Implement something like deferred lighting

shader/dualTwoD/basicTweakZ.vert

@@ -2,11 +2,13 @@
 layout (location = 0) in vec4 position;
 layout (location = 1) in vec4 color;
 layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
-out vec4 vColor;
+out vec4 vCol;
+out vec3 vPos;
 void main()
 {
   vec4 posxy = theMat * vec4(position.xyz,1);
   vec4 posz  = theMat * vec4(position.xyw,1);
   gl_Position = vec4(posxy.xy,posz.z,1);
-  vColor = color;
+  vCol = color;
+  vPos = position.xyz;
 }