geometry-texture-atlas.js

import * as THREE from 'three';
import {MaxRectsPacker} from 'maxrects-packer';
import {getRenderer} from './renderer.js';
import {modUv} from './util.js';

const defaultTextureSize = 4096;
const startAtlasSize = 512;

const localVector2D = new THREE.Vector2();
const localVector2D2 = new THREE.Vector2();

const textureTypes = ['map', 'emissiveMap', 'normalMap', 'shadeTexture'];

class AttributeLayout {
  constructor(name, TypedArrayConstructor, itemSize) {
    this.name = name;
    this.TypedArrayConstructor = TypedArrayConstructor;
    this.itemSize = itemSize;

    this.count = 0;
  }
  makeDefault(g) {
    return new THREE.BufferAttribute(
      new this.TypedArrayConstructor(
        g.attributes.position.count * this.itemSize,
      ),
      this.itemSize,
    );
  }
}
class MorphAttributeLayout extends AttributeLayout {
  constructor(name, TypedArrayConstructor, itemSize, arraySize) {
    super(name, TypedArrayConstructor, itemSize);
    this.arraySize = arraySize;
  }
  makeDefault(g) {
    return Array(this.arraySize).fill(super.makeDefault(g));
  }
}

const getObjectKeyDefault = (type, object, material) => {
  const renderer = getRenderer();
  return [type, renderer.getProgramCacheKey(object, material)].join(',');
};
export const getMergeableObjects = (
  model,
  getObjectKey = getObjectKeyDefault,
) => {
  const mergeables = new Map();
  model.traverse(o => {
    if (o.isMesh && o.geometry.type === 'BufferGeometry') {
      let type;
      if (o.isSkinnedMesh) {
        type = 'skinnedMesh';
      } else {
        type = 'mesh';
      }

      const objectGeometry = o.geometry;
      const morphTargetDictionary = o.morphTargetDictionary;
      const morphTargetInfluences = o.morphTargetInfluences;
      const objectMaterials = Array.isArray(o.material)
        ? o.material
        : [o.material];
      for (const objectMaterial of objectMaterials) {
        const {
          map = null,
          emissiveMap = null,
          normalMap = null,
          shadeTexture = null,
        } = objectMaterial;
        const skeleton = o.skeleton ?? null;

        const key = getObjectKey(type, o, objectMaterial);

        let m = mergeables.get(key);
        if (!m) {
          m = {
            type,
            material: objectMaterial,
            geometries: [],
            maps: [],
            emissiveMaps: [],
            normalMaps: [],
            shadeTextures: [],
            skeletons: [],
            morphTargetDictionaryArray: [],
            morphTargetInfluencesArray: [],
          };
          mergeables.set(key, m);
        }

        m.geometries.push(objectGeometry);
        m.maps.push(map);
        m.emissiveMaps.push(emissiveMap);
        m.normalMaps.push(normalMap);
        m.shadeTextures.push(shadeTexture);
        m.skeletons.push(skeleton);
        m.morphTargetDictionaryArray.push(morphTargetDictionary);
        m.morphTargetInfluencesArray.push(morphTargetInfluences);
      }
    }
  });
  return Array.from(mergeables.values());
};

export const mergeGeometryTextureAtlas = (mergeable, textureSize) => {
  const {
    type,
    material,
    geometries,
    maps,
    emissiveMaps,
    normalMaps,
    skeletons,
    morphTargetDictionaryArray,
    morphTargetInfluencesArray,
  } = mergeable;

  // compute texture sizes
  const textureSizes = maps.map((map, i) => {
    const emissiveMap = emissiveMaps[i];
    const normalMap = normalMaps[i];

    const maxSize = new THREE.Vector2(0, 0);
    if (map) {
      maxSize.x = Math.max(maxSize.x, map.image.width);
      maxSize.y = Math.max(maxSize.y, map.image.height);
    }
    if (emissiveMap) {
      maxSize.x = Math.max(maxSize.x, emissiveMap.image.width);
      maxSize.y = Math.max(maxSize.y, emissiveMap.image.height);
    }
    if (normalMap) {
      maxSize.x = Math.max(maxSize.x, normalMap.image.width);
      maxSize.y = Math.max(maxSize.y, normalMap.image.height);
    }
    return maxSize;
  });

