mipmap.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

   bytesPerDstImage = dstWidth * dstHeight * bpt;

   bytesPerSrcRow = srcWidth * bpt;
   bytesPerDstRow = dstWidth * bpt;

   /* Offset between adjacent src images to be averaged together */
   srcImageOffset = (srcDepth == dstDepth) ? 0 : bytesPerSrcImage;

   /* Offset between adjacent src rows to be averaged together */
   srcRowOffset = (srcHeight == dstHeight) ? 0 : srcWidth * bpt;

   /*
    * Need to average together up to 8 src pixels for each dest pixel.
    * Break that down into 3 operations:
    *   1. take two rows from source image and average them together.
    *   2. take two rows from next source image and average them together.
    *   3. take the two averaged rows and average them for the final dst row.
    */

   /*
   _mesa_printf("mip3d %d x %d x %d  ->  %d x %d x %d\n",
          srcWidth, srcHeight, srcDepth, dstWidth, dstHeight, dstDepth);
   */

   for (img = 0; img < dstDepthNB; img++) {
      /* first source image pointer, skipping border */
      const GLubyte *imgSrcA = srcPtr
         + (bytesPerSrcImage + bytesPerSrcRow + border) * bpt * border
         + img * (bytesPerSrcImage + srcImageOffset);
      /* second source image pointer, skipping border */
      const GLubyte *imgSrcB = imgSrcA + srcImageOffset;
      /* address of the dest image, skipping border */
      GLubyte *imgDst = dstPtr
         + (bytesPerDstImage + bytesPerDstRow + border) * bpt * border
         + img * bytesPerDstImage;

      /* setup the four source row pointers and the dest row pointer */
      const GLubyte *srcImgARowA = imgSrcA;
      const GLubyte *srcImgARowB = imgSrcA + srcRowOffset;
      const GLubyte *srcImgBRowA = imgSrcB;
      const GLubyte *srcImgBRowB = imgSrcB + srcRowOffset;
      GLubyte *dstImgRow = imgDst;

      for (row = 0; row < dstHeightNB; row++) {
         /* Average together two rows from first src image */
         do_row(format, srcWidthNB, srcImgARowA, srcImgARowB,
                srcWidthNB, tmpRowA);
         /* Average together two rows from second src image */
         do_row(format, srcWidthNB, srcImgBRowA, srcImgBRowB,
                srcWidthNB, tmpRowB);
         /* Average together the temp rows to make the final row */
         do_row(format, srcWidthNB, tmpRowA, tmpRowB,
                dstWidthNB, dstImgRow);
         /* advance to next rows */
         srcImgARowA += bytesPerSrcRow + srcRowOffset;
         srcImgARowB += bytesPerSrcRow + srcRowOffset;
         srcImgBRowA += bytesPerSrcRow + srcRowOffset;
         srcImgBRowB += bytesPerSrcRow + srcRowOffset;
         dstImgRow += bytesPerDstRow;
      }
   }

   _mesa_free(tmpRowA);
   _mesa_free(tmpRowB);

   /* Luckily we can leverage the make_2d_mipmap() function here! */
   if (border > 0) {
      /* do front border image */
      make_2d_mipmap(format, 1, srcWidth, srcHeight, srcPtr, srcRowStride,
                     dstWidth, dstHeight, dstPtr, dstRowStride);
      /* do back border image */
      make_2d_mipmap(format, 1, srcWidth, srcHeight,
                     srcPtr + bytesPerSrcImage * (srcDepth - 1), srcRowStride,
                     dstWidth, dstHeight,
                     dstPtr + bytesPerDstImage * (dstDepth - 1), dstRowStride);
      /* do four remaining border edges that span the image slices */
      if (srcDepth == dstDepth) {
         /* just copy border pixels from src to dst */
         for (img = 0; img < dstDepthNB; img++) {
            const GLubyte *src;
            GLubyte *dst;

            /* do border along [img][row=0][col=0] */
            src = srcPtr + (img + 1) * bytesPerSrcImage;
            dst = dstPtr + (img + 1) * bytesPerDstImage;
            MEMCPY(dst, src, bpt);

            /* do border along [img][row=dstHeight-1][col=0] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (srcHeight - 1) * bytesPerSrcRow;
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (dstHeight - 1) * bytesPerDstRow;
            MEMCPY(dst, src, bpt);

            /* do border along [img][row=0][col=dstWidth-1] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (srcWidth - 1) * bpt;
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (dstWidth - 1) * bpt;
            MEMCPY(dst, src, bpt);

