[orx-fx] Add fisheye distortion to Lenses Filter

orx-fx/src/commonMain/kotlin/distort/Lenses.kt

@@ -9,15 +9,15 @@ import org.openrndr.extra.fx.mppFilterShader
 import org.openrndr.extra.parameters.BooleanParameter
 import org.openrndr.extra.parameters.Description
 import org.openrndr.extra.parameters.DoubleParameter
+import org.openrndr.extra.parameters.IntParameter
 
 @Description("Lenses")
 class Lenses : Filter(mppFilterShader(fx_lenses, "block-repeat")) {
-    @DoubleParameter("block width", 0.0, 1.0, order = 0)
+    @IntParameter("rows", 1, 64, order = 0)
-    var blockWidth: Double by parameters
+    var rows: Int by parameters
-
-    @DoubleParameter("block height", 0.0, 1.0, order = 1)
-    var blockHeight: Double by parameters
 
+    @IntParameter("columns", 1, 64, order = 1)
+    var columns: Int by parameters
 
     @DoubleParameter("scale", 0.5, 1.5, order = 2)
     var scale: Double by parameters
@@ -25,6 +25,9 @@ class Lenses : Filter(mppFilterShader(fx_lenses, "block-repeat")) {
     @DoubleParameter("rotation", -180.0, 180.0, order = 3)
     var rotation: Double by parameters
 
+    @DoubleParameter("distort", -1.0, 1.0, order = 4)
+    var distort: Double by parameters
+
     @BooleanParameter("bicubic filtering")
     var bicubicFiltering: Boolean by parameters
 
@@ -37,8 +40,9 @@ class Lenses : Filter(mppFilterShader(fx_lenses, "block-repeat")) {
     }
 
     init {
-        blockWidth = 0.25
+        rows = 6
-        blockHeight = 0.25
+        columns = 8
+        distort = 0.0
 
         bicubicFiltering = true
     }

orx-fx/src/demo/kotlin/DemoDistortLenses01.kt

@@ -2,7 +2,6 @@ import org.openrndr.application
 import org.openrndr.draw.createEquivalent
 import org.openrndr.draw.loadImage
 import org.openrndr.extra.fx.distort.Lenses
-import kotlin.math.cos
 
 fun main() = application {
     configure {
@@ -16,7 +15,8 @@ fun main() = application {
         val edges = image.createEquivalent()
         extend {
             lenses.rotation = 0.0
-            lenses.scale = 1.4
+            lenses.scale = 1.5
+
             lenses.apply(image, edges)
             drawer.image(edges)
         }

orx-fx/src/shaders/glsl/distort/lenses.frag

@@ -2,25 +2,29 @@ in vec2 v_texCoord0;
 uniform sampler2D tex0;// input
 uniform float scale;
 uniform float rotation;
+uniform int rows;
+uniform int columns;
+uniform float distort;
 
 out vec4 o_color;
 void main() {
     vec2 uv = v_texCoord0;
-    vec2 blockSize = vec2(1.0/8.0, 1.0/6.0);
+    vec2 blockSize = vec2(1.0/columns, 1.0/rows);
-
     vec2 blockIndex = floor(uv / blockSize);
+    vec2 blockUV = mod(uv/blockSize, vec2(1.0));
+    vec2 blockUVC1 = (blockUV - vec2(0.5)) * 2.0;
     vec2 blockCenter = (blockIndex+0.5) * blockSize;
 
     float ca = cos(radians(rotation));
     float sa = sin(radians(rotation));
 
     vec2 ts = textureSize(tex0, 0);
-
     mat2 rm = mat2(1.0, 0.0, 0.0, ts.x/ts.y) * mat2(vec2(ca, sa), vec2(-sa, ca)) * mat2(1.0, 0.0, 0.0, ts.y/ts.x);
-    vec2 cuv = (rm * (uv - blockCenter)
+    vec2 ruv = (uv - blockCenter);
-    * scale + blockCenter);
+    vec2 luv;
-
+    luv.x = (1.0 - blockUVC1.y * blockUVC1.y * distort) * ruv.x;
-
+    luv.y = (1.0 - blockUVC1.x * blockUVC1.x * distort) * ruv.y;
+    vec2 cuv = (rm * luv * scale + blockCenter);
 
     float sx = step(0.0, cuv.x) * (1.0 - step(1.0, cuv.x));
     float sy = step(0.0, cuv.y) * (1.0 - step(1.0, cuv.y));