import { AdditiveBlending, DataTexture, ShaderMaterial } from "three";
export default function createDensityAccumulatorMaterial(
nodePositionsTexture: DataTexture,
initialCameraDistance: number
) {
const densityCloudMaterial = new ShaderMaterial({
depthWrite: false,
depthTest: false,
transparent: true,
blending: AdditiveBlending,
uniforms: {
nodePositionsTexture: {
value: nodePositionsTexture,
},
textureSize: {
value: nodePositionsTexture.image.width,
},
camDist: {
value: initialCameraDistance,
},
radius: { value: 0.05 },
},
vertexShader: `
uniform sampler2D nodePositionsTexture;
uniform float textureSize;
uniform float camDist;
attribute vec3 nodeColor;
varying vec3 vColor;
varying vec2 vUv;
varying float nodeSize;
vec3 getNodePos(float idx) {
float fx = mod(idx, textureSize);
float fy = floor(idx / textureSize);
vec2 uv = (vec2(fx, fy) + 0.5) / textureSize;
return texture2D(nodePositionsTexture, uv).xyz;
}
void main() {
vUv = uv;
vColor = nodeColor;
vec3 nodePos = getNodePos(float(gl_InstanceID));
float baseNodeSize = 8.0;
// Normalize camera distance into [0,1]
float t = clamp((camDist - 500.0) / (2000.0 - 500.0), 0.0, 1.0);
nodeSize = baseNodeSize * mix(10.0, 12.0, t);
vec3 transformed = nodePos + position * nodeSize;
gl_Position = projectionMatrix * modelViewMatrix * vec4(transformed, 1.0);
}
`,
fragmentShader: `
precision highp float;
varying vec2 vUv;
varying float nodeSize;
varying vec3 vColor;
void main() {
vec2 pCoord = vUv - 0.5;
float distSq = dot(pCoord, pCoord) * 4.0;
if (distSq > 1.0) {
discard;
}
float radiusSq = (nodeSize / 2.0) * (nodeSize / 2.0);
float falloff = max(0.0, 1.0 - distSq);
float influence = radiusSq * falloff * falloff;
vec3 accumulatedColor = vColor * influence;
gl_FragColor = vec4(accumulatedColor, influence);
}
`,
});
return densityCloudMaterial;
}