            /* do border along [img][row=dstHeight-1][col=dstWidth-1] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (bytesPerSrcImage - bpt);
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (bytesPerDstImage - bpt);
            MEMCPY(dst, src, bpt);
         }
      }
      else {
         /* average border pixels from adjacent src image pairs */
         ASSERT(srcDepthNB == 2 * dstDepthNB);
         for (img = 0; img < dstDepthNB; img++) {
            const GLubyte *src;
            GLubyte *dst;

            /* do border along [img][row=0][col=0] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage;
            dst = dstPtr + (img + 1) * bytesPerDstImage;
            do_row(format, 1, src, src + srcImageOffset, 1, dst);

            /* do border along [img][row=dstHeight-1][col=0] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (srcHeight - 1) * bytesPerSrcRow;
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (dstHeight - 1) * bytesPerDstRow;
            do_row(format, 1, src, src + srcImageOffset, 1, dst);

            /* do border along [img][row=0][col=dstWidth-1] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (srcWidth - 1) * bpt;
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (dstWidth - 1) * bpt;
            do_row(format, 1, src, src + srcImageOffset, 1, dst);

            /* do border along [img][row=dstHeight-1][col=dstWidth-1] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (bytesPerSrcImage - bpt);
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (bytesPerDstImage - bpt);
            do_row(format, 1, src, src + srcImageOffset, 1, dst);
         }
      }
   }
}


static void
make_1d_stack_mipmap(const struct gl_texture_format *format, GLint border,
                     GLint srcWidth, const GLubyte *srcPtr, GLuint srcRowStride,
                     GLint dstWidth, GLint dstHeight,
		     GLubyte *dstPtr, GLuint dstRowStride )
{
   const GLint bpt = format->TexelBytes;
   const GLint srcWidthNB = srcWidth - 2 * border;  /* sizes w/out border */
   const GLint dstWidthNB = dstWidth - 2 * border;
   const GLint dstHeightNB = dstHeight - 2 * border;
   const GLint srcRowBytes = bpt * srcRowStride;
   const GLint dstRowBytes = bpt * dstRowStride;
   const GLubyte *src;
   GLubyte *dst;
   GLint row;

   /* Compute src and dst pointers, skipping any border */
   src = srcPtr + border * ((srcWidth + 1) * bpt);
   dst = dstPtr + border * ((dstWidth + 1) * bpt);

   for (row = 0; row < dstHeightNB; row++) {
      do_row(format, srcWidthNB, src, src,
             dstWidthNB, dst);
      src += srcRowBytes;
      dst += dstRowBytes;
   }

   if (border) {
      /* copy left-most pixel from source */
      MEMCPY(dstPtr, srcPtr, bpt);
      /* copy right-most pixel from source */
      MEMCPY(dstPtr + (dstWidth - 1) * bpt,
             srcPtr + (srcWidth - 1) * bpt,
             bpt);
   }
}


/**
 * \bugs
 * There is quite a bit of refactoring that could be done with this function
 * and \c make_2d_mipmap.
 */
static void
make_2d_stack_mipmap(const struct gl_texture_format *format, GLint border,
                     GLint srcWidth, GLint srcHeight,
		     const GLubyte *srcPtr, GLint srcRowStride,
                     GLint dstWidth, GLint dstHeight, GLint dstDepth,
                     GLubyte *dstPtr, GLint dstRowStride)
{
   const GLint bpt = format->TexelBytes;
   const GLint srcWidthNB = srcWidth - 2 * border;  /* sizes w/out border */
   const GLint dstWidthNB = dstWidth - 2 * border;
   const GLint dstHeightNB = dstHeight - 2 * border;
   const GLint dstDepthNB = dstDepth - 2 * border;
   const GLint srcRowBytes = bpt * srcRowStride;
   const GLint dstRowBytes = bpt * dstRowStride;
   const GLubyte *srcA, *srcB;
   GLubyte *dst;
   GLint layer;
   GLint row;

   /* Compute src and dst pointers, skipping any border */
   srcA = srcPtr + border * ((srcWidth + 1) * bpt);
   if (srcHeight > 1) 
      srcB = srcA + srcRowBytes;
   else
      srcB = srcA;
   dst = dstPtr + border * ((dstWidth + 1) * bpt);

   for (layer = 0; layer < dstDepthNB; layer++) {
      for (row = 0; row < dstHeightNB; row++) {
         do_row(format, srcWidthNB, srcA, srcB,
                dstWidthNB, dst);
         srcA += 2 * srcRowBytes;
         srcB += 2 * srcRowBytes;
         dst += dstRowBytes;
      }

