Changed: Implemented GL_ScaleBufferNearest; a nearest neighbor image …

…scaling algorithm for use with tiny graphics (w*h < 16) rather than hq2x. The hq2x algorithm can do nothing to help graphics this small and better results can be obtained with the simple nearest neighbor algorithm.

doomsday/engine/portable/include/gl_tex.h

@@ -73,4 +73,7 @@ int             DrawRealPatch(byte* buffer, int texwidth, int texheight,
                               boolean checkForAlpha);
 boolean         ImageHasAlpha(image_t *image);
 void            GL_TranslatePatch(lumppatch_t* patch, byte* transTable);
+
+int             GL_PickSmartScaleMethod(int width, int height);
+void            GL_SmartFilter(int method, byte* in, byte* out, int width, int height);
 #endif

doomsday/engine/portable/src/gl_tex.c

@@ -1155,3 +1155,47 @@ byte *GL_ApplyColorKeying(byte *buf, uint pixelSize, uint width,
 
     return NULL;
 }
+
+void GL_ScaleBufferNearest(const byte* in, int width, int height,
+    byte* out, int outWidth, int outHeight, int comps)
+{
+    int ratioX = (int)(width << 16 ) / outWidth + 1;
+    int ratioY = (int)(height << 16) / outHeight + 1;
+    int i, j;
+
+    int shearY = 0;
+    for(i = 0; i < outHeight; ++i, shearY += ratioY)
+    {
+        int shearX = 0;
+        int shearY2 = (shearY >> 16) * width;
+        for(j = 0; j < outWidth; ++j, out += comps, shearX += ratioX)
+        {
+            int c, n = (shearY2 + (shearX >> 16)) * comps;
+            for(c = 0; c < comps; ++c, n++)
+                out[c] = in[n];
+        }
+    }
+}
+
+int GL_PickSmartScaleMethod(int width, int height)
+{
+    if(width >= MINTEXWIDTH && height >= MINTEXHEIGHT)
+        return 2; // hq2x
+    return 1; // nearest neighbor.
+}
+
+void GL_SmartFilter(int method, byte* in, byte* out, int width, int height)
+{
+    switch(method)
+    {
+    default: // linear interpolation.
+        GL_ScaleBuffer32(in, width, height, out, width*2, height*2, 4);
+        break;
+    case 1: // nearest neighbor.
+        GL_ScaleBufferNearest(in, width, height, out, width*2, height*2, 4);
+        break;
+    case 2: // hq2x
+        GL_SmartFilter2x(in, out, width, height, width * 8);
+        break;
+    };
+}

doomsday/engine/portable/src/gl_texmanager.c

@@ -574,7 +574,7 @@ DGLuint GL_UploadTexture2(texturecontent_t* content)
             alphaChannel = true;
         }
 
-        GL_SmartFilter2x(rgbaOriginal, filtered, width, height, width * 8);
+        GL_SmartFilter(GL_PickSmartScaleMethod(width, height), rgbaOriginal, filtered, width, height);
         width *= 2;
         height *= 2;
         noStretch = GL_OptimalSize(width, height, &levelWidth, &levelHeight, noStretch, generateMipmaps);
@@ -2618,6 +2618,7 @@ gltexture_inst_t* GLTexture_Prepare(gltexture_t* tex, void* context, byte* resul
 
             if(scaleSharp)
             {
+                int scaleMethod = GL_PickSmartScaleMethod(image.width, image.height);
                 int numpels = image.width * image.height;
                 byte* rgbaPixels = M_Malloc(numpels * 4 * 2);
                 byte* upscaledPixels = M_Malloc(numpels * 4 * 4);
@@ -2627,7 +2628,7 @@ gltexture_inst_t* GLTexture_Prepare(gltexture_t* tex, void* context, byte* resul
                 if(monochrome && (tex->type == GLT_DOOMPATCH || tex->type == GLT_SPRITE))
                     Desaturate(rgbaPixels, image.width, image.height, 4);
 
-                GL_SmartFilter2x(rgbaPixels, upscaledPixels, image.width, image.height, image.width * 8);
+                GL_SmartFilter(scaleMethod, rgbaPixels, upscaledPixels, image.width, image.height);
                 image.width *= 2;
                 image.height *= 2;
 
@@ -2770,7 +2771,7 @@ gltexture_inst_t* GLTexture_Prepare(gltexture_t* tex, void* context, byte* resul
                           image.pixelSize == 4 ? DGL_RGBA : DGL_LUMINANCE );
         }
 
-        if(tex->type == GLT_FLAT || tex->type == GLT_DOOMTEXTURE || tex->type == GLT_DOOMPATCH || tex->type == GLT_MASK)
+        if(tex->type == GLT_FLAT || tex->type == GLT_DOOMTEXTURE || tex->type == GLT_MASK)
             magFilter = glmode[texMagMode];
         else if(tex->type == GLT_SPRITE)
             magFilter = filterSprites ? GL_LINEAR : GL_NEAREST;