# Calculation behind camera.WorldToScreenPoint

Hello all,

Is there any way to map world point to screen point using matrix, which output value same as one get when using Camera.main.WorldToScreenPoint function?

Unfortunately, this is mathematically impossible. One of the operations involved in computing the screen point of a world coordinate (dehomogenizing a homogeneous coordinate) cannot be represented as a linear transformation, so there cannot exist a matrix (which is really just a convenient encoding of a linear map) that can represent it.

If youâ€™re curious how the function actually works, it probably looks something like this:

``````Vector3 manualWorldToScreenPoint(Vector3 wp) {
// calculate view-projection matrix
Matrix4x4 mat = cam.projectionMatrix * cam.worldToCameraMatrix;

// multiply world point by VP matrix
Vector4 temp = mat * new Vector4(wp.x, wp.y, wp.z, 1f);

if (temp.w == 0f) {
// point is exactly on camera focus point, screen point is undefined
// unity handles this by returning 0,0,0
return Vector3.zero;
} else {
// convert x and y from clip space to window coordinates
temp.x = (temp.x/temp.w + 1f)*.5f * cam.pixelWidth;
temp.y = (temp.y/temp.w + 1f)*.5f * cam.pixelHeight;
return new Vector3(temp.x, temp.y, wp.z);
}
}
``````

I can confirm JanSenseVRâ€™s code works, thank you so much I have been searching for this for so LONG !!! @JanSenseVR