      /* This is ugly but probably won't be used much */
      if (border > 0) {
         /* fill in dest border */
         /* lower-left border pixel */
         MEMCPY(dstPtr, srcPtr, bpt);
         /* lower-right border pixel */
         MEMCPY(dstPtr + (dstWidth - 1) * bpt,
                srcPtr + (srcWidth - 1) * bpt, bpt);
         /* upper-left border pixel */
         MEMCPY(dstPtr + dstWidth * (dstHeight - 1) * bpt,
                srcPtr + srcWidth * (srcHeight - 1) * bpt, bpt);
         /* upper-right border pixel */
         MEMCPY(dstPtr + (dstWidth * dstHeight - 1) * bpt,
                srcPtr + (srcWidth * srcHeight - 1) * bpt, bpt);
         /* lower border */
         do_row(format, srcWidthNB,
                srcPtr + bpt,
                srcPtr + bpt,
                dstWidthNB, dstPtr + bpt);
         /* upper border */
         do_row(format, srcWidthNB,
                srcPtr + (srcWidth * (srcHeight - 1) + 1) * bpt,
                srcPtr + (srcWidth * (srcHeight - 1) + 1) * bpt,
                dstWidthNB,
                dstPtr + (dstWidth * (dstHeight - 1) + 1) * bpt);
         /* left and right borders */
         if (srcHeight == dstHeight) {
            /* copy border pixel from src to dst */
            for (row = 1; row < srcHeight; row++) {
               MEMCPY(dstPtr + dstWidth * row * bpt,
                      srcPtr + srcWidth * row * bpt, bpt);
               MEMCPY(dstPtr + (dstWidth * row + dstWidth - 1) * bpt,
                      srcPtr + (srcWidth * row + srcWidth - 1) * bpt, bpt);
            }
         }
         else {
            /* average two src pixels each dest pixel */
            for (row = 0; row < dstHeightNB; row += 2) {
               do_row(format, 1,
                      srcPtr + (srcWidth * (row * 2 + 1)) * bpt,
                      srcPtr + (srcWidth * (row * 2 + 2)) * bpt,
                      1, dstPtr + (dstWidth * row + 1) * bpt);
               do_row(format, 1,
                      srcPtr + (srcWidth * (row * 2 + 1) + srcWidth - 1) * bpt,
                      srcPtr + (srcWidth * (row * 2 + 2) + srcWidth - 1) * bpt,
                      1, dstPtr + (dstWidth * row + 1 + dstWidth - 1) * bpt);
            }
         }
      }
   }
}


/**
 * For GL_SGIX_generate_mipmap:
 * Generate a complete set of mipmaps from texObj's base-level image.
 * Stop at texObj's MaxLevel or when we get to the 1x1 texture.
 */
void
_mesa_generate_mipmap(GLcontext *ctx, GLenum target,
                      struct gl_texture_object *texObj)
{
   const struct gl_texture_image *srcImage;
   const struct gl_texture_format *convertFormat;
   const GLubyte *srcData = NULL;
   GLubyte *dstData = NULL;
   GLint level, maxLevels;

   ASSERT(texObj);
   /* XXX choose cube map face here??? */
   srcImage = texObj->Image[0][texObj->BaseLevel];
   ASSERT(srcImage);

   maxLevels = _mesa_max_texture_levels(ctx, texObj->Target);
   ASSERT(maxLevels > 0);  /* bad target */

   /* Find convertFormat - the format that do_row() will process */
   if (srcImage->IsCompressed) {
      /* setup for compressed textures */
      GLuint row;
      GLint  components, size;
      GLchan *dst;

      assert(texObj->Target == GL_TEXTURE_2D ||
             texObj->Target == GL_TEXTURE_CUBE_MAP_ARB);

      if (srcImage->_BaseFormat == GL_RGB) {
         convertFormat = &_mesa_texformat_rgb;
         components = 3;
      }
      else if (srcImage->_BaseFormat == GL_RGBA) {
         convertFormat = &_mesa_texformat_rgba;
         components = 4;
      }
      else {
         _mesa_problem(ctx, "bad srcImage->_BaseFormat in _mesa_generate_mipmaps");
         return;
      }