  // generate atlas layouts
  const _packAtlases = () => {
    const _attemptPack = (textureSizes, atlasSize) => {
      const maxRectsPacker = new MaxRectsPacker(atlasSize, atlasSize, 1);
      const rects = textureSizes.map((textureSize, index) => {
        const {x: width, y: height} = textureSize;
        return {
          width,
          height,
          data: {
            index,
          },
        };
      });
      maxRectsPacker.addArray(rects);
      let oversized = maxRectsPacker.bins.length > 1;
      maxRectsPacker.bins.forEach(bin => {
        bin.rects.forEach(rect => {
          if (rect.oversized) {
            oversized = true;
          }
        });
      });
      if (!oversized) {
        return maxRectsPacker;
      } else {
        return null;
      }
    };

    const hasTextures = textureSizes.some(
      textureSize => textureSize.x > 0 || textureSize.y > 0,
    );
    if (hasTextures) {
      let atlas;
      let atlasSize = startAtlasSize;
      while (!(atlas = _attemptPack(textureSizes, atlasSize))) {
        atlasSize *= 2;
      }
      return atlas;
    } else {
      return null;
    }
  };
  const atlas = _packAtlases();

  // draw atlas images
  const originalTextures = new Map(); // map of canvas to the texture that generated it
  const _drawAtlasImages = atlas => {
    const _getTexturesKey = textures =>
      textures.map(t => (t ? t.uuid : '')).join(',');
    const _drawAtlasImage = textures => {
      if (atlas && textures.some(t => t !== null)) {
        const canvasSize = Math.min(atlas.width, textureSize);
        const canvasScale = canvasSize / atlas.width;

        const canvas = document.createElement('canvas');
        canvas.width = canvasSize;
        canvas.height = canvasSize;
        const ctx = canvas.getContext('2d');

        atlas.bins.forEach(bin => {
          bin.rects.forEach(rect => {
            const {
              x,
              y,
              width: w,
              height: h,
              data: {index},
            } = rect;
            const texture = textures[index];
            if (texture) {
              const image = texture.image;

              // draw the image in the correct box on the canvas
              const tx = x * canvasScale;
              const ty = y * canvasScale;
              const tw = w * canvasScale;
              const th = h * canvasScale;
              ctx.drawImage(
                image,
                0,
                0,
                image.width,
                image.height,
                tx,
                ty,
                tw,
                th,
              );

              if (!originalTextures.has(canvas)) {
                originalTextures.set(canvas, texture);
              }
            }
          });
        });

        return canvas;
      } else {
        return null;
      }
    };

    const atlasImages = {};
    const atlasImagesMap = new Map(); // cache to alias identical textures
    for (const textureType of textureTypes) {
      const textures = mergeable[`${textureType}s`];
      const key = _getTexturesKey(textures);

      let atlasImage = atlasImagesMap.get(key);
      if (atlasImage === undefined) {
        // cache miss
        atlasImage = _drawAtlasImage(textures);
        if (atlasImage !== null) {
          atlasImage.key = key;
        }
        atlasImagesMap.set(key, atlasImage);
      }
      atlasImages[textureType] = atlasImage;
    }
    return atlasImages;
  };
  const atlasImages = _drawAtlasImages(atlas);

  /* // XXX debug
  {
    const debugWidth = 300;
    let textureTypeIndex = 0;
    for (const textureType of textureTypes) {
      const atlasImage = atlasImages[textureType];
      if (atlasImage) {
        atlasImage.style.cssText = `\
          position: fixed;
          top: ${mergeableIndex * debugWidth}px;
          left: ${textureTypeIndex * debugWidth}px;
          min-width: ${debugWidth}px;
          max-width: ${debugWidth}px;
          min-height: ${debugWidth}px;
          z-index: 100;
        `;
        atlasImage.setAttribute('type', textureType);
        document.body.appendChild(atlasImage);
        textureTypeIndex++;
      }
    }
  } */

  // build attribute layouts
  const _makeAttributeLayoutsFromGeometries = geometries => {
    const attributeLayouts = [];
    for (const g of geometries) {
      const attributes = g.attributes;
      for (const attributeName in attributes) {
        const attribute = attributes[attributeName];
        let layout = attributeLayouts.find(
          layout => layout.name === attributeName,
        );
        if (layout) {
          // sanity check that item size is the same
          if (layout.itemSize !== attribute.itemSize) {
            throw new Error(
              `attribute ${attributeName} has different itemSize: ${layout.itemSize}, ${attribute.itemSize}`,
            );
          }
        } else {
          layout = new AttributeLayout(
            attributeName,
            attribute.array.constructor,
            attribute.itemSize,
          );
          attributeLayouts.push(layout);
        }

