1 files changed, 41 insertions, 0 deletions
diff --git a/examples/shaders/shaders_palette_switch.data b/examples/shaders/shaders_palette_switch.data
new file mode 100644
index 0000000..e5b038d
--- /dev/null
+++ b/examples/shaders/shaders_palette_switch.data
@@ -0,0 +1,41 @@
+#version 100
+
+precision mediump float;
+
+const int colors = 8;
+
+// Input vertex attributes (from vertex shader)
+varying vec2 fragTexCoord;
+varying vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform ivec3 palette[colors];
+
+void main()
+{
+    // Texel color fetching from texture sampler
+    vec4 texelColor = texture2D(texture0, fragTexCoord)*fragColor;
+
+    // Convert the (normalized) texel color RED component (GB would work, too)
+    // to the palette index by scaling up from [0, 1] to [0, 255].
+    int index = int(texelColor.r*255.0);
+    
+    ivec3 color = ivec3(0);
+    
+    // NOTE: On GLSL 100 we are not allowed to index a uniform array by a variable value,
+    // a constantmust be used, so this logic...
+    if (index == 0) color = palette[0];
+    else if (index == 1) color = palette[1];
+    else if (index == 2) color = palette[2];
+    else if (index == 3) color = palette[3];
+    else if (index == 4) color = palette[4];
+    else if (index == 5) color = palette[5];
+    else if (index == 6) color = palette[6];
+    else if (index == 7) color = palette[7];
+
+    // Calculate final fragment color. Note that the palette color components
+    // are defined in the range [0, 255] and need to be normalized to [0, 1]
+    // for OpenGL to work.
+    gl_FragColor = vec4(float(color.x)/255.0, float(color.y)/255.0, float(color.z)/255.0, texelColor.a);
+}