mipmap.c

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

      /* allocate storage for uncompressed GL_RGB or GL_RGBA images */
      size = _mesa_bytes_per_pixel(srcImage->_BaseFormat, CHAN_TYPE)
         * srcImage->Width * srcImage->Height * srcImage->Depth + 20;
      /* 20 extra bytes, just be safe when calling last FetchTexel */
      srcData = (GLubyte *) _mesa_malloc(size);
      if (!srcData) {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "generate mipmaps");
         return;
      }
      dstData = (GLubyte *) _mesa_malloc(size / 2);  /* 1/4 would probably be OK */
      if (!dstData) {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "generate mipmaps");
         _mesa_free((void *) srcData);
         return;
      }

      /* decompress base image here */
      dst = (GLchan *) srcData;
      for (row = 0; row < srcImage->Height; row++) {
         GLuint col;
         for (col = 0; col < srcImage->Width; col++) {
            srcImage->FetchTexelc(srcImage, col, row, 0, dst);
            dst += components;
         }
      }
   }
   else {
      /* uncompressed */
      convertFormat = srcImage->TexFormat;
   }

   for (level = texObj->BaseLevel; level < texObj->MaxLevel
           && level < maxLevels - 1; level++) {
      /* generate image[level+1] from image[level] */
      const struct gl_texture_image *srcImage;
      struct gl_texture_image *dstImage;
      GLint srcWidth, srcHeight, srcDepth;
      GLint dstWidth, dstHeight, dstDepth;
      GLint border, bytesPerTexel;

      /* get src image parameters */
      srcImage = _mesa_select_tex_image(ctx, texObj, target, level);
      ASSERT(srcImage);
      srcWidth = srcImage->Width;
      srcHeight = srcImage->Height;
      srcDepth = srcImage->Depth;
      border = srcImage->Border;

      /* compute next (level+1) image size */
      if (srcWidth - 2 * border > 1) {
         dstWidth = (srcWidth - 2 * border) / 2 + 2 * border;
      }
      else {
         dstWidth = srcWidth; /* can't go smaller */
      }
      if ((srcHeight - 2 * border > 1) && 
          (texObj->Target != GL_TEXTURE_1D_ARRAY_EXT)) {
         dstHeight = (srcHeight - 2 * border) / 2 + 2 * border;
      }
      else {
         dstHeight = srcHeight; /* can't go smaller */
      }
      if ((srcDepth - 2 * border > 1) &&
               (texObj->Target != GL_TEXTURE_2D_ARRAY_EXT)) {
         dstDepth = (srcDepth - 2 * border) / 2 + 2 * border;
      }
      else {
         dstDepth = srcDepth; /* can't go smaller */
      }

      if (dstWidth == srcWidth &&
          dstHeight == srcHeight &&
          dstDepth == srcDepth) {
         /* all done */
         if (srcImage->IsCompressed) {
            _mesa_free((void *) srcData);
            _mesa_free(dstData);
         }
         return;
      }

      /* get dest gl_texture_image */
      dstImage = _mesa_get_tex_image(ctx, texObj, target, level + 1);
      if (!dstImage) {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "generating mipmaps");
         return;
      }

      if (dstImage->ImageOffsets)
         _mesa_free(dstImage->ImageOffsets);

      /* Free old image data */
      if (dstImage->Data)
         ctx->Driver.FreeTexImageData(ctx, dstImage);

      /* initialize new image */
      _mesa_init_teximage_fields(ctx, target, dstImage, dstWidth, dstHeight,
                                 dstDepth, border, srcImage->InternalFormat);
      dstImage->DriverData = NULL;
      dstImage->TexFormat = srcImage->TexFormat;
      dstImage->FetchTexelc = srcImage->FetchTexelc;
      dstImage->FetchTexelf = srcImage->FetchTexelf;
      dstImage->IsCompressed = srcImage->IsCompressed;
      if (dstImage->IsCompressed) {
         dstImage->CompressedSize
            = ctx->Driver.CompressedTextureSize(ctx, dstImage->Width,
                                              dstImage->Height,
                                              dstImage->Depth,
                                              dstImage->TexFormat->MesaFormat);
         ASSERT(dstImage->CompressedSize > 0);
      }

