Colour Temperature Shader

game/scripts/shaders.rpy

@@ -15,3 +15,30 @@ init python:
                 gl_FragColor = col;
         }
     """)
+
+    renpy.register_shader("color_temperature_shader", variables="""
+            uniform float u_factor;
+            uniform float u_strength;
+        """, fragment_functions="""
+            vec3 CBT(float ctemp) {
+                mat3 m = (ctemp <= 6500.0) ? mat3(vec3(0.0, -2902.1955373783176, -8257.7997278925690),
+                                                vec3(0.0, 1669.5803561666639, 2575.2827530017594),
+                                                vec3(1.0, 1.3302673723350029, 1.8993753891711275)) :
+                                                mat3(vec3(1745.0425298314172, 1216.6168361476490, -8257.7997278925690),
+                                                vec3(-2666.3474220535695, -2173.1012343082230, 2575.2827530017594),
+                                                vec3(0.55995389139931482, 0.70381203140554553, 1.8993753891711275));
+                return mix(clamp(vec3(m[0] / (vec3(clamp(ctemp, 1000.0, 40000.0)) + m[1]) + m[2]), vec3(0.0), vec3(1.0)), vec3(1.0), smoothstep(1000.0, 0.0, ctemp));
+            }
+        """, fragment_300="""
+        const float PI2 = 6.2831853071;
+
+        float ctemp = mix(1000.0, 40000.0, u_factor);
+        gl_FragColor = vec4(mix(gl_FragColor.xyz, gl_FragColor.xyz * CBT(ctemp), u_strength), 1.0);
+    """)
+
+transform color_temperature(factor=1.0, strength=1.0):
+    mesh True
+    shader "color_temperature_shader"
+
+    u_factor factor
+    u_strength strength