shaderexp: add initial shader explorer tool (#245)

* shaderexp: first commit
* shaderexp: further improve error handling
* shaderexp: attribute ray_marching example

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
Co-authored-by: Stephen Gutekanst <stephen@hexops.com>

shaderexp/example-shaders/mandelbrot.wgsl

@@ -0,0 +1,38 @@
+struct UniformBufferObject {
+    resolution: vec2<f32>,
+    time: f32,
+}
+@group(0) @binding(0) var<uniform> ubo : UniformBufferObject;
+
+@stage(fragment) fn main(
+    @location(0) uv : vec2<f32>
+) -> @location(0) vec4<f32> {
+    let aspect = ubo.resolution / min(ubo.resolution.x,ubo.resolution.y);
+    let translated_uv = (uv - vec2(0.5,0.5)) * aspect * 2.0;
+    let col = f32(mandel(translated_uv)) / 100.0;
+
+    return vec4(vec3<f32>(col), 1.0);
+}
+
+fn mandel(uv: vec2<f32>) -> i32{
+    let zoom = 1.0;
+    let center_position = vec2<f32>(0.5,0.0);
+    let mapped_point = uv * zoom - center_position;
+    var z = mapped_point;
+    var tmp:f32;
+    var i:i32 = 0;
+    var found = false;
+    var res = 0;
+    loop {
+        if (i >= 100){
+            break;
+        }
+        tmp = z.x;
+        z.x = z.x * z.x - z.y * z.y + mapped_point.x;
+        z.y = 2. * tmp * z.y + mapped_point.y;
+        found = found || (z.x * z.x + z.y * z.y > 16.);
+        res = res + 1 * i32(!found);
+        i = i + 1;
+    }
+    return res;
+}