From aca017dec15306715b11341c2ae05f0be1690b1c Mon Sep 17 00:00:00 2001
From: hellerve <veit@veitheller.de>
Date: Tue, 6 Jun 2017 01:30:01 -0400
Subject: [PATCH] basic: added color panes and moving lights; utilities: added
 shapes; weird: added piet (doesnt scale)

---
 basic/color_panes.glsl   | 12 ++++++++++++
 basic/moving_lights.glsl | 14 ++++++++++++++
 utilities/shapes.glsl    |  6 ++++++
 weird/piet.glsl          | 39 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 71 insertions(+)
 create mode 100644 basic/color_panes.glsl
 create mode 100644 basic/moving_lights.glsl
 create mode 100644 utilities/shapes.glsl
 create mode 100644 weird/piet.glsl

diff --git a/basic/color_panes.glsl b/basic/color_panes.glsl
new file mode 100644
index 0000000..508d2ae
--- /dev/null
+++ b/basic/color_panes.glsl
@@ -0,0 +1,12 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+
+void main(){
+    vec2 st = gl_FragCoord.xy/u_resolution.xy;
+
+    gl_FragColor = vec4(floor(vec3(st, u_mouse.x/u_resolution.x)+0.5),1.0);
+}
diff --git a/basic/moving_lights.glsl b/basic/moving_lights.glsl
new file mode 100644
index 0000000..96c7243
--- /dev/null
+++ b/basic/moving_lights.glsl
@@ -0,0 +1,14 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+void main(){
+    vec2 p1 = vec2(0.8*abs(sin(u_time)), 0.8*abs(cos(u_time)));
+    vec2 p2 = u_mouse/u_resolution;
+    vec2 st = gl_FragCoord.xy/u_resolution;
+    gl_FragColor = vec4(vec3(pow(distance(st,vec2(p1))*0.5,distance(st,p2)*0.5)), 1.0);
+}
diff --git a/utilities/shapes.glsl b/utilities/shapes.glsl
new file mode 100644
index 0000000..039c132
--- /dev/null
+++ b/utilities/shapes.glsl
@@ -0,0 +1,6 @@
+vec3 circle(in vec2 _st, in float _radius, vec3 color){
+    vec2 dist = _st-vec2(0.5);
+    return color-smoothstep(_radius-(_radius*0.02),
+                         _radius+(_radius*0.02),
+                         dot(dist,dist)*4.0);
+}
diff --git a/weird/piet.glsl b/weird/piet.glsl
new file mode 100644
index 0000000..16bf51d
--- /dev/null
+++ b/weird/piet.glsl
@@ -0,0 +1,39 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+vec3 WHITE  = vec3(1.);
+vec3 RED    = vec3(1.,0.,0.);
+vec3 BLACK  = vec3(0.);
+vec3 YELLOW = vec3(1.,1.,0);
+vec3 BLUE   = vec3(0.,0.,1.);
+
+// hacky but worky
+vec3 rect(float thickness, vec2 offset, vec2 size, vec3 border_color, vec3 bg_color) {
+    vec2 pos = gl_FragCoord.xy;
+    if (pos.x < offset.x || pos.y < offset.y || pos.x>size.x+thickness+offset.x || pos.y>size.y+thickness+offset.y) return WHITE;
+    bool in_left = pos.x >= offset.x && pos.x <= offset.x+thickness;
+    bool in_right = pos.x >= offset.x+size.x && pos.x <= offset.x+thickness+size.x;
+    bool in_bottom = pos.y >= offset.y && pos.y <= offset.y+thickness;
+    bool in_top = pos.y >= offset.y+size.y && pos.y <= offset.y+thickness+size.y;
+    if (in_left || in_right || in_bottom || in_top) return border_color;
+    return bg_color;
+}
+
+vec3 piet_rect(vec2 offset, vec2 size, vec3 bg_color) {
+    return rect(5., offset, vec2(size), BLACK, bg_color);
+}
+
+void main() {
+    vec3 rect1 = piet_rect(vec2(10., 210.), vec2(200.), RED);
+    vec3 rect2 = piet_rect(vec2(10.), vec2(200.), WHITE);
+    vec3 rect3 = piet_rect(vec2(-90., -5), vec2(100., 200.), BLUE);
+    vec3 rect4 = piet_rect(vec2(-10., 210), vec2(20., 20.), WHITE);
+    vec3 rect5 = piet_rect(vec2(210, -5.), vec2(50., 300), YELLOW);
+
+    gl_FragColor = vec4(rect1*rect2*rect3*rect4*rect5,1.0);
+}