Plane's UV always facing camera

Questions
1

Hi guys, I am actually trying to achieve the next feature: I got a plane on my scene with a custom shader, I apply to the shader a 2D texture , I would want to have the texture facing the camera when I move the camera, but not to have the plane geometry moving, like a billboard but only for the texture.
I actually struggle to figure out the abstraction, understand that i need to get the camera’s position, and plane position, but dont understand how to create the “rotation” effect, if somebody can help, it will be appreciated.
Thanks a lot!

2

Maybe you mean using plane’s vertexes like uv coordinates.

2 Likes
3

instead of uv you can use FragCoord.xy / screen width or similar if you want the mesh to appear as a portal onto a texture.

4

For fragment shader need to send screen size attributes:
Javascript:

mat["screen"]=new THREE.ShaderMaterial({
uniforms:{
screenSize:{value:[screen.width,screen.height]},

Fragment Shader:

uniform vec2 screenSize;
void(){
vec4 diffuse=texture2D(map,gl_FragCoord.xy/screenSize)
};

If without screenSize uniform:

Vertex shader:

varying vec3 v2D;
void main(){
v2D=gl_Position.xyw;
}

Fragment shader:

varying vec3 v2D;
void main(){
vec4 diffuse=texture2D(map,(v2D.xy/v2D.z+1.0)*0.5);
}