        layout.count += attribute.count * attribute.itemSize;
      }
    }
    return attributeLayouts;
  };
  const attributeLayouts = _makeAttributeLayoutsFromGeometries(geometries);

  const _makeMorphAttributeLayoutsFromGeometries = geometries => {
    // create morph layouts
    const morphAttributeLayouts = [];
    for (const g of geometries) {
      const morphAttributes = g.morphAttributes;
      for (const morphAttributeName in morphAttributes) {
        const morphAttribute = morphAttributes[morphAttributeName];
        let morphLayout = morphAttributeLayouts.find(
          l => l.name === morphAttributeName,
        );
        if (!morphLayout) {
          morphLayout = new MorphAttributeLayout(
            morphAttributeName,
            morphAttribute[0].array.constructor,
            morphAttribute[0].itemSize,
            morphAttribute.length,
          );
          morphAttributeLayouts.push(morphLayout);
        }

        morphLayout.count +=
          morphAttribute[0].count * morphAttribute[0].itemSize;
      }
    }
    return morphAttributeLayouts;
  };
  const morphAttributeLayouts =
    _makeMorphAttributeLayoutsFromGeometries(geometries);
  // console.log('got attribute layouts', attributeLayouts, morphAttributeLayouts);

  const _forceGeometriesAttributeLayouts = (attributeLayouts, geometries) => {
    for (const layout of attributeLayouts) {
      for (const g of geometries) {
        let gAttribute = g.attributes[layout.name];
        if (!gAttribute) {
          if (layout.name === 'skinIndex' || layout.name === 'skinWeight') {
            gAttribute = layout.makeDefault(g);
            g.setAttribute(layout.name, gAttribute);

            layout.count += gAttribute.count * gAttribute.itemSize;
          } else {
            throw new Error(`unknown layout ${layout.name}`);
          }
        }
      }
    }

    for (const morphLayout of morphAttributeLayouts) {
      for (const g of geometries) {
        let morphAttribute = g.morphAttributes[morphLayout.name];
        if (!morphAttribute) {
          // console.log('missing morph attribute', morphLayout, morphAttribute);

          morphAttribute = morphLayout.makeDefault(g);
          g.morphAttributes[morphLayout.name] = morphAttribute;

          morphLayout.count +=
            morphAttribute[0].count * morphAttribute[0].itemSize;

          /* if (layout.name === 'skinIndex' || layout.name === 'skinWeight') {
            gAttribute = new THREE.BufferAttribute(new Float32Array(g.attributes.position.count * layout.itemSize), layout.itemSize);
            g.setAttribute(layout.name, gAttribute);
          } else {
            throw new Error(`unknown layout ${layout.name}`);
          } */
        }
      }
    }
  };
  const _mergeAttributes = (geometry, geometries, attributeLayouts) => {
    for (const layout of attributeLayouts) {
      const attributeData = new layout.TypedArrayConstructor(layout.count);
      const attribute = new THREE.BufferAttribute(
        attributeData,
        layout.itemSize,
      );
      let attributeDataIndex = 0;
      for (const g of geometries) {
        const gAttribute = g.attributes[layout.name];
        attributeData.set(gAttribute.array, attributeDataIndex);
        attributeDataIndex += gAttribute.count * gAttribute.itemSize;
      }
      // sanity check
      if (attributeDataIndex !== layout.count) {
        console.warn(
          'desynced attribute data 1',
          layout.name,
          attributeDataIndex,
          layout.count,
        );
        debugger;
      }
      geometry.setAttribute(layout.name, attribute);
    }
  };
  const _mergeMorphAttributes = (
    geometry,
    geometries,
    morphAttributeLayouts,
  ) => {
    for (const morphLayout of morphAttributeLayouts) {
      const morphsArray = Array(morphLayout.arraySize);
      for (let i = 0; i < morphLayout.arraySize; i++) {
        const morphData = new morphLayout.TypedArrayConstructor(
          morphLayout.count,
        );
        const morphAttribute = new THREE.BufferAttribute(
          morphData,
          morphLayout.itemSize,
        );
        morphsArray[i] = morphAttribute;
        let morphDataIndex = 0;
        for (const g of geometries) {
          let gMorphAttribute = g.morphAttributes[morphLayout.name];
          gMorphAttribute = gMorphAttribute?.[i];
          if (gMorphAttribute) {
            morphData.set(gMorphAttribute.array, morphDataIndex);
            morphDataIndex += gMorphAttribute.count * gMorphAttribute.itemSize;
          } else {
            const matchingAttribute = g.attributes[morphLayout.name];
            morphDataIndex +=
              matchingAttribute.count * matchingAttribute.itemSize;
          }
        }
        // sanity check
        if (morphDataIndex !== morphLayout.count) {
          console.warn(
            'desynced morph data 2',
            morphLayout.name,
            morphDataIndex,
            morphLayout.count,
          );
        }
      }
      geometry.morphAttributes[morphLayout.name] = morphsArray;
    }
  };
  const _mergeIndices = (geometry, geometries) => {
    let indexCount = 0;
    for (const g of geometries) {
      indexCount += g.index.count;
    }
    const indexData = new Uint32Array(indexCount);

