fixing shader execution

example/shader.nzsl

@@ -16,16 +16,16 @@ struct FragOut
 [entry(frag)]
 fn main(input: FragIn) -> FragOut
 {
-    const I: i32 = 32;
+    const I: i32 = 128;
     const A: f32 = 7.5;
-    const MA: f32 = 20.0;
+    const MA: f32 = 100.0;
     const MI: f32 = 0.001;
 
     let uv0 = input.pos / input.res * 2.0 - vec2[f32](1.0, 1.0);
     let uv  = vec2[f32](uv0.x * (input.res.x / input.res.y), uv0.y);
 
-    let col = vec3[f32](0.0, 0.0, 0.0);
-    let ro  = vec3[f32](0.0, 0.0, -2.0);
+    let col = vec3[f32](0.0, 0.0, 0.0);  
+    let ro  = vec3[f32](0.0, 0.0, -2.0); 
     let rd  = vec3[f32](uv.x, uv.y, 1.0);
     let dt  = 0.0;
     let ds  = 0.0;