Simple vertex shader for dome rendering.

data/dome.vs

+#version 110
+
+// uniform parameters
+float zoom = 1.0;
+float tilt = 45.0;
+
+
+const float pi_2 = 1.5707963267949;
+
+float Pzz = gl_ProjectionMatrix[2][2]; 
+float Pwz = gl_ProjectionMatrix[3][2]; 
+float nearclip = Pwz / (Pzz - 1.0);
+
+float aspect = gl_ProjectionMatrix[0][0] / gl_ProjectionMatrix[1][1];
+float xstretch = (aspect < 1.0) ? aspect : 1.0;
+float ystretch = (aspect > 1.0) ? 1.0/aspect : 1.0;
+
+float stilt = sin(radians(tilt));
+float ctilt = cos(radians(tilt));
+
+void main() {
+   vec4 p = gl_ModelViewMatrix * gl_Vertex;
+   float yt = p.y*ctilt - p.z*stilt;
+   float zt = p.z*ctilt + p.y*stilt;
+
+   float r = sqrt(p.x*p.x + yt*yt);
+   float arc = atan( r / zt );
+   float w = (zt < -nearclip && abs(arc) < pi_2) ? pi_2*zoom : -pi_2*zoom;
+   float arc_r = arc / r;
+   gl_Position = vec4( xstretch * p.x * arc_r, ystretch * yt * arc_r, 0.5, w );
+   gl_FrontColor = gl_Color;
+   gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
+}