feat: texture mutation

src/core/blitzkrieg/readTexture.ts

@@ -1,14 +1,96 @@
 import sharp from 'sharp';
+import { Vector3Tuple } from 'three';
 import { readDVPLFile } from '../blitz/readDVPLFile';
 import { DdsStream } from '../streams/dds';
 
-export async function readTexture(path: string) {
+export enum TextureMutation {
+  Normal,
+  RoughnessMetallicness,
+  BaseColor,
+}
+
+type ReadTextureOptions =
+  | {
+      mutation: TextureMutation.Normal | TextureMutation.RoughnessMetallicness;
+    }
+  | {
+      mutation: TextureMutation.BaseColor;
+      /**
+       * Normalized between 0 and 1
+       */
+      baseColor: Vector3Tuple;
+    };
+
+export async function readTexture(path: string, options?: ReadTextureOptions) {
   const ddsTexturePath = path.replace('.tex', '.dx11.dds.dvpl');
   const decompressedDvpl = await readDVPLFile(ddsTexturePath);
   const stream = new DdsStream(decompressedDvpl);
-  const ddsRaw = await stream.dds();
+  const dds = await stream.dds();
+  const channels = 4 * dds.width * dds.height;
 
-  return await sharp(ddsRaw.data, { raw: ddsRaw }).png().toBuffer();
+  /**
+   * Red is always 255 and blue is always 0. Only alpha and green contain any
+   * sort of information.
+   */
+  switch (options?.mutation) {
+    case TextureMutation.Normal: {
+      for (let index = 0; index < channels; index += 4) {
+        let x = dds.data[index + 3] / 255;
+        let y = dds.data[index + 1] / 255;
+        let z = Math.sqrt(1 - x ** 2 - y ** 2);
+        const hypot = Math.sqrt(x ** 2 + y ** 2 + z ** 2);
+
+        if (isFinite(hypot)) {
+          x /= hypot;
+          y /= hypot;
+          z /= hypot;
+        }
+
+        dds.data[index] = Math.round(x * 255);
+        dds.data[index + 1] = Math.round(y * 255);
+        dds.data[index + 2] = Math.round(z * 255);
+        dds.data[index + 3] = 255;
+      }
+
+      break;
+    }
+
+    case TextureMutation.RoughnessMetallicness: {
+      for (let index = 0; index < channels; index += 4) {
+        const metallicness = dds.data[index + 1];
+        const roughness = dds.data[index + 3];
+
+        dds.data[index] = 0;
+        dds.data[index + 1] = roughness;
+        dds.data[index + 2] = metallicness;
+        dds.data[index + 3] = 255;
+      }
+
+      break;
+    }
+
+    case TextureMutation.BaseColor: {
+      for (let index = 0; index < channels; index += 4) {
+        const r = dds.data[index] / 255;
+        const g = dds.data[index + 1] / 255;
+        const b = dds.data[index + 2] / 255;
+        const a = dds.data[index + 3] / 255;
+        const inverseA = 1 - a;
+        const mixedR = a * r + inverseA * options.baseColor[0];
+        const mixedG = a * g + inverseA * options.baseColor[1];
+        const mixedB = a * b + inverseA * options.baseColor[2];
+
+        dds.data[index] = mixedR * 255;
+        dds.data[index + 1] = mixedG * 255;
+        dds.data[index + 2] = mixedB * 255;
+        dds.data[index + 3] = 255;
+      }
+
+      break;
+    }
+  }
+
+  return await sharp(dds.data, { raw: dds }).png().toBuffer();
 
   // const isDds = existsSync(ddsTexturePath);
   // const resolvedTexturePath = isDds