Add Fisheye filter

orx-fx/src/main/kotlin/distort/Fisheye.kt

@@ -0,0 +1,40 @@
+package org.openrndr.extra.fx.distort
+
+import org.openrndr.draw.*
+import org.openrndr.extra.fx.filterFragmentCode
+import org.openrndr.extra.parameters.Description
+import org.openrndr.extra.parameters.DoubleParameter
+
+@Description("Fisheye")
+class Fisheye : Filter(Shader.createFromCode(filterVertexCode, filterFragmentCode("distort/fisheye.frag"))) {
+    @DoubleParameter("strength", -1.0, 1.0, order = 0)
+    var strength: Double by parameters
+
+    @DoubleParameter("scale", 0.0, 2.0, order = 0)
+    var scale: Double by parameters
+
+
+    @DoubleParameter("feather", 0.0, 100.0, order = 1)
+    var feather: Double by parameters
+
+    @DoubleParameter("rotation", -180.0, 180.0, order = 1)
+    var rotation : Double by parameters
+
+
+    init {
+        strength = 0.1
+        feather = 1.0
+        scale = 1.0
+        rotation = 0.0
+    }
+
+    var bicubicFiltering = true
+    override fun apply(source: Array<ColorBuffer>, target: Array<ColorBuffer>) {
+        if (bicubicFiltering && source.isNotEmpty()) {
+            source[0].generateMipmaps()
+            source[0].filter(MinifyingFilter.LINEAR_MIPMAP_LINEAR, MagnifyingFilter.LINEAR)
+        }
+        super.apply(source, target)
+
+    }
+}

orx-fx/src/main/resources/org/openrndr/extra/fx/gl3/distort/fisheye.frag

@@ -0,0 +1,44 @@
+#version 330 core
+uniform sampler2D tex0;
+uniform float strength;
+uniform float feather;
+uniform float scale;
+uniform float rotation;
+in vec2 v_texCoord0;
+out vec4 o_color;
+
+void main() {
+    vec2 uv = v_texCoord0;
+    vec2 ts = textureSize(tex0, 0);
+    vec2 step = 1.0 / ts;
+
+    float phi = radians(rotation);
+    float cp = cos(phi);
+    float sp = sin(phi);
+    mat2 rm = mat2(vec2(cp,sp), vec2(-sp,cp));
+
+
+    float aspectRatio = ts.y / ts.x;
+    step.y /= aspectRatio;
+    step *= feather;
+
+    vec2 intensity = vec2(strength,
+    strength);
+
+    vec2 coords = uv;
+    coords = (coords - 0.5) * 2.0;
+
+    coords = rm * coords;
+
+    vec2 realCoordOffs;
+    realCoordOffs.x = (1.0 - coords.y * coords.y) * intensity.y * (coords.x);
+    realCoordOffs.y = (1.0 - coords.x * coords.x) * intensity.x * (coords.y);
+
+    vec2 fuv = ((uv - realCoordOffs) - vec2(0.5)) * scale + vec2(0.5);
+
+    float fx = smoothstep(0.0, step.x, fuv.x) * smoothstep(1.0, 1.0 - step.x, fuv.x);
+    float fy = smoothstep(0.0, step.y, fuv.y) * smoothstep(1.0, 1.0 - step.y, fuv.y);
+
+    vec4 color = texture(tex0, fuv) * fx * fy;
+    o_color = color;
+}