🚚 Move shader code to GLSL files

resources/shaders/trex-declarations.glsl

@@ -0,0 +1,57 @@
+// Inject some common shader snippets. It is only possible to include glsl files from the
+// "common" directory. Also, the files in the "common" directory are not allowed to
+// include any further files.
+#include "common/uniforms.glsl"
+#include "common/noise.glsl"
+#include "common/compositing.glsl"
+
+// See assets/README.md for how this texture was created.
+uniform sampler2D uClawTexture;
+uniform vec4 uFlashColor;
+uniform vec2 uSeed;
+uniform float uClawSize;
+uniform float uNumClaws;
+uniform float uWarpIntensity;
+
+const float FLASH_INTENSITY = 0.1;
+const float MAX_SPAWN_TIME =
+  0.6;  // Scratches will only start in the first half of the animation.
+const float FF_TIME = 0.6;  // Relative time for the final fade to transparency.
+
+// This method generates a grid of randomly rotated, slightly shifted and scaled
+// UV squares. It returns the texture coords of the UV square at the given actor
+// coordinates. If these do not fall into one of the UV grids, the coordinates of
+// the closest UV grid will be clamped and returned.
+vec2 getClawUV(vec2 texCoords, float gridScale, vec2 seed) {
+
+  // Shift coordinates by a random offset and make sure the have a 1:1 aspect ratio.
+  vec2 coords = texCoords + hash22(seed);
+  coords *= uSize.x < uSize.y ? vec2(1.0, 1.0 * uSize.y / uSize.x)
+                              : vec2(1.0 * uSize.x / uSize.y, 1.0);
+
+  // Apply global scale.
+  coords *= gridScale;
+
+  // Get grid cell coordinates in [0..1].
+  vec2 cellUV = mod(coords, vec2(1));
+
+  // This is unique for each cell.
+  vec2 cellID = coords - cellUV + vec2(362.456);
+
+  // Add random rotation, scale and offset to each grid cell.
+  float scale    = mix(0.8, 1.0, hash12(cellID * seed * 134.451));
+  float offsetX  = mix(0.0, 1.0 - scale, hash12(cellID * seed * 54.4129));
+  float offsetY  = mix(0.0, 1.0 - scale, hash12(cellID * seed * 25.3089));
+  float rotation = mix(0.0, 2.0 * 3.141, hash12(cellID * seed * 2.99837));
+
+  cellUV -= vec2(offsetX, offsetY);
+  cellUV /= scale;
+
+  cellUV -= 0.5;
+  cellUV = vec2(cellUV.x * cos(rotation) - cellUV.y * sin(rotation),
+                cellUV.x * sin(rotation) + cellUV.y * cos(rotation));
+  cellUV += 0.5;
+
+  // Clamp resulting coordinates.
+  return clamp(cellUV, vec2(0), vec2(1));
+}