refactor(environment): use player-centered ghibli grass patch

src/world/grass/GrassPatch.tsx

@@ -1,4 +1,5 @@
 import { useEffect, useMemo, useRef } from "react";
+import { useTexture } from "@react-three/drei";
 import { useFrame, useThree } from "@react-three/fiber";
 import * as THREE from "three";
 import { useWind } from "@/hooks/world/useWind";
@@ -10,8 +11,6 @@ import {
 import type { TerrainGrassSampler } from "@/world/grass/useTerrainGrassSampler";
 
 interface GrassPatchProps {
-  chunkX: number;
-  chunkZ: number;
   density: number;
   terrainSampler: TerrainGrassSampler;
 }
@@ -21,15 +20,126 @@ function random01(seed: number): number {
   return value - Math.floor(value);
 }
 
-function createGrassMaterial(): THREE.ShaderMaterial {
+function pushVector(target: number[], value: THREE.Vector3): void {
+  target.push(value.x, value.y, value.z);
+}
+
+function pushColor(target: number[], value: THREE.Color): void {
+  target.push(value.r, value.g, value.b);
+}
+
+function createGrassGeometry(density: number): THREE.BufferGeometry {
+  const positions: number[] = [];
+  const colors: number[] = [];
+  const uvs: number[] = [];
+  const bladeOrigins: number[] = [];
+  const yaws: number[] = [];
+  const bladeCount = Math.round(GRASS_CONFIG.bladeCount * density);
+  const halfPatchSize = GRASS_CONFIG.patchSize * 0.5;
+
+  for (let index = 0; index < bladeCount; index++) {
+    const seed = index * 997;
+    const origin = new THREE.Vector3(
+      random01(seed + 1) * GRASS_CONFIG.patchSize - halfPatchSize,
+      0,
+      random01(seed + 2) * GRASS_CONFIG.patchSize - halfPatchSize,
+    );
+    const yawAngle = random01(seed + 3) * Math.PI * 2;
+    const yaw = new THREE.Vector3(Math.sin(yawAngle), 0, -Math.cos(yawAngle));
+    const colorIndex = Math.floor(random01(seed + 4) * GRASS_COLORS.length);
+    const color = new THREE.Color(GRASS_COLORS[colorIndex] ?? GRASS_COLORS[0]);
+    const markerColors = [
+      new THREE.Color(0.1, 0, 0),
+      new THREE.Color(0, 0, 0.1),
+      new THREE.Color(1, 1, 1),
+    ] as const;
+    const uv = new THREE.Vector2(
+      origin.x / GRASS_CONFIG.patchSize + 0.5,
+      origin.z / GRASS_CONFIG.patchSize + 0.5,
+    );
+
+    for (let vertexIndex = 0; vertexIndex < 3; vertexIndex++) {
+      pushVector(positions, origin);
+      pushColor(colors, markerColors[vertexIndex] ?? markerColors[2]);
+      pushVector(bladeOrigins, origin);
+      pushVector(yaws, yaw);
+      pushColor(colors, color);
+      uvs.push(uv.x, uv.y);
+    }
+  }
+
+  const geometry = new THREE.BufferGeometry();
+  const markerColorValues: number[] = [];
