Player position in world space to screen position.

im working on making a shader that dissolve objects that are in front of players. my problem is that i dont know how to make the mask in screen space to follow the player position, since the world coordinates are not the same as screen space coordinates. what do i do? (im using Amplify shader)

 

What you need to do is transform the world space position into screen space position.


You're response to to reading that might be "yeah, I know", but it's also kind of the entire answer. Well, to be fair, I guess there are two steps this this.

Step 0: Set player's world position vector on the material using mat.SetVector() or using Shader.SetGlobalVector() via script (I assume you're already doing this).
Step 1: Get the clip space position of that position.
Step 2: Get the screen space position of that position & apply perspective divide.​

If you were writing shaders in HLSL it would look like this:

float4 playerClipPos = mul(UNITY_MATRIX_VP, float4(_PlayerPosition.xyz, 1.0));
float4 playerScreenPos = ComputeScreenPos(playerClipPos);
playerScreenPos.xy /= playerScreenPos.w;

And you're done. The UNITY_MATRIX_VP is the view projection matrix. You should be able to access that via the Common Transform Matrices node. The ComputeScreenPos function also exists as a node you can use directly, which appears to have an option to apply the perspective divide (i.e.: divide by w). I don't use Amplify so I couldn't answer the rest of how to translate that code to ASE.

I'd recommend asking if the official ASE forums rather than here.
http://amplify.pt/forum/viewforum.php?f=23

 

Hey thx for the reply. i have been fiddling around with this but dont know how translate the HLSL code to node based... ill try ask on amplify forum =)