From b54c44c6b83ca2490e56ba9b449bdae2d057bd32 Mon Sep 17 00:00:00 2001
From: itsmattkc <itsmattkc@gmail.com>
Date: Sun, 11 Nov 2018 22:06:30 +1100
Subject: [PATCH] added swirl effect

---
 effects/effects/swirl.frag | 33 +++++++++++++++++++++++++++++++++
 effects/effects/swirl.xml  | 14 ++++++++++++++
 2 files changed, 47 insertions(+)
 create mode 100644 effects/effects/swirl.frag
 create mode 100644 effects/effects/swirl.xml

diff --git a/effects/effects/swirl.frag b/effects/effects/swirl.frag
new file mode 100644
index 000000000..3c093211e
--- /dev/null
+++ b/effects/effects/swirl.frag
@@ -0,0 +1,33 @@
+#version 110
+
+// Swirl effect parameters
+uniform float radius;
+uniform float angle;
+uniform float center_x;
+uniform float center_y;
+uniform vec2 resolution;
+
+uniform sampler2D myTexture;
+varying vec2 vTexCoord;
+
+void main(void) {
+	vec2 center = vec2(center_x, center_y);
+
+	vec2 uv = vTexCoord.st;
+
+	vec2 tc = uv * resolution;
+	tc -= center;
+	float dist = length(tc);
+	if (dist < radius) {
+		float percent = (radius - dist) / radius;
+		float theta = percent * percent * (-angle*0.05) * 8.0;
+		float s = sin(theta);
+		float c = cos(theta);
+		tc = vec2(dot(tc, vec2(c, -s)), dot(tc, vec2(s, c)));
+	}
+	tc += center;
+	vec3 color = texture2D(myTexture, tc / resolution).rgb;
+	gl_FragColor = vec4(color, 1.0);
+
+
+}
\ No newline at end of file
diff --git a/effects/effects/swirl.xml b/effects/effects/swirl.xml
new file mode 100644
index 000000000..962018379
--- /dev/null
+++ b/effects/effects/swirl.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<effect name="Swirl" category="Distort">
+	<row name="Radius">
+		<field type="double" min="0" default="10" id="radius"/>
+	</row>
+	<row name="Angle">
+		<field type="double" default="10" id="angle"/>
+	</row>
+	<row name="Center">
+		<field type="double" default="0" id="center_x"/>
+		<field type="double" default="0" id="center_y"/>
+	</row>
+	<shader vert="common.vert" frag="swirl.frag"/>
+</effect>
\ No newline at end of file