From 9d3cdc7f5ee96c3b2a9342e44b62102f5b05be3b Mon Sep 17 00:00:00 2001 From: Matthias Schiffer Date: Mon, 1 Feb 2016 14:03:21 +0100 Subject: Add glslwrite tool and some examples --- examples/polygon.frag | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 examples/polygon.frag (limited to 'examples/polygon.frag') diff --git a/examples/polygon.frag b/examples/polygon.frag new file mode 100644 index 0000000..20d5cdc --- /dev/null +++ b/examples/polygon.frag @@ -0,0 +1,54 @@ +#version 330 + +out vec4 fragColor; + +uniform vec2 res; +uniform float time; + +const float sharpness = 300; + +const float PI = 3.14159265358979323846; + + +mat2 rot(float a) { + return mat2( + cos(a), -sin(a), + sin(a), cos(a) + ); +} + +float poly(float n, vec2 m, float r, float rt, vec2 p) { + vec2 diff = (m - p) * rot(rt); + float d = length(diff); + float alpha = PI / n; + float gamma = mod(abs(atan(diff.x, diff.y)), alpha*2); + + if (gamma > alpha) + gamma -= 2*alpha; + + float r2 = r * cos(alpha) / cos(gamma); + + return clamp((r2 - d)*sharpness, 0.0, 1.0); +} + +float poly_d(float n, vec2 m, float r, float rt, vec2 p) { + return poly(n, m, r, rt, p) - poly(n, m, r - 1/sharpness, rt, p); +} + +void main(void) { + vec2 m = res/2; + float s = min(m.x, m.y); + vec2 p = (gl_FragCoord.xy - m) / s; + + float scene = 0; + + float c; + + c = poly_d(5 - 3*cos(time/1000), vec2(0, 0), 0.5, PI * time/1000, p); + scene = abs(scene - c); + + c = poly_d(5 - 3*cos(time/1000), vec2(0, 0), 0.5, -PI * time/1000, p); + scene = abs(scene - c); + + fragColor = vec4(vec3(1, 1, 1) * scene, 1); +} -- cgit v1.2.3