      ASSERT(dstImage->TexFormat);
      ASSERT(dstImage->FetchTexelc);
      ASSERT(dstImage->FetchTexelf);

      /* Alloc new teximage data buffer.
       * Setup src and dest data pointers.
       */
      if (dstImage->IsCompressed) {
         dstImage->Data = _mesa_alloc_texmemory(dstImage->CompressedSize);
         if (!dstImage->Data) {
            _mesa_error(ctx, GL_OUT_OF_MEMORY, "generating mipmaps");
            return;
         }
         /* srcData and dstData are already set */
         ASSERT(srcData);
         ASSERT(dstData);
      }
      else {
         bytesPerTexel = dstImage->TexFormat->TexelBytes;
         ASSERT(dstWidth * dstHeight * dstDepth * bytesPerTexel > 0);
         dstImage->Data = _mesa_alloc_texmemory(dstWidth * dstHeight
                                                * dstDepth * bytesPerTexel);
         if (!dstImage->Data) {
            _mesa_error(ctx, GL_OUT_OF_MEMORY, "generating mipmaps");
            return;
         }
         srcData = (const GLubyte *) srcImage->Data;
         dstData = (GLubyte *) dstImage->Data;
      }

      /*
       * We use simple 2x2 averaging to compute the next mipmap level.
       */
      switch (target) {
         case GL_TEXTURE_1D:
            make_1d_mipmap(convertFormat, border,
                           srcWidth, srcData,
                           dstWidth, dstData);
            break;
         case GL_TEXTURE_2D:
         case GL_TEXTURE_CUBE_MAP_POSITIVE_X_ARB:
         case GL_TEXTURE_CUBE_MAP_NEGATIVE_X_ARB:
         case GL_TEXTURE_CUBE_MAP_POSITIVE_Y_ARB:
         case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y_ARB:
         case GL_TEXTURE_CUBE_MAP_POSITIVE_Z_ARB:
         case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z_ARB:
            make_2d_mipmap(convertFormat, border,
                           srcWidth, srcHeight, srcData, srcImage->RowStride,
                           dstWidth, dstHeight, dstData, dstImage->RowStride);
            break;
         case GL_TEXTURE_3D:
            make_3d_mipmap(convertFormat, border,
                           srcWidth, srcHeight, srcDepth,
			   srcData, srcImage->RowStride,
                           dstWidth, dstHeight, dstDepth,
			   dstData, dstImage->RowStride);
            break;
         case GL_TEXTURE_1D_ARRAY_EXT:
            make_1d_stack_mipmap(convertFormat, border,
                                 srcWidth, srcData, srcImage->RowStride,
                                 dstWidth, dstHeight,
				 dstData, dstImage->RowStride);
            break;
         case GL_TEXTURE_2D_ARRAY_EXT:
            make_2d_stack_mipmap(convertFormat, border,
                                 srcWidth, srcHeight,
				 srcData, srcImage->RowStride,
                                 dstWidth, dstHeight,
				 dstDepth, dstData, dstImage->RowStride);
            break;
         case GL_TEXTURE_RECTANGLE_NV:
            /* no mipmaps, do nothing */
            break;
         default:
            _mesa_problem(ctx, "bad dimensions in _mesa_generate_mipmaps");
            return;
      }

      if (dstImage->IsCompressed) {
         GLubyte *temp;
         /* compress image from dstData into dstImage->Data */
         const GLenum srcFormat = convertFormat->BaseFormat;
         GLint dstRowStride
            = _mesa_compressed_row_stride(dstImage->TexFormat->MesaFormat, dstWidth);
         ASSERT(srcFormat == GL_RGB || srcFormat == GL_RGBA);
         dstImage->TexFormat->StoreImage(ctx, 2, dstImage->_BaseFormat,
                                         dstImage->TexFormat,
                                         dstImage->Data,
                                         0, 0, 0, /* dstX/Y/Zoffset */
                                         dstRowStride, 0, /* strides */
                                         dstWidth, dstHeight, 1, /* size */
                                         srcFormat, CHAN_TYPE,
                                         dstData, /* src data, actually */
                                         &ctx->DefaultPacking);
         /* swap src and dest pointers */
         temp = (GLubyte *) srcData;
         srcData = dstData;
         dstData = temp;
      }