+  const bladeColorValues: number[] = [];
+
+  for (let index = 0; index < colors.length; index += 6) {
+    markerColorValues.push(
+      colors[index] ?? 0,
+      colors[index + 1] ?? 0,
+      colors[index + 2] ?? 0,
+    );
+    bladeColorValues.push(
+      colors[index + 3] ?? 0,
+      colors[index + 4] ?? 0,
+      colors[index + 5] ?? 0,
+    );
+  }
+
+  geometry.setAttribute(
+    "position",
+    new THREE.Float32BufferAttribute(positions, 3),
+  );
+  geometry.setAttribute(
+    "color",
+    new THREE.Float32BufferAttribute(markerColorValues, 3),
+  );
+  geometry.setAttribute(
+    "aBladeColor",
+    new THREE.Float32BufferAttribute(bladeColorValues, 3),
+  );
+  geometry.setAttribute("uv", new THREE.Float32BufferAttribute(uvs, 2));
+  geometry.setAttribute(
+    "aBladeOrigin",
+    new THREE.Float32BufferAttribute(bladeOrigins, 3),
+  );
+  geometry.setAttribute("aYaw", new THREE.Float32BufferAttribute(yaws, 3));
+  geometry.computeVertexNormals();
+  geometry.computeBoundingSphere();
+
+  return geometry;
+}
+
+function createGrassMaterial(
+  terrainSampler: TerrainGrassSampler,
+  noiseTexture: THREE.Texture,
+  grassTexture: THREE.Texture,
+): THREE.ShaderMaterial {
   return new THREE.ShaderMaterial({
-    side: THREE.DoubleSide,
     vertexShader: grassVertexShader,
     fragmentShader: grassFragmentShader,
+    vertexColors: true,
+    side: THREE.DoubleSide,
     uniforms: {
       uTime: { value: 0 },
+      uNoiseTexture: { value: noiseTexture },
+      uDiffuseMap: { value: grassTexture },
+      uHeightMap: { value: terrainSampler.heightTexture },
       uPlayerPosition: { value: new THREE.Vector3() },
-      uPatchSize: { value: GRASS_CONFIG.chunkSize },
+      uBoundingBoxMin: {
+        value: new THREE.Vector3(
+          terrainSampler.bounds.minX,
+          terrainSampler.minHeight,
+          terrainSampler.bounds.minZ,
+        ),
+      },
+      uBoundingBoxMax: {
+        value: new THREE.Vector3(
+          terrainSampler.bounds.maxX,
+          terrainSampler.maxHeight,
+          terrainSampler.bounds.maxZ,
+        ),
+      },
+      uPatchSize: { value: GRASS_CONFIG.patchSize },
       uBladeWidth: { value: GRASS_CONFIG.bladeWidth },
       uWindDirection: { value: 0 },
       uWindSpeed: { value: 0 },
@@ -41,153 +151,51 @@ function createGrassMaterial(): THREE.ShaderMaterial {
       uMaxBendAngle: { value: GRASS_CONFIG.maxBendAngle },
       uMaxBladeHeight: { value: GRASS_CONFIG.maxBladeHeight },
       uRandomHeightAmount: { value: GRASS_CONFIG.randomHeightAmount },
+      uSurfaceOffset: { value: GRASS_CONFIG.surfaceOffset },
     },
   });
 }
 