    let positionOffset = 0;
    let indexOffset = 0;
    for (const g of geometries) {
      const srcIndexData = g.index.array;
      for (let i = 0; i < srcIndexData.length; i++) {
        indexData[indexOffset++] = srcIndexData[i] + positionOffset;
      }
      positionOffset += g.attributes.position.count;
    }
    geometry.setIndex(new THREE.BufferAttribute(indexData, 1));
  };
  const _remapGeometryUvs = (geometry, geometries) => {
    if (atlas) {
      let uvIndex = 0;
      const geometryUvOffsets = geometries.map(g => {
        const start = uvIndex;
        const count = g.attributes.uv.count;
        uvIndex += count;
        return {
          start,
          count,
        };
      });

      const canvasSize = Math.min(atlas.width, textureSize);
      const canvasScale = canvasSize / atlas.width;
      atlas.bins.forEach(bin => {
        bin.rects.forEach(rect => {
          const {
            x,
            y,
            width: w,
            height: h,
            data: {index},
          } = rect;

          if (w > 0 && h > 0) {
            const {start, count} = geometryUvOffsets[index];

            const tx = x * canvasScale;
            const ty = y * canvasScale;
            const tw = w * canvasScale;
            const th = h * canvasScale;

            for (let i = 0; i < count; i++) {
              const uvIndex = start + i;

              localVector2D.fromArray(
                geometry.attributes.uv.array,
                uvIndex * 2,
              );
              modUv(localVector2D);
              localVector2D
                .multiply(localVector2D2.set(tw / canvasSize, th / canvasSize))
                .add(localVector2D2.set(tx / canvasSize, ty / canvasSize));
              localVector2D.toArray(geometry.attributes.uv.array, uvIndex * 2);
            }
          }
        });
      });
    }
  };
  const _mergeGeometries = geometries => {
    const geometry = new THREE.BufferGeometry();
    geometry.morphTargetsRelative = true;

    _forceGeometriesAttributeLayouts(attributeLayouts, geometries);
    _mergeAttributes(geometry, geometries, attributeLayouts);
    _mergeMorphAttributes(geometry, geometries, morphAttributeLayouts);
    _mergeIndices(geometry, geometries);
    _remapGeometryUvs(geometry, geometries);

    return geometry;
  };
  const geometry = _mergeGeometries(geometries);
  // console.log('got geometry', geometry);

  const _makeAtlasTextures = atlasImages => {
    const _makeAtlasTexture = atlasImage => {
      const originalTexture = originalTextures.get(atlasImage);

      const t = new THREE.Texture(atlasImage);
      t.minFilter = originalTexture.minFilter;
      t.magFilter = originalTexture.magFilter;
      t.wrapS = originalTexture.wrapS;
      t.wrapT = originalTexture.wrapT;
      t.mapping = originalTexture.mapping;
      // t.encoding = originalTexture.encoding;

      t.flipY = false;
      t.needsUpdate = true;

      return t;
    };

    const result = {};
    const textureMap = new Map(); // cache to alias identical textures
    for (const textureType of textureTypes) {
      const atlasImage = atlasImages[textureType];

      if (atlasImage) {
        let atlasTexture = textureMap.get(atlasImage.key);
        if (atlasTexture === undefined) {
          // cache miss
          atlasTexture = _makeAtlasTexture(atlasImage);
          textureMap.set(atlasImage.key, atlasTexture);
        }
        result[textureType] = atlasTexture;
      } else {
        result[textureType] = null;
      }
    }
    return result;
  };
  const atlasTextures = atlasImages ? _makeAtlasTextures(atlasImages) : null;

  return {
    atlas,
    atlasImages,
    attributeLayouts,
    morphAttributeLayouts,
    geometry,
    atlasTextures,
  };
};