Fix wall normals

shader/wall/texture.frag

@@ -4,11 +4,12 @@ layout (location=1) out vec4 fPos;
 layout (location=2) out vec4 fNorm;
 in vec2 tPos;
 in vec4 gPos;
+in vec4 gNorm;
 in vec4 gColor;
 uniform sampler2D tex;
 void main()
 {
   fCol = gColor * texture(tex,tPos);
   fPos = gPos;
-  fNorm = gPos + vec4(1,0,0,0);
+  fNorm = gNorm;
 }

shader/wall/texture.geom

@@ -6,6 +6,7 @@ in vec4 vColor [];
 out vec4 gColor;
 out vec2 tPos;
 out vec4 gPos;
+out vec4 gNorm;
 // consider using isLHS to check if the wall is facing the center
 float isLHS (vec2 startV, vec2 testV)
 { return sign( -startV.x * testV.y + startV.y * testV.x); }
@@ -15,9 +16,15 @@ void main()
   vec4 p2 = vec4 (gl_in[0].gl_Position.zw,0,1);
   vec4 p3 = vec4 (p1.xy,100,1);
   vec4 p4 = vec4 (p2.xy,100,1);
+  vec2 d = vec2(p1.xy - p2.xy);
+  vec4 norm = vec4( d.y, -d.x, 0, 1);
+  gNorm = p1 - norm;
   gPos = p1; tPos = vec2 ( 1,-1) ; gl_Position = vec4(theMat * p1); EmitVertex();
+  gNorm = p1 - norm;
   gPos = p3; tPos = vec2 ( 1, 1) ; gl_Position = vec4(theMat * p3); EmitVertex();
+  gNorm = p1 - norm;
   gPos = p2; tPos = vec2 (-1,-1) ; gl_Position = vec4(theMat * p2); EmitVertex();
+  gNorm = p1 - norm;
   gPos = p4; tPos = vec2 (-1, 1) ; gl_Position = vec4(theMat * p4); EmitVertex();
   EndPrimitive();
 }