Initial commit

shaders/findGridHash.wgsl

@@ -0,0 +1,49 @@
+@group(0) @binding(0) var<storage, read_write> positions: array<vec3<f32>>;
+
+
+@group(0) @binding(1) var<storage, read_write> gridHashes: array<u32>;
+
+@group(0) @binding(2) var<storage, read_write> indices: array<u32>;
+
+
+@group(0) @binding(3) var<uniform> cellCount: u32;
+
+@group(0) @binding(4) var<uniform> gridMin: vec3<f32>;
+
+@group(0) @binding(5) var<uniform> gridMax: vec3<f32>;
+
+fn getHash(gridCoordinate: vec3<i32>, cellCount: u32) -> u32 {
+
+let maxIndex = i32(cellCount) - 1;
+
+	let x = max(0, min(gridCoordinate.x, maxIndex));
+	let y = max(0, min(gridCoordinate.y, maxIndex));
+	let z = max(0, min(gridCoordinate.z, maxIndex));
+
+	return u32(x + y * i32(cellCount) + z * i32(cellCount) * i32(cellCount));
+}
+
+@compute @workgroup_size(256)
+fn computeMain(@builtin(global_invocation_id) globalInvocationId: vec3<u32>) {
+
+	let particleIndex = globalInvocationId.x;
+
+	if ( particleIndex >= arrayLength(&positions) ) {
+		return;
+	}
+
+	var currentPosition 	= positions[particleIndex];
+
+let cellSize = (gridMax - gridMin) / f32(cellCount);  // 2.0 / 16 = 0.125
+
+let relativePos = currentPosition - gridMin;          // currentPosition + 1
+
+let gridCoord = vec3<i32>(floor(relativePos / cellSize));  // relativePos divided by cellSize, then floored
+
+let hash = getHash(gridCoord, cellCount);
+
+	gridHashes[ particleIndex ] 	= hash;
+
+	indices[ particleIndex ] 		= particleIndex;
+
+}