Unity使用 16bit 压缩 Texture 颜色能均匀过渡

下面是unity自带 16bit 图 的效果，可以看到颜色过度的很不均匀，占用内存 0.5M

  

如果调成 truecolor 后 颜色过渡很均匀，而内存却占到 1.1 M

  

讲图片 后缀名改成  .Dither.png  结尾后回到 unity，设置贴图格式为 Truecolor 后，颜色过渡也很均匀，而且内存只占了 0.5M

以下代码来至 keijiro 的 github：unity-dither4444

 using UnityEngine;
 using UnityEditor;
 using System.Collections;

 class TextureModifier : AssetPostprocessor
 {
     void OnPreprocessTexture()
     {
         var importer = (assetImporter as TextureImporter);

         importer.textureType = TextureImporterType.GUI;

         if (assetPath.EndsWith ("Dither.png")) {
             importer.textureFormat = TextureImporterFormat.RGBA32;
         }
     }

     void OnPostprocessTexture (Texture2D texture)
     {
         if (!assetPath.EndsWith ("Dither.png")) {
             return;
         }

         var texw = texture.width;
         var texh = texture.height;

         var pixels = texture.GetPixels ();
         var offs = ;

         var k1Per15 = 1.0f / 15.0f;
         var k1Per16 = 1.0f / 16.0f;
         var k3Per16 = 3.0f / 16.0f;
         var k5Per16 = 5.0f / 16.0f;
         var k7Per16 = 7.0f / 16.0f;

         for (var y = ; y < texh; y++) {
             for (var x = ; x < texw; x++) {
                 float a = pixels [offs].a;
                 float r = pixels [offs].r;
                 float g = pixels [offs].g;
                 float b = pixels [offs].b;

                 var a2 = Mathf.Clamp01 (Mathf.Floor (a * ) * k1Per15);
                 var r2 = Mathf.Clamp01 (Mathf.Floor (r * ) * k1Per15);
                 var g2 = Mathf.Clamp01 (Mathf.Floor (g * ) * k1Per15);
                 var b2 = Mathf.Clamp01 (Mathf.Floor (b * ) * k1Per15);

                 var ae = a - a2;
                 var re = r - r2;
                 var ge = g - g2;
                 var be = b - b2;

                 pixels [offs].a = a2;
                 pixels [offs].r = r2;
                 pixels [offs].g = g2;
                 pixels [offs].b = b2;

                 var n1 = offs + ;
                 var n2 = offs + texw - ;
                 var n3 = offs + texw;
                 var n4 = offs + texw + ;

                 if (x < texw - ) {
                     pixels [n1].a += ae * k7Per16;
                     pixels [n1].r += re * k7Per16;
                     pixels [n1].g += ge * k7Per16;
                     pixels [n1].b += be * k7Per16;
                 }

                 if (y < texh - ) {
                     pixels [n3].a += ae * k5Per16;
                     pixels [n3].r += re * k5Per16;
                     pixels [n3].g += ge * k5Per16;
                     pixels [n3].b += be * k5Per16;

                     if (x > ) {
                         pixels [n2].a += ae * k3Per16;
                         pixels [n2].r += re * k3Per16;
                         pixels [n2].g += ge * k3Per16;
                         pixels [n2].b += be * k3Per16;
                     }

                     if (x < texw - ) {
                         pixels [n4].a += ae * k1Per16;
                         pixels [n4].r += re * k1Per16;
                         pixels [n4].g += ge * k1Per16;
                         pixels [n4].b += be * k1Per16;
                     }
                 }

                 offs++;
             }
         }

         texture.SetPixels (pixels);
         EditorUtility.CompressTexture (texture, TextureFormat.RGBA4444, TextureCompressionQuality.Best);
     }
 }