Add FastIntegralImage

orx-integral-image/src/main/resources/shaders/gl3/integral-image.frag

@@ -0,0 +1,26 @@
+#version 330 core
+
+uniform sampler2D tex0;
+in vec2 v_texCoord0;
+out vec4 o_color;
+
+uniform int passIndex;
+uniform int sampleCount;
+uniform int sampleCountBase;
+uniform vec2 passDirection;
+
+
+void main() {
+    vec2 passOffset = vec2(pow(sampleCountBase, passIndex)) * (1.0/textureSize(tex0, 0)) * passDirection;
+
+    vec2 uv0 = v_texCoord0;
+    vec4 result = vec4(0.0);
+    for (int i = 0; i < sampleCount; ++i) {
+        vec2 readUV = v_texCoord0 - vec2(i *passOffset);
+        float factor = step(0.0, readUV.x) * step(0.0, readUV.y);
+        result += factor * texture(tex0, readUV);
+    }
+
+    o_color = result;
+
+}