Code :
#version 150
 
uniform sampler2D TextureID;
 
smooth in vec4 theColor;
smooth in vec2 theTextureCoord;
 
out vec4 outputColor;
 
void main()
{
    vec4 value = texture2D(TextureID, theTextureCoord);
 
    if ( value.a <= 0.01 )
       discard;
 
    outputColor = value;
}

That is my Fragment Shader. As you see, I do a simple AlphaTest. Now I want to read back the final image which is rendered for doing a Collision Test on the pixels.
At least thats my idea.
How can I do that? Or is my approach wrong?