Work on transparency of windows/clouds

shader/pull/window.frag

@@ -1,11 +1,14 @@
 #version 450 core
-layout (location=0) out vec4 fCol;
-layout (location=1) out vec4 fPos;
+layout (location=0) out vec4 fColOverCloud;
+layout (location=1) out vec4 fColUnderCloud;
 layout(binding = 3) uniform sampler2D cloudpos;
 in vec4 vCol;
 in vec4 vPos;
+in vec2 vScreenPos;
 void main()
 {
-  fCol = vCol;
-  fPos = vPos;
+  float cloudz = texture(cloudpos, vScreenPos).z;
+  fColOverCloud = ( cloudz > vPos.z ? vec4(0) : vCol);
+  fColUnderCloud = ( cloudz > vPos.z ? vCol : vec4(0));
+  fColUnderCloud = vec4(0);
 }

shader/pull/window.vert

@@ -4,14 +4,22 @@ layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
 layout (std430, binding = 1) readonly buffer Pos { PosCol data[]; };
 out vec4 vCol;
 out vec4 vPos;
-int indices[6] = {0,1,3,0,3,2};
+out vec2 vScreenPos;
+//int indices[6] = {0,1,3,0,3,2};
+int indices[6] = 
+    {0,3,1
+    ,0,2,3};
+// note reversed compared to walls
 void main()
 {
     vCol = data[gl_VertexID / 6].col;
     vec4 pp = data[gl_VertexID / 6].pospos;
     int j = indices[gl_VertexID % 6];
-    float z = (j > 1.5 ? 5000 : 0);
+    //float z = (j > 1.5 ? 5000 : 0);
+    float z = (j > 1.5 ? 200 : 0);
     vec2 xy = (j % 2 > 0 ? pp.xy : pp.zw);
     vPos = vec4( xy, z, 1);
     gl_Position = theMat * vPos;
+    vScreenPos = 0.5 * (vec2(1) + vec2(gl_Position.x / gl_Position.w
+                    ,gl_Position.y / gl_Position.w));
 }