-function pushVector(target: number[], value: THREE.Vector3): void {
-  target.push(value.x, value.y, value.z);
-}
-
-function pushColor(target: number[], value: THREE.Color): void {
-  target.push(value.r, value.g, value.b);
-}
-
-function addGrassBlade(
-  positions: number[],
-  bladeColors: number[],
-  bladeBases: number[],
-  bladeNormals: number[],
-  sideFactors: number[],
-  tipFactors: number[],
-  randoms: number[],
-  yaws: number[],
-  basePosition: THREE.Vector3,
-  normal: THREE.Vector3,
-  color: THREE.Color,
-  yaw: THREE.Vector3,
-  random: number,
-): void {
-  const vertices = [
-    { side: 1, tip: 0 },
-    { side: -1, tip: 0 },
-    { side: 0, tip: 1 },
-  ];
-
-  for (const vertex of vertices) {
-    pushVector(positions, basePosition);
-    pushColor(bladeColors, color);
-    pushVector(bladeBases, basePosition);
-    pushVector(bladeNormals, normal);
-    pushVector(yaws, yaw);
-    sideFactors.push(vertex.side);
-    tipFactors.push(vertex.tip);
-    randoms.push(random);
-  }
-}
-
-function createGrassGeometry(
-  chunkX: number,
-  chunkZ: number,
-  density: number,
-  terrainSampler: TerrainGrassSampler,
-): THREE.BufferGeometry | null {
-  const positions: number[] = [];
-  const bladeColors: number[] = [];
-  const bladeBases: number[] = [];
-  const bladeNormals: number[] = [];
-  const sideFactors: number[] = [];
-  const tipFactors: number[] = [];
-  const randoms: number[] = [];
-  const yaws: number[] = [];
-  const startX = chunkX * GRASS_CONFIG.chunkSize;
-  const startZ = chunkZ * GRASS_CONFIG.chunkSize;
-  const bladeCount = Math.round(GRASS_CONFIG.baseBladesPerChunk * density);
-
-  for (let index = 0; index < bladeCount; index++) {
-    const seed = (chunkX + 101) * 92821 + (chunkZ + 103) * 68917 + index * 997;
-    const x = startX + random01(seed + 1) * GRASS_CONFIG.chunkSize;
-    const z = startZ + random01(seed + 2) * GRASS_CONFIG.chunkSize;
-    const sample = terrainSampler.sample(x, z);
-    if (!sample) continue;
-
-    const colorIndex = Math.floor(random01(seed + 3) * GRASS_COLORS.length);
-    const color = new THREE.Color(GRASS_COLORS[colorIndex] ?? GRASS_COLORS[0]);
-    const yawAngle = random01(seed + 4) * Math.PI * 2;
-    const yaw = new THREE.Vector3(Math.sin(yawAngle), 0, -Math.cos(yawAngle));
-    const basePosition = sample.position
-      .clone()
-      .addScaledVector(sample.normal, GRASS_CONFIG.surfaceOffset);
-
-    addGrassBlade(
-      positions,
-      bladeColors,
-      bladeBases,
-      bladeNormals,
-      sideFactors,
-      tipFactors,
-      randoms,
-      yaws,
-      basePosition,
-      sample.normal,
-      color,
-      yaw,
-      random01(seed + 5),
-    );
-  }
-
-  if (positions.length === 0) return null;
-
-  const geometry = new THREE.BufferGeometry();
-  geometry.setAttribute(
-    "position",
-    new THREE.Float32BufferAttribute(positions, 3),
-  );
-  geometry.setAttribute(
-    "aBladeColor",
-    new THREE.Float32BufferAttribute(bladeColors, 3),
-  );
-  geometry.setAttribute(
-    "aBladeBase",
-    new THREE.Float32BufferAttribute(bladeBases, 3),
-  );
-  geometry.setAttribute(
-    "aBladeNormal",
-    new THREE.Float32BufferAttribute(bladeNormals, 3),
-  );
-  geometry.setAttribute(
-    "aSideFactor",
-    new THREE.Float32BufferAttribute(sideFactors, 1),
-  );
-  geometry.setAttribute(
-    "aTipFactor",
-    new THREE.Float32BufferAttribute(tipFactors, 1),
-  );
-  geometry.setAttribute(
-    "aRandom",
-    new THREE.Float32BufferAttribute(randoms, 1),
-  );
-  geometry.setAttribute("aYaw", new THREE.Float32BufferAttribute(yaws, 3));
-  geometry.computeVertexNormals();
-  geometry.computeBoundingSphere();
-
-  return geometry;
-}
-
 export function GrassPatch({
-  chunkX,
-  chunkZ,
   density,
   terrainSampler,
-}: GrassPatchProps): React.JSX.Element | null {
+}: GrassPatchProps): React.JSX.Element {
   const camera = useThree((state) => state.camera);
   const wind = useWind();
+  const [noiseTexture, grassTexture] = useTexture([
+    "/textures/grass/noise.png",
+    "/textures/grass/grass.jpg",
+  ]) as [THREE.Texture, THREE.Texture];
+  const grassTextures = useMemo(() => {
+    const noise = noiseTexture.clone();
+    const grass = grassTexture.clone();
+
+    noise.wrapS = noise.wrapT = THREE.RepeatWrapping;
+    grass.wrapS = grass.wrapT = THREE.MirroredRepeatWrapping;
+    noise.needsUpdate = true;
+    grass.needsUpdate = true;
+
+    return { grass, noise };
+  }, [grassTexture, noiseTexture]);
   const materialRef = useRef<THREE.ShaderMaterial | null>(null);
-  const geometry = useMemo(
-    () => createGrassGeometry(chunkX, chunkZ, density, terrainSampler),
-    [chunkX, chunkZ, density, terrainSampler],
+  const geometry = useMemo(() => createGrassGeometry(density), [density]);
+
+  useEffect(() => {
+    return () => {
+      grassTextures.grass.dispose();
+      grassTextures.noise.dispose();
+    };
+  }, [grassTextures]);
+
+  const material = useMemo(
+    () =>
+      createGrassMaterial(
+        terrainSampler,
+        grassTextures.noise,
+        grassTextures.grass,
+      ),
+    [grassTextures, terrainSampler],
   );
-  const material = useMemo(() => createGrassMaterial(), []);
 
