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/*
* Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
* All Rights Reserved.
*
* Copyright © 2012 Intel Corporation
*
* 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, sublicense,
* 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 NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS 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.
*
* Authors:
* Jordan Justen <jordan.l.justen@intel.com>
*
*/
#include "main/imports.h"
#include "main/bufferobj.h"
#include "main/macros.h"
#include "vbo.h"
#include "vbo_context.h"
#define UPDATE_MIN2(a, b) (a) = MIN2((a), (b))
#define UPDATE_MAX2(a, b) (a) = MAX2((a), (b))
/*
* Notes on primitive restart:
* The code below is used when the driver does not support primitive
* restart itself. (ctx->Const.PrimitiveRestartInSoftware == GL_TRUE)
*
* We map the index buffer, find the restart indexes, unmap
* the index buffer then draw the sub-primitives delineated by the restarts.
*
* A couple possible optimizations:
* 1. Save the list of sub-primitive (start, count) values in a list attached
* to the index buffer for re-use in subsequent draws. The list would be
* invalidated when the contents of the buffer changed.
* 2. If drawing triangle strips or quad strips, create a new index buffer
* that uses duplicated vertices to render the disjoint strips as one
* long strip. We'd have to be careful to avoid using too much memory
* for this.
*
* Finally, some apps might perform better if they don't use primitive restart
* at all rather than this fallback path. Set MESA_EXTENSION_OVERRIDE to
* "-GL_NV_primitive_restart" to test that.
*/
struct sub_primitive
{
GLuint start;
GLuint count;
GLuint min_index;
GLuint max_index;
};
/**
* Scan the elements array to find restart indexes. Return an array
* of struct sub_primitive to indicate how to draw the sub-primitives
* are delineated by the restart index.
*/
static struct sub_primitive *
find_sub_primitives(const void *elements, unsigned element_size,
unsigned start, unsigned end, unsigned restart_index,
unsigned *num_sub_prims)
{
const unsigned max_prims = end - start;
struct sub_primitive *sub_prims;
unsigned i, cur_start, cur_count;
GLuint scan_index;
unsigned scan_num;
sub_prims =
malloc(max_prims * sizeof(struct sub_primitive));
if (!sub_prims) {
*num_sub_prims = 0;
return NULL;
}
cur_start = start;
cur_count = 0;
scan_num = 0;
#define IB_INDEX_READ(TYPE, INDEX) (((const GL##TYPE *) elements)[INDEX])
#define SCAN_ELEMENTS(TYPE) \
sub_prims[scan_num].min_index = (GL##TYPE) 0xffffffff; \
sub_prims[scan_num].max_index = 0; \
for (i = start; i < end; i++) { \
scan_index = IB_INDEX_READ(TYPE, i); \
if (scan_index == restart_index) { \
if (cur_count > 0) { \
assert(scan_num < max_prims); \
sub_prims[scan_num].start = cur_start; \
sub_prims[scan_num].count = cur_count; \
scan_num++; \
sub_prims[scan_num].min_index = (GL##TYPE) 0xffffffff; \
sub_prims[scan_num].max_index = 0; \
} \
cur_start = i + 1; \
cur_count = 0; \
} \
else { \
UPDATE_MIN2(sub_prims[scan_num].min_index, scan_index); \
UPDATE_MAX2(sub_prims[scan_num].max_index, scan_index); \
cur_count++; \
} \
} \
if (cur_count > 0) { \
assert(scan_num < max_prims); \
sub_prims[scan_num].start = cur_start; \
sub_prims[scan_num].count = cur_count; \
scan_num++; \
}
switch (element_size) {
case 1:
SCAN_ELEMENTS(ubyte);
break;
case 2:
SCAN_ELEMENTS(ushort);
break;
case 4:
SCAN_ELEMENTS(uint);
break;
default:
assert(0 && "bad index_size in find_sub_primitives()");
}
#undef SCAN_ELEMENTS
*num_sub_prims = scan_num;
return sub_prims;
}
/**
* Handle primitive restart in software.
*
* This function breaks up calls into the driver so primitive restart
* support is not required in the driver.
*/
void
vbo_sw_primitive_restart(struct gl_context *ctx,
const struct _mesa_prim *prims,
GLuint nr_prims,
const struct _mesa_index_buffer *ib)
{
GLuint prim_num;
struct sub_primitive *sub_prims;
struct sub_primitive *sub_prim;
GLuint num_sub_prims;
GLuint sub_prim_num;
GLuint end_index;
GLuint sub_end_index;
GLuint restart_index = ctx->Array._RestartIndex;
struct _mesa_prim temp_prim;
struct vbo_context *vbo = vbo_context(ctx);
vbo_draw_func draw_prims_func = vbo->draw_prims;
GLboolean map_ib = ib->obj->Name && !ib->obj->Pointer;
void *ptr;
/* Find the sub-primitives. These are regions in the index buffer which
* are split based on the primitive restart index value.
*/
if (map_ib) {
ctx->Driver.MapBufferRange(ctx, 0, ib->obj->Size, GL_MAP_READ_BIT,
ib->obj);
}
ptr = ADD_POINTERS(ib->obj->Pointer, ib->ptr);
sub_prims = find_sub_primitives(ptr, vbo_sizeof_ib_type(ib->type),
0, ib->count, restart_index,
&num_sub_prims);
if (map_ib) {
ctx->Driver.UnmapBuffer(ctx, ib->obj);
}
/* Loop over the primitives, and use the located sub-primitives to draw
* each primitive with a break to implement each primitive restart.
*/
for (prim_num = 0; prim_num < nr_prims; prim_num++) {
end_index = prims[prim_num].start + prims[prim_num].count;
memcpy(&temp_prim, &prims[prim_num], sizeof (temp_prim));
/* Loop over the sub-primitives drawing sub-ranges of the primitive. */
for (sub_prim_num = 0; sub_prim_num < num_sub_prims; sub_prim_num++) {
sub_prim = &sub_prims[sub_prim_num];
sub_end_index = sub_prim->start + sub_prim->count;
if (prims[prim_num].start <= sub_prim->start) {
temp_prim.start = MAX2(prims[prim_num].start, sub_prim->start);
temp_prim.count = MIN2(sub_end_index, end_index) - temp_prim.start;
if ((temp_prim.start == sub_prim->start) &&
(temp_prim.count == sub_prim->count)) {
draw_prims_func(ctx, &temp_prim, 1, ib,
GL_TRUE, sub_prim->min_index, sub_prim->max_index,
NULL);
} else {
draw_prims_func(ctx, &temp_prim, 1, ib,
GL_FALSE, -1, -1,
NULL);
}
}
if (sub_end_index >= end_index) {
break;
}
}
}
free(sub_prims);
}
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