added raymarching demo for testing

src/shaders/shader.frag

@@ -1,13 +1,28 @@
 // shader.frag
 #version 450
 
+// Variables
 layout(location=0) in vec2 vert_uv;
-layout(location=0) out vec4 frag_color;
-
+layout(location=0) out vec4 out_color;
 layout(set=0, binding=0) uniform texture2D tex;
 layout(set=0, binding=1) uniform sampler tex_smp;
 
+// Defines
+#define PI 3.141592
+#define EPSILON 0.01
+#define NEAR 0.01
+#define MAX_STEPS 200
+
+// Include
+#include "shapes.cginc"
+#include "raymarching.cginc"
+
 void main() 
 {
-    frag_color = texture(sampler2D(tex, tex_smp), vert_uv);
+    // Calculate ray
+    vec3 ro = vec3(0.0, 2, -6.0); // Ray origin
+    vec3 rd = normalize(vec3(vert_uv - vec2(0.5, 0.5), 1.001)); // Ray direction
+    
+    // Render
+    out_color = vec4(raymarch(ro, rd), 1);
 }