   useEffect(() => {
     materialRef.current = material;
@@ -199,7 +207,7 @@ export function GrassPatch({
 
   useEffect(() => {
     return () => {
-      geometry?.dispose();
+      geometry.dispose();
     };
   }, [geometry]);
 
@@ -220,7 +228,5 @@ export function GrassPatch({
     }
   });
 
-  if (!geometry) return null;
-
   return <mesh geometry={geometry} material={material} frustumCulled={false} />;
 }

src/world/grass/GrassSystem.tsx

@@ -1,146 +1,25 @@
-import { Suspense, useCallback, useMemo, useRef, useState } from "react";
-import { useFrame, useThree } from "@react-three/fiber";
-import { useSceneMode } from "@/hooks/debug/useSceneMode";
+import { Suspense } from "react";
 import {
   useDynamicGrass,
   useGrassDensity,
 } from "@/hooks/world/useGraphicsSettings";
-import type { TerrainSurfaceBounds } from "@/types/world/terrainSurface";
 import { GRASS_CONFIG } from "@/world/grass/grassConfig";
 import { GrassPatch } from "@/world/grass/GrassPatch";
 import { useTerrainGrassSampler } from "@/world/grass/useTerrainGrassSampler";
 
-interface GrassChunk {
-  centerX: number;
-  centerZ: number;
-  key: string;
-  x: number;
-  z: number;
-}
-
-function getChunkRange(min: number, max: number): number[] {
-  const start = Math.floor(min / GRASS_CONFIG.chunkSize);
-  const end = Math.floor(max / GRASS_CONFIG.chunkSize);
-  const chunks: number[] = [];
-
-  for (let value = start; value <= end; value++) {
-    chunks.push(value);
-  }
-
-  return chunks;
-}
-
-function createGrassChunks(bounds: TerrainSurfaceBounds): GrassChunk[] {
-  const chunks: GrassChunk[] = [];
-  const xChunks = getChunkRange(bounds.minX, bounds.maxX);
-  const zChunks = getChunkRange(bounds.minZ, bounds.maxZ);
-
-  for (const x of xChunks) {
-    for (const z of zChunks) {
-      chunks.push({
-        centerX: x * GRASS_CONFIG.chunkSize + GRASS_CONFIG.chunkSize * 0.5,
-        centerZ: z * GRASS_CONFIG.chunkSize + GRASS_CONFIG.chunkSize * 0.5,
-        key: `${x}:${z}`,
-        x,
-        z,
-      });
-    }
-  }
-
-  return chunks;
-}
-
 export function GrassSystem(): React.JSX.Element | null {
-  const camera = useThree((state) => state.camera);
   const terrainSampler = useTerrainGrassSampler();
-  const sceneMode = useSceneMode();
   const dynamicGrass = useDynamicGrass();
   const grassDensity = useGrassDensity();
-  const lastUpdateRef = useRef(-GRASS_CONFIG.updateInterval);
-  const [activeChunkKeys, setActiveChunkKeys] = useState<Set<string>>(
-    () => new Set(),
-  );
   const density = Math.max(0, grassDensity);
-  const chunks = useMemo(
-    () => createGrassChunks(terrainSampler.bounds),
-    [terrainSampler],
-  );
-  const streamingEnabled = sceneMode === "game";
 
