mesa: new _mesa_prepare_mipmap_levels() function for mipmap generation

Simplifies the loops in generate_mipmap_uncompressed() and
generate_mipmap_compressed().  Will be used in the state tracker too.
Could probably be used in the meta code.  If so, some additional
clean-ups can be done after that.

v2: use unsigned types instead of GLuint, per Ian

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

src/mesa/main/mipmap.c

@@ -1872,6 +1872,49 @@ _mesa_prepare_mipmap_level(struct gl_context *ctx,
 }
 
 
+/**
+ * Prepare all mipmap levels beyond 'baseLevel' for mipmap generation.
+ * When finished, all the gl_texture_image structures for the smaller
+ * mipmap levels will be consistent with the base level (in terms of
+ * dimensions, format, etc).
+ */
+void
+_mesa_prepare_mipmap_levels(struct gl_context *ctx,
+                            struct gl_texture_object *texObj,
+                            unsigned baseLevel, unsigned maxLevel)
+{
+   const struct gl_texture_image *baseImage =
+      _mesa_select_tex_image(texObj, texObj->Target, baseLevel);
+   const GLint border = 0;
+   GLint width = baseImage->Width;
+   GLint height = baseImage->Height;
+   GLint depth = baseImage->Depth;
+   const GLenum intFormat = baseImage->InternalFormat;
+   const mesa_format texFormat = baseImage->TexFormat;
+   GLint newWidth, newHeight, newDepth;
+
+   /* Prepare baseLevel + 1, baseLevel + 2, ... */
+   for (unsigned level = baseLevel + 1; level <= maxLevel; level++) {
+      if (!_mesa_next_mipmap_level_size(texObj->Target, border,
+                                        width, height, depth,
+                                        &newWidth, &newHeight, &newDepth)) {
+         /* all done */
+         break;
+      }
+
+      if (!_mesa_prepare_mipmap_level(ctx, texObj, level,
+                                      newWidth, newHeight, newDepth,
+                                      border, intFormat, texFormat)) {
+         break;
+      }
+
+      width = newWidth;
+      height = newHeight;
+      depth = newDepth;
+   }
+}
+
+
 static void
 generate_mipmap_uncompressed(struct gl_context *ctx, GLenum target,
 			     struct gl_texture_object *texObj,
@@ -1892,7 +1935,6 @@ generate_mipmap_uncompressed(struct gl_context *ctx, GLenum target,
       GLint dstWidth, dstHeight, dstDepth;
       GLint border;
       GLint slice;
-      GLboolean nextLevel;
       GLubyte **srcMaps, **dstMaps;
       GLboolean success = GL_TRUE;
 
@@ -1904,22 +1946,14 @@ generate_mipmap_uncompressed(struct gl_context *ctx, GLenum target,
       srcDepth = srcImage->Depth;
       border = srcImage->Border;
 
-      nextLevel = _mesa_next_mipmap_level_size(target, border,
-                                         srcWidth, srcHeight, srcDepth,
-                                         &dstWidth, &dstHeight, &dstDepth);
-      if (!nextLevel)
-         return;
-
-      if (!_mesa_prepare_mipmap_level(ctx, texObj, level + 1,
-                                      dstWidth, dstHeight, dstDepth,
-                                      border, srcImage->InternalFormat,
-                                      srcImage->TexFormat)) {
-         return;
-      }
-
       /* get dest gl_texture_image */
       dstImage = _mesa_select_tex_image(texObj, target, level + 1);
-      assert(dstImage);
+      if (!dstImage) {
+         break;
+      }
+      dstWidth = dstImage->Width;
+      dstHeight = dstImage->Height;
+      dstDepth = dstImage->Depth;
 
       if (target == GL_TEXTURE_1D_ARRAY) {
 	 srcDepth = srcHeight;
@@ -2087,7 +2121,6 @@ generate_mipmap_compressed(struct gl_context *ctx, GLenum target,
       GLint srcWidth, srcHeight, srcDepth;
       GLint dstWidth, dstHeight, dstDepth;
       GLint border;
-      GLboolean nextLevel;
       GLuint temp_dst_row_stride, temp_dst_img_stride; /* in bytes */
       GLint i;
 
@@ -2099,23 +2132,14 @@ generate_mipmap_compressed(struct gl_context *ctx, GLenum target,
       srcDepth = srcImage->Depth;
       border = srcImage->Border;
 
-      nextLevel = _mesa_next_mipmap_level_size(target, border,
-                                         srcWidth, srcHeight, srcDepth,
-                                         &dstWidth, &dstHeight, &dstDepth);
-      if (!nextLevel)
-	 goto end;
-
-      if (!_mesa_prepare_mipmap_level(ctx, texObj, level + 1,
-                                      dstWidth, dstHeight, dstDepth,
-                                      border, srcImage->InternalFormat,
-                                      srcImage->TexFormat)) {
-         /* all done */
-         goto end;
-      }
-
       /* get dest gl_texture_image */
       dstImage = _mesa_select_tex_image(texObj, target, level + 1);
-      assert(dstImage);
+      if (!dstImage) {
+         break;
+      }
+      dstWidth = dstImage->Width;
+      dstHeight = dstImage->Height;
+      dstDepth = dstImage->Depth;
 
       /* Compute dst image strides and alloc memory on first iteration */
       temp_dst_row_stride = _mesa_format_row_stride(temp_format, dstWidth);
@@ -2194,6 +2218,8 @@ _mesa_generate_mipmap(struct gl_context *ctx, GLenum target,
 
    maxLevel = MIN2(maxLevel, texObj->MaxLevel);
 
+   _mesa_prepare_mipmap_levels(ctx, texObj, texObj->BaseLevel, maxLevel);
+
    if (_mesa_is_format_compressed(srcImage->TexFormat)) {
       generate_mipmap_compressed(ctx, target, texObj, srcImage, maxLevel);
    } else {

src/mesa/main/mipmap.h

@@ -47,6 +47,11 @@ _mesa_prepare_mipmap_level(struct gl_context *ctx,
                            GLsizei width, GLsizei height, GLsizei depth,
                            GLsizei border, GLenum intFormat, mesa_format format);
 
+void
+_mesa_prepare_mipmap_levels(struct gl_context *ctx,
+                            struct gl_texture_object *texObj,
+                            unsigned baseLevel, unsigned maxLevel);
+
 extern void
 _mesa_generate_mipmap(struct gl_context *ctx, GLenum target,
                       struct gl_texture_object *texObj);