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/**************************************************************************
*
* Copyright 2011 VMware, Inc.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
* IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
#include "util/u_debug.h"
#include "util/u_math.h"
#include "util/u_format.h"
#include "util/u_draw.h"
/**
* Returns the largest legal index value plus one for the current set
* of bound vertex buffers. Regardless of any other consideration,
* all vertex lookups need to be clamped to 0..max_index-1 to prevent
* an out-of-bound access.
*
* Note that if zero is returned it means that one or more buffers is
* too small to contain any valid vertex data.
*/
unsigned
util_draw_max_index(
const struct pipe_vertex_buffer *vertex_buffers,
const struct pipe_vertex_element *vertex_elements,
unsigned nr_vertex_elements,
const struct pipe_draw_info *info)
{
unsigned max_index;
unsigned i;
max_index = ~0U - 1;
for (i = 0; i < nr_vertex_elements; i++) {
const struct pipe_vertex_element *element =
&vertex_elements[i];
const struct pipe_vertex_buffer *buffer =
&vertex_buffers[element->vertex_buffer_index];
unsigned buffer_size;
const struct util_format_description *format_desc;
unsigned format_size;
if (!buffer->buffer) {
continue;
}
assert(buffer->buffer->height0 == 1);
assert(buffer->buffer->depth0 == 1);
buffer_size = buffer->buffer->width0;
format_desc = util_format_description(element->src_format);
assert(format_desc->block.width == 1);
assert(format_desc->block.height == 1);
assert(format_desc->block.bits % 8 == 0);
format_size = format_desc->block.bits/8;
if (buffer->buffer_offset >= buffer_size) {
/* buffer is too small */
return 0;
}
buffer_size -= buffer->buffer_offset;
if (element->src_offset >= buffer_size) {
/* buffer is too small */
return 0;
}
buffer_size -= element->src_offset;
if (format_size > buffer_size) {
/* buffer is too small */
return 0;
}
buffer_size -= format_size;
if (buffer->stride != 0) {
unsigned buffer_max_index;
buffer_max_index = buffer_size / buffer->stride;
if (element->instance_divisor == 0) {
/* Per-vertex data */
max_index = MIN2(max_index, buffer_max_index);
}
else {
/* Per-instance data. Simply make sure the state tracker didn't
* request more instances than those that fit in the buffer */
if ((info->start_instance + info->instance_count)/element->instance_divisor
> (buffer_max_index + 1)) {
/* FIXME: We really should stop thinking in terms of maximum
* indices/instances and simply start clamping against buffer
* size. */
debug_printf("%s: too many instances for vertex buffer\n",
__FUNCTION__);
return 0;
}
}
}
}
return max_index + 1;
}
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