Add glslwrite tool and some examples

1 files changed, 41 insertions, 0 deletions

diff --git a/examples/snail.frag b/examples/snail.frag
new file mode 100644
index 0000000..491c53a
--- /dev/null
+++ b/examples/snail.frag
@@ -0,0 +1,41 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 300;
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float circle(vec2 m, float r, vec2 p) {
+        vec2 diff = m - p;
+        float d = sqrt(dot(diff, diff));
+
+        return clamp((r - d)*sharpness, 0.0, 1.0);
+}
+
+float circle_d(vec2 m, float r, vec2 p) {
+        return circle(m, r, p) - circle(m, r - 1/sharpness, 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;
+
+        for (int i = 1; i <= 50; i++) {
+                float c = circle_d(vec2(0.5, 0) * rot(time/500/i), 0.1 + 0.005*i, p);
+                scene = abs(scene - c);
+        }
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}