   } /* loop over mipmap levels */
}


/**
 * Helper function for drivers which need to rescale texture images to
 * certain aspect ratios.
 * Nearest filtering only (for broken hardware that can't support
 * all aspect ratios).  This can be made a lot faster, but I don't
 * really care enough...
 */
void
_mesa_rescale_teximage2d(GLuint bytesPerPixel,
			 GLuint srcStrideInPixels,
			 GLuint dstRowStride,
			 GLint srcWidth, GLint srcHeight,
			 GLint dstWidth, GLint dstHeight,
			 const GLvoid *srcImage, GLvoid *dstImage)
{
   GLint row, col;

#define INNER_LOOP( TYPE, HOP, WOP )					\
   for ( row = 0 ; row < dstHeight ; row++ ) {				\
      GLint srcRow = row HOP hScale;					\
      for ( col = 0 ; col < dstWidth ; col++ ) {			\
	 GLint srcCol = col WOP wScale;					\
	 dst[col] = src[srcRow * srcStrideInPixels + srcCol];		\
      }									\
      dst = (TYPE *) ((GLubyte *) dst + dstRowStride);			\
   }									\

#define RESCALE_IMAGE( TYPE )						\
do {									\
   const TYPE *src = (const TYPE *)srcImage;				\
   TYPE *dst = (TYPE *)dstImage;					\
									\
   if ( srcHeight < dstHeight ) {					\
      const GLint hScale = dstHeight / srcHeight;			\
      if ( srcWidth < dstWidth ) {					\
	 const GLint wScale = dstWidth / srcWidth;			\
	 INNER_LOOP( TYPE, /, / );					\
      }									\
      else {								\
	 const GLint wScale = srcWidth / dstWidth;			\
	 INNER_LOOP( TYPE, /, * );					\
      }									\
   }									\
   else {								\
      const GLint hScale = srcHeight / dstHeight;			\
      if ( srcWidth < dstWidth ) {					\
	 const GLint wScale = dstWidth / srcWidth;			\
	 INNER_LOOP( TYPE, *, / );					\
      }									\
      else {								\
	 const GLint wScale = srcWidth / dstWidth;			\
	 INNER_LOOP( TYPE, *, * );					\
      }									\
   }									\
} while (0)

   switch ( bytesPerPixel ) {
   case 4:
      RESCALE_IMAGE( GLuint );
      break;

   case 2:
      RESCALE_IMAGE( GLushort );
      break;

   case 1:
      RESCALE_IMAGE( GLubyte );
      break;
   default:
      _mesa_problem(NULL,"unexpected bytes/pixel in _mesa_rescale_teximage2d");
   }
}


/**
 * Upscale an image by replication, not (typical) stretching.
 * We use this when the image width or height is less than a
 * certain size (4, 8) and we need to upscale an image.
 */
void
_mesa_upscale_teximage2d(GLsizei inWidth, GLsizei inHeight,
                         GLsizei outWidth, GLsizei outHeight,
                         GLint comps, const GLchan *src, GLint srcRowStride,
                         GLchan *dest )
{
   GLint i, j, k;

   ASSERT(outWidth >= inWidth);
   ASSERT(outHeight >= inHeight);
#if 0
   ASSERT(inWidth == 1 || inWidth == 2 || inHeight == 1 || inHeight == 2);
   ASSERT((outWidth & 3) == 0);
   ASSERT((outHeight & 3) == 0);
#endif

   for (i = 0; i < outHeight; i++) {
      const GLint ii = i % inHeight;
      for (j = 0; j < outWidth; j++) {
         const GLint jj = j % inWidth;
         for (k = 0; k < comps; k++) {
            dest[(i * outWidth + j) * comps + k]
               = src[ii * srcRowStride + jj * comps + k];
         }
      }
   }
}