-  const updateActiveChunks = useCallback(() => {
-    const nextKeys = new Set<string>();
-
-    for (const chunk of chunks) {
-      const distance = Math.hypot(
-        chunk.centerX - camera.position.x,
-        chunk.centerZ - camera.position.z,
-      );
-      const wasActive = activeChunkKeys.has(chunk.key);
-      const radius = wasActive
-        ? GRASS_CONFIG.unloadRadius
-        : GRASS_CONFIG.loadRadius;
-
-      if (distance <= radius) {
-        nextKeys.add(chunk.key);
-      }
-    }
-
-    if (
-      nextKeys.size === activeChunkKeys.size &&
-      [...nextKeys].every((key) => activeChunkKeys.has(key))
-    ) {
-      return;
-    }
-
-    setActiveChunkKeys(nextKeys);
-  }, [activeChunkKeys, camera, chunks]);
-
-  useFrame(({ clock }) => {
-    if (!streamingEnabled) return;
-
-    const now = clock.elapsedTime * 1000;
-    if (now - lastUpdateRef.current < GRASS_CONFIG.updateInterval) return;
-    lastUpdateRef.current = now;
-
-    updateActiveChunks();
-  });
-
-  if (
-    !GRASS_CONFIG.enabled ||
-    !dynamicGrass ||
-    density <= 0 ||
-    chunks.length === 0
-  ) {
+  if (!GRASS_CONFIG.enabled || !dynamicGrass || density <= 0) {
     return null;
   }
 
-  const visibleChunks = streamingEnabled
-    ? chunks.filter((chunk) => {
-        if (activeChunkKeys.size > 0) {
-          return activeChunkKeys.has(chunk.key);
-        }
-
   return (
-          Math.hypot(
-            chunk.centerX - camera.position.x,
-            chunk.centerZ - camera.position.z,
-          ) <= GRASS_CONFIG.loadRadius
-        );
-      })
-    : chunks;
-
-  return (
-    <group name="grass-system">
-      {visibleChunks.map((chunk) => (
-        <Suspense key={chunk.key} fallback={null}>
-          <GrassPatch
-            chunkX={chunk.x}
-            chunkZ={chunk.z}
-            density={density}
-            terrainSampler={terrainSampler}
-          />
+    <Suspense fallback={null}>
+      <GrassPatch density={density} terrainSampler={terrainSampler} />
     </Suspense>
-      ))}
-    </group>
   );
 }

src/world/grass/grassConfig.ts

@@ -1,14 +1,12 @@
 export const GRASS_CONFIG = {
   enabled: true,
-  chunkSize: 20,
-  loadRadius: 30,
-  unloadRadius: 34,
-  updateInterval: 250,
-  baseBladesPerChunk: 420,
+  patchSize: 30,
+  bladeCount: 18000,
   bladeWidth: 0.08,
   maxBladeHeight: 0.36,
   randomHeightAmount: 0.25,
   surfaceOffset: 0.025,
+  heightTextureSize: 128,
   windNoiseScale: 0.9,
   baldPatchModifier: 2.5,
   falloffSharpness: 0.35,

src/world/grass/grassShaders.ts

@@ -1,16 +1,17 @@
 export const grassVertexShader = /* glsl */ `
-  attribute vec3 aBladeColor;
-  attribute vec3 aBladeNormal;
-  attribute vec3 aBladeBase;
-  attribute float aSideFactor;
-  attribute float aTipFactor;
-  attribute float aRandom;
   attribute vec3 aYaw;
+  attribute vec3 aBladeOrigin;
+  attribute vec3 aBladeColor;
 
   varying vec3 vColor;
 
