Add an effect for rendering a procedurally generated sky

[libs/gl.git] / builtin_data / _sky_backdrop.glsl

diff --git a/builtin_data/_sky_backdrop.glsl b/builtin_data/_sky_backdrop.glsl
new file mode 100644 (file)
index 0000000..0aac6c8
--- /dev/null
+++ b/builtin_data/_sky_backdrop.glsl
@@ -0,0 +1,22 @@
+import msp_interface;
+import _sky;
+
+uniform sampler2D distant;
+
+#pragma MSP stage(vertex)
+void main()
+{
+       gl_Position = vec4(vertex.xy, 1.0, 1.0);
+       mat4 inv_projection = inverse(projection_matrix);
+       out vec4 view_dir = inv_projection*vec4(vertex.xy, -1.0, 1.0);
+       view_dir /= view_dir.w;
+       view_dir = inverse(eye_world_matrix)*vec4(view_dir.xyz, 0.0);
+}
+
+#pragma MSP stage(fragment)
+void main()
+{
+       vec3 nview = normalize(view_dir.xyz);
+       float azimuth = atan(nview.y, nview.x);
+       frag_color = texture(distant, vec2(azimuth/(2*pi), nview.z*0.5+0.5))*light_color;
+}