Add blit functions

Source/ConformalDecals/ConformalDecals.csproj

@@ -65,6 +65,7 @@
         <Compile Include="Properties\AssemblyInfo.cs" />
         <Compile Include="Util\Logging.cs" />
         <Compile Include="Util\OrientedBounds.cs" />
+        <Compile Include="Util\TextureUtils.cs" />
     </ItemGroup>
     <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
     <PropertyGroup>

Source/ConformalDecals/Util/TextureUtils.cs

@@ -0,0 +1,131 @@
+using UnityEngine;
+
+namespace ConformalDecals.Util {
+    public static class TextureUtils {
+        public static void BlitRect(
+            Texture2D src, Color32[] srcColors, Vector2Int srcPos,
+            Texture2D dst, Color32[] dstColors, Vector2Int dstPos,
+            Vector2Int size) {
+
+            if (srcPos.x < 0) {
+                size.x += srcPos.x;
+                dstPos.x -= srcPos.x;
+                srcPos.x = 0;
+            }
+
+            if (srcPos.y < 0) {
+                size.y += srcPos.y;
+                dstPos.y -= srcPos.y;
+                srcPos.y = 0;
+            }
+
+            if (dstPos.x < 0) {
+                size.x += dstPos.x;
+                srcPos.x -= dstPos.x;
+                dstPos.x = 0;
+            }
+
+            if (dstPos.y < 0) {
+                size.y += dstPos.y;
+                srcPos.y -= dstPos.y;
+                dstPos.y = 0;
+            }
+
+            if (srcPos.x + size.x > src.width) size.x = src.width - srcPos.x;
+            if (srcPos.y + size.y > src.height) size.y = src.height - srcPos.y;
+            if (dstPos.x + size.x > dst.width) size.x = dst.width - srcPos.x;
+            if (dstPos.y + size.y > dst.height) size.y = dst.height - srcPos.y;
+
+            if (size.x <= 0) return;
+            if (size.y <= 0) return;
+
+            int srcIndex = srcPos.x + srcPos.y * src.width;
+            int dstIndex = dstPos.x + dstPos.y * dst.width;
+
+            for (int dy = 0; dy < size.y; dy++) {
+
+                for (int dx = 0; dx < size.x; dx++) {
+                    dstColors[dstIndex + dx] = srcColors[srcIndex + dx];
+                }
+
+                srcIndex += src.width;
+                dstIndex += dst.width;
+            }
+        }
+
+        public static void BlitRectBilinear(
+            Texture2D src, Vector2Int srcPos, Vector2 srcSize,
+            Texture2D dst, Color32[] dstColors, Vector2Int dstPos, Vector2Int dstSize) {
+
+            var sizeRatio = dstSize / srcSize;
+
+            if (srcPos.x < 0) {
+                dstSize.x += (int) (srcPos.x * sizeRatio.x);
+                dstPos.x -= (int) (srcPos.x * sizeRatio.x);
+                srcSize.x += srcPos.x;
+                srcPos.x = 0;
+            }
+
+            if (srcPos.y < 0) {
+                dstSize.y += (int) (srcPos.y * sizeRatio.y);
+                dstPos.y -= (int) (srcPos.y * sizeRatio.y);
+                srcSize.y += srcPos.y;
+                srcPos.y = 0;
+            }
+
+            if (dstPos.x < 0) {
+                srcSize.x += dstPos.x / sizeRatio.x;
+                srcPos.x -= (int) (dstPos.x / sizeRatio.x);
+                dstSize.x += dstPos.x;
+                dstPos.x = 0;
+            }
+
+            if (dstPos.y < 0) {
+                srcSize.y += dstPos.y / sizeRatio.y;
+                srcPos.y -= (int) (dstPos.y / sizeRatio.y);
+                dstSize.y += dstPos.y;
+                dstPos.y = 0;
+            }
+
+            if (srcPos.x + srcSize.x > src.width) {
+                srcSize.x = src.width - srcPos.x;
+                dstSize.x = (int) (srcSize.x * sizeRatio.x);
+            }
+
+            if (srcPos.y + srcSize.y > src.height) {
+                srcSize.y = src.height - srcPos.y;
+                dstSize.y = (int) (srcSize.y * sizeRatio.y);
+            }
+
+            if (dstPos.x + dstSize.x > dst.width) {
+                dstSize.x = dst.width - srcPos.x;
+                srcSize.x = (int) (dstSize.x / sizeRatio.x);
+            }
+
+            if (dstPos.y + dstSize.y > dst.height) {
+                dstSize.y = dst.height - srcPos.y;
+                srcSize.y = (int) (dstSize.y / sizeRatio.y);
+            }
+
+            var srcPixel = new Vector2(1.0f / src.width, 1.0f / src.height);
+
+            var srcStart = (srcPos * srcPixel) + (srcPixel / 2);
+            var srcStep = sizeRatio * srcPixel;
+
+            var srcY = srcStart.y;
+            int dstIndex = dstPos.x + dstPos.y * dst.width;
+
+            for (int dy = 0; dy < dstSize.y; dy++) {
+                var srcX = srcStart.x;
+
+                for (int dx = 0; dx < dstSize.x; dx++) {
+                    dstColors[dstIndex + dx] = src.GetPixelBilinear(srcX, srcY);
+                    srcX += srcStep.x;
+                }
+
+                srcY += srcStep.y;
+                dstIndex += dst.width;
+            }
+        }
+    }
+}