   uniform float uTime;
   uniform vec3 uPlayerPosition;
+  uniform sampler2D uHeightMap;
+  uniform sampler2D uDiffuseMap;
+  uniform sampler2D uNoiseTexture;
+  uniform vec3 uBoundingBoxMin;
+  uniform vec3 uBoundingBoxMax;
   uniform float uPatchSize;
   uniform float uBladeWidth;
   uniform float uWindDirection;
@@ -23,6 +24,7 @@ export const grassVertexShader = /* glsl */ `
   uniform float uMaxBendAngle;
   uniform float uMaxBladeHeight;
   uniform float uRandomHeightAmount;
+  uniform float uSurfaceOffset;
 
   float random(vec2 st) {
     return fract(sin(dot(st.xy, vec2(12.9898, 78.233))) * 43758.5453123);
@@ -45,33 +47,59 @@ export const grassVertexShader = /* glsl */ `
   }
 
   void main() {
-    vec3 origin = aBladeBase;
-    vec3 transformed = origin;
+    vec3 transformed = position;
+    vec3 origin = aBladeOrigin;
     float halfPatchSize = uPatchSize * 0.5;
-    vec2 uv = vec2(origin.x, origin.z) * 0.05;
 
-    float heightNoise =
-      random(floor(uv * uHeightNoiseFrequency) + aRandom) *
-      uMaxBladeHeight *
-      uHeightNoiseAmplitude;
-    float heightModifier = heightNoise + random(uv + aRandom) * (uRandomHeightAmount * 0.1);
+    origin.x = mod(origin.x - uPlayerPosition.x + halfPatchSize, uPatchSize) - halfPatchSize;
+    origin.z = mod(origin.z - uPlayerPosition.z + halfPatchSize, uPatchSize) - halfPatchSize;
 
-    float edgeDistanceX = abs(origin.x - uPlayerPosition.x) / halfPatchSize;
-    float edgeDistanceZ = abs(origin.z - uPlayerPosition.z) / halfPatchSize;
+    vec3 worldPos = vec3(uPlayerPosition.x + origin.x, 0.0, uPlayerPosition.z + origin.z);
+    transformed.x = worldPos.x;
+    transformed.z = worldPos.z;
+
+    vec2 terrainUv = vec2(
+      mapValue(worldPos.x, uBoundingBoxMin.x, uBoundingBoxMax.x, 0.0, 1.0),
+      mapValue(worldPos.z, uBoundingBoxMin.z, uBoundingBoxMax.z, 0.0, 1.0)
+    );
+    terrainUv = clamp(terrainUv, 0.0, 1.0);
+
+    float terrainHeightRatio = texture2D(uHeightMap, terrainUv).r;
+    float terrainHeight = mix(uBoundingBoxMin.y, uBoundingBoxMax.y, terrainHeightRatio);
+    transformed.y = terrainHeight + uSurfaceOffset;
+
+    vec3 heightNoise = texture2D(uNoiseTexture, terrainUv.yx * vec2(uHeightNoiseFrequency)).rgb;
+    float heightModifier = ((heightNoise.r + heightNoise.g + heightNoise.b) * uMaxBladeHeight) * uHeightNoiseAmplitude;
+    heightModifier += random(terrainUv) * (uRandomHeightAmount * 0.1);
+
+    float edgeDistanceX = abs(origin.x) / halfPatchSize;
+    float edgeDistanceZ = abs(origin.z) / halfPatchSize;
     float edgeFactor = 1.0 - max(edgeDistanceX, edgeDistanceZ);
     edgeFactor = pow(clamp(edgeFactor, 0.0, 1.0), uFalloffSharpness);
 
-    float baldPatch = random(floor(uv * 3.0)) * (uBaldPatchModifier * (1.0 - edgeFactor));
-    heightModifier = max(0.0, heightModifier - baldPatch);
+    float baldPatchOffset = heightNoise.r * (uBaldPatchModifier * (1.0 - edgeFactor));
+    heightModifier -= baldPatchOffset;
 
