playcanvas/build/playcanvas.prf/src/scene/shader-lib/glsl/chunks/gsplat/frag/gsplatIntervalTexture.js

PlayCanvas WebGL game engine

var gsplatIntervalTextureGLSL = `
precision highp usampler2D;
uniform usampler2D uIntervalsTexture;
uniform int uNumIntervals;
uniform int uTextureWidth;
uniform int uActiveSplats;
ivec2 getCoordFromIndex(int index, int textureWidth) {
	return ivec2(index % textureWidth, index / textureWidth);
}
void main() {
	ivec2 coord = ivec2(gl_FragCoord.xy);
	int targetIndex = coord.y * uTextureWidth + coord.x;
	
	if (targetIndex >= uActiveSplats) {
		gl_FragColor = 0u;
		return;
	}
	
	int left = 0;
	int right = uNumIntervals - 1;
	int intervalIndex = 0;
	
	while (left <= right) {
		int mid = (left + right) / 2;
		
		int textureWidth = textureSize(uIntervalsTexture, 0).x;
		ivec2 intervalCoord = getCoordFromIndex(mid, textureWidth);
		uvec2 intervalData = texelFetch(uIntervalsTexture, intervalCoord, 0).rg;
		
		uint accumulatedSum = intervalData.g;
		
		if (uint(targetIndex) < accumulatedSum) {
			intervalIndex = mid;
			right = mid - 1;
		} else {
			left = mid + 1;
		}
	}
	
	int textureWidth = textureSize(uIntervalsTexture, 0).x;
	ivec2 intervalCoord = getCoordFromIndex(intervalIndex, textureWidth);
	uvec2 intervalData = texelFetch(uIntervalsTexture, intervalCoord, 0).rg;
	
	uint intervalStart = intervalData.r;
	uint currentAccSum = intervalData.g;
	
	uint prevAccSum = 0u;
	if (intervalIndex > 0) {
		ivec2 prevCoord = getCoordFromIndex(intervalIndex - 1, textureWidth);
		prevAccSum = texelFetch(uIntervalsTexture, prevCoord, 0).g;
	}
	
	uint offsetInInterval = uint(targetIndex) - prevAccSum;
	uint originalIndex = intervalStart + offsetInInterval;
	
	gl_FragColor = originalIndex;
}
`;

export { gsplatIntervalTextureGLSL as default };