basic checkerboard shader

shader-test/source/PlayState.kiss

@@ -14,14 +14,18 @@
         (bg.setGraphicSize FlxG.width FlxG.height)
         (bg.screenCenter)
         (add bg))
-    (set shader (new CShader))
+    (set shader (new kiss_flixel.shaders.CheckerBoard))
-    (set shader.data.invert.value [true])
+    // (set shader.data.invert.value [true])
+    (set shader.data.color1.value [1.0 1.0 1.0 1.0])
+    (set shader.data.color2.value [0.0 0.0 0.0 1.0])
+    (set shader.data.checkSize.value [64.0])
     (let [:BitmapFilter filter (new ShaderFilter shader)
             :Array<BitmapFilter> filters [filter]]
         (FlxG.camera.setFilters filters)))
 
 (method &override :Void update [:Float elapsed]
     (super.update elapsed)
+    (+= FlxG.camera.scroll.x 1)
 
     (when FlxG.keys.justPressed.SPACE
         (set shader.data.invert.value [!(first shader.data.invert.value)])))

src/kiss_flixel/shaders/CheckerBoard.frag

@@ -0,0 +1,20 @@
+#pragma header
+
+uniform vec4 color1 = vec4(1.0, 1.0, 1.0, 1.0);
+uniform vec4 color2 = vec4(0.0, 0.0, 0.0, 1.0);
+uniform float checkSize = 64;
+
+void main()
+{
+    vec2 position = openfl_TextureCoordv * iResolution;
+    float row = floor(position.y / checkSize);
+    float col = floor(position.x / checkSize);
+
+    bool oddRow = mod(row, 2) == 1;
+    bool oddCol = mod(col, 2) == 1;
+
+    vec4 oddColor = oddRow ? color1 : color2;
+    vec4 evenColor = oddRow ? color2 : color1;
+
+    gl_FragColor = oddCol ? oddColor: evenColor;
+}