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