-    float distanceFromCenter = length(origin.xz - uPlayerPosition.xz) / halfPatchSize;
+    float edgeFade =
+      smoothstep(uBoundingBoxMin.x, uBoundingBoxMin.x + 2.0, worldPos.x) *
+      smoothstep(uBoundingBoxMax.x, uBoundingBoxMax.x - 2.0, worldPos.x) *
+      smoothstep(uBoundingBoxMin.z, uBoundingBoxMin.z + 2.0, worldPos.z) *
+      smoothstep(uBoundingBoxMax.z, uBoundingBoxMax.z - 2.0, worldPos.z);
+    heightModifier *= edgeFade;
+
+    float sideFactor = (color.r == 0.1) ? 1.0 : (color.b == 0.1) ? -1.0 : 0.0;
+    float tipFactor = color.g;
+    float width = smoothstep(0.5, 1.0, heightModifier * 2.0) * uBladeWidth;
+    transformed += aYaw * (width / 2.0) * sideFactor;
+
+    vec3 textureColor = texture2D(uDiffuseMap, terrainUv * 10.0).rgb;
+    vec3 colorNoise = texture2D(uNoiseTexture, terrainUv.yx * vec2(uHeightNoiseFrequency) + (uTime * 0.1)).rgb;
+    vColor = mix(aBladeColor * 0.55, aBladeColor, tipFactor) * textureColor * mix(vec3(0.75), vec3(1.15), colorNoise);
+
+    float distanceFromCenter = length(origin.xz) / halfPatchSize;
     float innerCircleFactor = clamp(smoothstep(0.0, 0.5, distanceFromCenter), 0.0, 1.0);
     heightModifier *= mix(0.25, 1.0, innerCircleFactor);
 
-    vec3 tangent = normalize(aYaw - aBladeNormal * dot(aYaw, aBladeNormal));
-    transformed += tangent * (uBladeWidth * 0.5) * aSideFactor;
-    transformed += aBladeNormal * heightModifier * aTipFactor;
-
     float noiseScale = uWindNoiseScale * 0.1;
     vec2 noiseUV = vec2(origin.x * noiseScale, origin.z * noiseScale);
     mat2 rotation = mat2(
@@ -79,20 +107,18 @@ export const grassVertexShader = /* glsl */ `
       sin(uWindDirection), cos(uWindDirection)
     );
     vec2 rotatedNoiseUV = rotation * noiseUV + uTime * vec2(uWindSpeed);
-    float windA = random(floor(rotatedNoiseUV * 10.0));
-    float windB = random(floor(rotatedNoiseUV.yx * 10.0 + 17.0));
-    vec3 axis = normalize(vec3(windA, 0.0, windB));
-    float angle = radians(mapValue(windA + windB, 0.0, 2.0, -uMaxBendAngle, uMaxBendAngle)) * aTipFactor;
+    vec3 windNoise = texture2D(uNoiseTexture, rotatedNoiseUV).rgb;
+
+    vec3 axis = vec3(windNoise.g, 0.0, windNoise.b);
+    float angle = radians(mapValue(windNoise.g + windNoise.b, 0.0, 2.0, -uMaxBendAngle, uMaxBendAngle)) * tipFactor;
     mat3 rotationMatrix = rotate3d(axis, angle);
 
-    vec3 relativePosition = transformed - origin;
+    vec3 basePosition = vec3(transformed.x, transformed.y - heightModifier, transformed.z);
+    vec3 relativePosition = transformed - basePosition;
     relativePosition = rotationMatrix * relativePosition;
-    transformed = origin + relativePosition;
+    transformed = basePosition + relativePosition;
+    transformed.y += heightModifier * tipFactor;
 
-    vec3 baseColor = aBladeColor * 0.45;
-    vec3 tipColor = aBladeColor;
-    float shadeNoise = random(floor((uv + uTime * 0.01) * 24.0));
-    vColor = mix(baseColor, tipColor, aTipFactor) * mix(0.72, 1.08, shadeNoise);
     gl_Position = projectionMatrix * modelViewMatrix * vec4(transformed, 1.0);
   }
 `;

src/world/grass/useTerrainGrassSampler.ts

@@ -5,6 +5,7 @@ import { TERRAIN_MODEL_PATH } from "@/data/world/terrainConfig";
 import type { TerrainSurfaceBounds } from "@/types/world/terrainSurface";
 import type { Vector3Tuple } from "@/types/three/three";
 import { getMapNodesByName } from "@/utils/map/loadMapSceneData";
+import { GRASS_CONFIG } from "@/world/grass/grassConfig";
 
