normalized device coordinates 
float x = (2.0f * mouse_x) / width - 1.0f; float y = 1.0f - (2.0f * mouse_y) / height; 
float z = 1.0f; PVector ray_nds = new PVector(x, y, z);
//4d Homogeneous Clip Coordinates
float[] ray_clip = new float[4];
ray_clip[0]=ray_nds.x;
ray_clip[1]=ray_nds.y;
ray_clip[2]=-1;ray_clip[3]=1.0;

//4d Eye (Camera) Coordinates
float[] ray_eye = new float[4];
PMatrix proj_inv = p3d.projection.get();
proj_inv.invert();
proj_inv.mult(ray_clip,ray_eye);
ray_eye[2]=-1.0;ray_eye[3]=0.0;

//4d World Coordinates
float[] ray_wor4d = new float[4];
PVector ray_wor = new PVector();
p3d.modelviewInv.get().mult(ray_eye,ray_wor4d);
ray_wor.set(ray_wor4d[0],ray_wor4d[1],ray_wor4d[2]);
ray_wor.normalize();

//setup ray
Ray ray = new Ray();
ray.p.set(width/2.0,height/2.0,0);
ray.dir.set(ray_wor);

return ray;
}

This is how I try to get if there is a collision with a plane and if the collision contact is in the plan :

public boolean intersectInPlane(Ray ray, PVector center , PVector nPlane, PVector halfSize){
PVector nPlaneSub = new PVector();
nPlane.sub(nPlane,ray.p,nPlaneSub);
float t = -((float)ray.p.dot(nPlaneSub))/((float)ray.dir.dot(nPlane));
if(t<=0)
return false;
println(t);
ray.dir.mult((float)t);
ray.p.add(ray.dir);
PVector centerMax = new PVector(center.x+halfSize.x,center.y+halfSize.y,center.z+halfSize.z);
PVector centerMin = new PVector(center.x-halfSize.x,center.y-halfSize.y,center.z-halfSize.z);
if(ray.p.x>=centerMin.x && ray.p.x<=centerMax.x
&& ray.p.y>=centerMin.y && ray.p.y<=centerMax.y
&& ray.p.z>=centerMin.z && ray.p.z<=centerMax.z)
return true;
return false;
}

The 't' has some really weird values and the contact is never in the plane. The models are in Z=-500 but the t is something in the line of 516753 which is a bit much.

rXp