feat: Add GLSL renderer and implement FPS overlay across rendering backends

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_renderer/shaders/wolf_world.frag

@@ -0,0 +1,43 @@
+#include <flutter/runtime_effect.glsl>
+
+uniform vec2 uResolution;
+uniform vec2 uTexel;
+uniform sampler2D uTexture;
+
+out vec4 fragColor;
+
+float luma(vec3 color) {
+  return dot(color, vec3(0.299, 0.587, 0.114));
+}
+
+void main() {
+  vec2 uv = FlutterFragCoord().xy / uResolution;
+  vec4 centerSample = texture(uTexture, uv);
+
+  vec3 sampleN = texture(uTexture, uv + vec2(0.0, -uTexel.y)).rgb;
+  vec3 sampleS = texture(uTexture, uv + vec2(0.0, uTexel.y)).rgb;
+  vec3 sampleE = texture(uTexture, uv + vec2(uTexel.x, 0.0)).rgb;
+  vec3 sampleW = texture(uTexture, uv + vec2(-uTexel.x, 0.0)).rgb;
+
+  float lumaCenter = luma(centerSample.rgb);
+  float lumaMin = min(
+    lumaCenter,
+    min(min(luma(sampleN), luma(sampleS)), min(luma(sampleE), luma(sampleW)))
+  );
+  float lumaMax = max(
+    lumaCenter,
+    max(max(luma(sampleN), luma(sampleS)), max(luma(sampleE), luma(sampleW)))
+  );
+
+  float edgeSpan = max(lumaMax - lumaMin, 0.0001);
+  float edgeAmount = smoothstep(0.03, 0.18, edgeSpan);
+  vec3 neighborhoodAvg = (sampleN + sampleS + sampleE + sampleW) * 0.25;
+  vec3 aaColor = mix(centerSample.rgb, neighborhoodAvg, edgeAmount * 0.45);
+
+  vec2 centered = uv - 0.5;
+  float vignette = 1.0 - dot(centered, centered) * 0.35;
+  vignette = clamp(vignette, 0.75, 1.0);
+
+  vec3 color = aaColor * vignette;
+  fragColor = vec4(color, centerSample.a);
+}