 const RAYCAST_Y = 500;
 const RAYCAST_FAR = 1000;
@@ -20,6 +21,9 @@ export interface TerrainGrassSample {
 
 export interface TerrainGrassSampler {
   bounds: TerrainSurfaceBounds;
+  heightTexture: THREE.DataTexture;
+  maxHeight: number;
+  minHeight: number;
   sample: (x: number, z: number) => TerrainGrassSample | null;
 }
 
@@ -82,9 +86,7 @@ function createTerrainGrassSampler(
         maxZ: terrainBounds.max.z,
       };
 
-  return {
-    bounds,
-    sample: (x, z) => {
+  const sample = (x: number, z: number): TerrainGrassSample | null => {
     const localOrigin = new THREE.Vector3(x, RAYCAST_Y, z).applyMatrix4(
       inverseTerrainMatrix,
     );
@@ -105,8 +107,75 @@ function createTerrainGrassSampler(
       position: hit.point.clone().applyMatrix4(terrainMatrix),
       normal: normal ?? new THREE.Vector3(0, 1, 0),
     };
-    },
   };
+
+  const { heightTexture, maxHeight, minHeight } = createTerrainHeightTexture(
+    bounds,
+    sample,
+  );
+
+  return {
+    bounds,
+    heightTexture,
+    maxHeight,
+    minHeight,
+    sample,
+  };
+}
+
+function createTerrainHeightTexture(
+  bounds: TerrainSurfaceBounds,
+  sample: (x: number, z: number) => TerrainGrassSample | null,
+): { heightTexture: THREE.DataTexture; maxHeight: number; minHeight: number } {
+  const size = GRASS_CONFIG.heightTextureSize;
+  const heights = new Float32Array(size * size);
+  let minHeight = Number.POSITIVE_INFINITY;
+  let maxHeight = Number.NEGATIVE_INFINITY;
+
+  for (let zIndex = 0; zIndex < size; zIndex++) {
+    for (let xIndex = 0; xIndex < size; xIndex++) {
+      const xRatio = size <= 1 ? 0 : xIndex / (size - 1);
+      const zRatio = size <= 1 ? 0 : zIndex / (size - 1);
+      const x = bounds.minX + (bounds.maxX - bounds.minX) * xRatio;
+      const z = bounds.minZ + (bounds.maxZ - bounds.minZ) * zRatio;
+      const terrainSample = sample(x, z);
+      const height = terrainSample?.position.y ?? 0;
+      const index = zIndex * size + xIndex;
+
+      heights[index] = height;
+      minHeight = Math.min(minHeight, height);
+      maxHeight = Math.max(maxHeight, height);
+    }
+  }
+
+  if (!Number.isFinite(minHeight) || !Number.isFinite(maxHeight)) {
+    minHeight = 0;
+    maxHeight = 1;
+  }
+
+  const range = Math.max(maxHeight - minHeight, 0.0001);
+  const data = new Uint8Array(size * size);
+
+  for (let index = 0; index < heights.length; index++) {
+    data[index] = Math.round(
+      (((heights[index] ?? minHeight) - minHeight) / range) * 255,
+    );
+  }
+
+  const heightTexture = new THREE.DataTexture(
+    data,
+    size,
+    size,
+    THREE.RedFormat,
+    THREE.UnsignedByteType,
+  );
+  heightTexture.magFilter = THREE.LinearFilter;
+  heightTexture.minFilter = THREE.LinearFilter;
+  heightTexture.wrapS = THREE.ClampToEdgeWrapping;
+  heightTexture.wrapT = THREE.ClampToEdgeWrapping;
+  heightTexture.needsUpdate = true;
+
+  return { heightTexture, maxHeight, minHeight };
 }
 
 export function useTerrainGrassSampler(): TerrainGrassSampler {