1 files changed, 95 insertions, 2 deletions
diff --git a/src/shaders/main.glsl b/src/shaders/main.glsl
index 4e2d4ea..784176f 100644
--- a/src/shaders/main.glsl
+++ b/src/shaders/main.glsl
@@ -11,22 +11,115 @@ layout(binding=0) uniform vs_params {
 };
 
 in vec2 vpos;
+out vec2 fpos;
 
 void main() {
     gl_Position = vec4(vpos + position, 0, 1);
+    fpos = (vpos + 1) * 0.5;
 }
 @end
 
 @fs fs_offscreen
+layout(binding=1) uniform texture2D off_tex;
+layout(binding=1) uniform sampler off_smp;
 layout(binding=1) uniform fs_params {
-    vec4 color;
+    vec2 resolution;
+    int rayCount;
+    int maxSteps;
+    float size;
 };
 
+in vec2 fpos;
 out vec4 frag_color;
 
+bool outOfBounds(vec2 uv) {
+    return uv.x < 0.0 || uv.x > 1.0 || uv.y < 0.0 || uv.y > 1.0;
+}
+
+#define TAU 6.28318530718
+// #define RAYCOUNT 16
+// #define MAXSTEPS 8
+
+float rand(vec2 seed)
+{
+    return fract(sin(dot(seed.xy, vec2(12.9898, 78.233))) * 43758.5453);
+}
+
+vec4 raymarch() {
+    vec2 scale = resolution.xy / resolution.xy;
+
+    // sample texture at pixel
+    vec4 light = textureLod(sampler2D(off_tex, off_smp), fpos * scale, 0);
+    // if it is a light source, color that pixel in this color
+    if (light.a > 0.1)
+    {
+        return light;
+    }
+
+    float oneOverRayCount = 1.0 / float(rayCount);
+    float tauOverRayCount = TAU * oneOverRayCount;
+
+    float noise = rand(fpos);
+
+    vec4 radiance = vec4(0.0);
+
+    for (int i = 0; i < rayCount; i++)
+    {
+        float angle = tauOverRayCount * (float(i) + noise);
+        vec2 rayDirectionUv = vec2(cos(angle), -sin(angle)) / size;
+
+        vec2 sampleUv = fpos + rayDirectionUv;
+
+        for (int step = 0; step < maxSteps; step++)
+        {
+            if (outOfBounds(sampleUv))
+                break;
+
+            vec4 sampleLight = textureLod(sampler2D(off_tex, off_smp), sampleUv, 0);
+            if (sampleLight.a > 0.1)
+            {
+                radiance += sampleLight;
+                break;
+            }
+
+            sampleUv += rayDirectionUv;
+        }
+    }
+
+    return radiance * oneOverRayCount;
+}
+
 void main() {
-    frag_color = color;
+    frag_color = raymarch();
 }
 @end
 
 @program offscreen vs_offscreen fs_offscreen
+
+
+// default-pass shaders
+@vs vs_default
+
+in vec2 vpos;
+out vec2 fpos;
+
+void main() {
+    gl_Position = vec4(vpos, 0, 1);
+    fpos = (vpos + 1) * 0.5;
+}
+@end
+
+@fs fs_default
+layout(binding=0) uniform texture2D scr_tex;
+layout(binding=0) uniform sampler scr_smp;
+
+in vec2 fpos;
+
+out vec4 frag_color;
+
+void main() {
+    frag_color = texture(sampler2D(scr_tex, scr_smp), fpos);
+}
+@end
+
+@program default vs_default fs_default