Subversion Repositories Kolibri OS

Rev

Go to most recent revision | Blame | Last modification | View Log | RSS feed

  1. /**************************************************************************
  2.  *
  3.  * Copyright 2011 VMware, Inc.
  4.  * All Rights Reserved.
  5.  *
  6.  * Permission is hereby granted, free of charge, to any person obtaining a
  7.  * copy of this software and associated documentation files (the
  8.  * "Software"), to deal in the Software without restriction, including
  9.  * without limitation the rights to use, copy, modify, merge, publish,
  10.  * distribute, sub license, and/or sell copies of the Software, and to
  11.  * permit persons to whom the Software is furnished to do so, subject to
  12.  * the following conditions:
  13.  *
  14.  * The above copyright notice and this permission notice (including the
  15.  * next paragraph) shall be included in all copies or substantial portions
  16.  * of the Software.
  17.  *
  18.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19.  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20.  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  21.  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
  22.  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  23.  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  24.  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25.  *
  26.  **************************************************************************/
  27.  
  28.  
  29. #include "util/u_debug.h"
  30. #include "util/u_math.h"
  31. #include "util/u_format.h"
  32. #include "util/u_draw.h"
  33.  
  34.  
  35. /**
  36.  * Returns the largest legal index value plus one for the current set
  37.  * of bound vertex buffers.  Regardless of any other consideration,
  38.  * all vertex lookups need to be clamped to 0..max_index-1 to prevent
  39.  * an out-of-bound access.
  40.  *
  41.  * Note that if zero is returned it means that one or more buffers is
  42.  * too small to contain any valid vertex data.
  43.  */
  44. unsigned
  45. util_draw_max_index(
  46.       const struct pipe_vertex_buffer *vertex_buffers,
  47.       const struct pipe_vertex_element *vertex_elements,
  48.       unsigned nr_vertex_elements,
  49.       const struct pipe_draw_info *info)
  50. {
  51.    unsigned max_index;
  52.    unsigned i;
  53.  
  54.    max_index = ~0U - 1;
  55.    for (i = 0; i < nr_vertex_elements; i++) {
  56.       const struct pipe_vertex_element *element =
  57.          &vertex_elements[i];
  58.       const struct pipe_vertex_buffer *buffer =
  59.          &vertex_buffers[element->vertex_buffer_index];
  60.       unsigned buffer_size;
  61.       const struct util_format_description *format_desc;
  62.       unsigned format_size;
  63.  
  64.       if (!buffer->buffer) {
  65.          continue;
  66.       }
  67.  
  68.       assert(buffer->buffer->height0 == 1);
  69.       assert(buffer->buffer->depth0 == 1);
  70.       buffer_size = buffer->buffer->width0;
  71.  
  72.       format_desc = util_format_description(element->src_format);
  73.       assert(format_desc->block.width == 1);
  74.       assert(format_desc->block.height == 1);
  75.       assert(format_desc->block.bits % 8 == 0);
  76.       format_size = format_desc->block.bits/8;
  77.  
  78.       if (buffer->buffer_offset >= buffer_size) {
  79.          /* buffer is too small */
  80.          return 0;
  81.       }
  82.  
  83.       buffer_size -= buffer->buffer_offset;
  84.  
  85.       if (element->src_offset >= buffer_size) {
  86.          /* buffer is too small */
  87.          return 0;
  88.       }
  89.  
  90.       buffer_size -= element->src_offset;
  91.  
  92.       if (format_size > buffer_size) {
  93.          /* buffer is too small */
  94.          return 0;
  95.       }
  96.  
  97.       buffer_size -= format_size;
  98.  
  99.       if (buffer->stride != 0) {
  100.          unsigned buffer_max_index;
  101.  
  102.          buffer_max_index = buffer_size / buffer->stride;
  103.  
  104.          if (element->instance_divisor == 0) {
  105.             /* Per-vertex data */
  106.             max_index = MIN2(max_index, buffer_max_index);
  107.          }
  108.          else {
  109.             /* Per-instance data. Simply make sure the state tracker didn't
  110.              * request more instances than those that fit in the buffer */
  111.             if ((info->start_instance + info->instance_count)/element->instance_divisor
  112.                 > (buffer_max_index + 1)) {
  113.                /* FIXME: We really should stop thinking in terms of maximum
  114.                 * indices/instances and simply start clamping against buffer
  115.                 * size. */
  116.                debug_printf("%s: too many instances for vertex buffer\n",
  117.                             __FUNCTION__);
  118.                return 0;
  119.             }
  120.          }
  121.       }
  122.    }
  123.  
  124.    return max_index + 1;
  125. }
  126.