src/mesa/vbo/vbo_exec.c

   1 /*
   2  * Mesa 3-D graphics library
   3  *
   4  * Copyright (C) 1999-2005  Brian Paul   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 "Software"),
   8  * to deal in the Software without restriction, including without limitation
   9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10  * and/or sell copies of the Software, and to permit persons to whom the
  11  * Software is furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included
  14  * in all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  17  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  20  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  21  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  22  * OTHER DEALINGS IN THE SOFTWARE.
  23  *
  24  * Authors:
  25  *    Keith Whitwell <keithw@vmware.com>
  26  */
  27
  28
  29 #include "main/glheader.h"
  30 #include "main/mtypes.h"
  31 #include "main/vtxfmt.h"
  32 #include "vbo_context.h"
  33
  34
  35
  36 void
  37 vbo_exec_init(struct gl_context *ctx)
  38 {
  39    struct vbo_exec_context *exec = &vbo_context(ctx)->exec;
  40
  41    exec->ctx = ctx;
  42
  43    /* aelt_context should have been created by the caller */
  44    assert(ctx->aelt_context);
  45
  46    vbo_exec_vtx_init(exec);
  47
  48    ctx->Driver.NeedFlush = 0;
  49    ctx->Driver.CurrentExecPrimitive = PRIM_OUTSIDE_BEGIN_END;
  50
  51    /* The aelt_context state should still be dirty from its creation */
  52    assert(_ae_is_state_dirty(ctx));
  53
  54    exec->array.recalculate_inputs = GL_TRUE;
  55    exec->eval.recalculate_maps = GL_TRUE;
  56 }
  57
  58
  59 void vbo_exec_destroy( struct gl_context *ctx )
  60 {
  61    struct vbo_exec_context *exec = &vbo_context(ctx)->exec;
  62
  63    if (ctx->aelt_context) {
  64       _ae_destroy_context( ctx );
  65       ctx->aelt_context = NULL;
  66    }
  67
  68    vbo_exec_vtx_destroy( exec );
  69 }
  70
  71
  72 /**
  73  * Figure out the number of transform feedback primitives that will be output
  74  * considering the drawing mode, number of vertices, and instance count,
  75  * assuming that no geometry shading is done and primitive restart is not
  76  * used.
  77  *
  78  * This is used by driver back-ends in implementing the PRIMITIVES_GENERATED
  79  * and TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN queries.  It is also used to
  80  * pre-validate draw calls in GLES3 (where draw calls only succeed if there is
  81  * enough room in the transform feedback buffer for the result).
  82  */
  83 size_t
  84 vbo_count_tessellated_primitives(GLenum mode, GLuint count,
  85                                  GLuint num_instances)
  86 {
  87    size_t num_primitives;
  88    switch (mode) {
  89    case GL_POINTS:
  90       num_primitives = count;
  91       break;
  92    case GL_LINE_STRIP:
  93       num_primitives = count >= 2 ? count - 1 : 0;
  94       break;
  95    case GL_LINE_LOOP:
  96       num_primitives = count >= 2 ? count : 0;
  97       break;
  98    case GL_LINES:
  99       num_primitives = count / 2;
 100       break;
 101    case GL_TRIANGLE_STRIP:
 102    case GL_TRIANGLE_FAN:
 103    case GL_POLYGON:
 104       num_primitives = count >= 3 ? count - 2 : 0;
 105       break;
 106    case GL_TRIANGLES:
 107       num_primitives = count / 3;
 108       break;
 109    case GL_QUAD_STRIP:
 110       num_primitives = count >= 4 ? ((count / 2) - 1) * 2 : 0;
 111       break;
 112    case GL_QUADS:
 113       num_primitives = (count / 4) * 2;
 114       break;
 115    case GL_LINES_ADJACENCY:
 116       num_primitives = count / 4;
 117       break;
 118    case GL_LINE_STRIP_ADJACENCY:
 119       num_primitives = count >= 4 ? count - 3 : 0;
 120       break;
 121    case GL_TRIANGLES_ADJACENCY:
 122       num_primitives = count / 6;
 123       break;
 124    case GL_TRIANGLE_STRIP_ADJACENCY:
 125       num_primitives = count >= 6 ? (count - 4) / 2 : 0;
 126       break;
 127    default:
 128       assert(!"Unexpected primitive type in count_tessellated_primitives");
 129       num_primitives = 0;
 130       break;
 131    }
 132    return num_primitives * num_instances;
 133 }
 134
 135
 136
 137 /**
 138  * In some degenarate cases we can improve our ability to merge
 139  * consecutive primitives.  For example:
 140  * glBegin(GL_LINE_STRIP);
 141  * glVertex(1);
 142  * glVertex(1);
 143  * glEnd();
 144  * glBegin(GL_LINE_STRIP);
 145  * glVertex(1);
 146  * glVertex(1);
 147  * glEnd();
 148  * Can be merged as a GL_LINES prim with four vertices.
 149  *
 150  * This function converts 2-vertex line strips/loops into GL_LINES, etc.
 151  */
 152 void
 153 vbo_try_prim_conversion(struct _mesa_prim *p)
 154 {
 155    if (p->mode == GL_LINE_STRIP && p->count == 2) {
 156       /* convert 2-vertex line strip to a separate line */
 157       p->mode = GL_LINES;
 158    }
 159    else if ((p->mode == GL_TRIANGLE_STRIP || p->mode == GL_TRIANGLE_FAN)
 160        && p->count == 3) {
 161       /* convert 3-vertex tri strip or fan to a separate triangle */
 162       p->mode = GL_TRIANGLES;
 163    }
 164
 165    /* Note: we can't convert a 4-vertex quad strip to a separate quad
 166     * because the vertex ordering is different.  We'd have to muck
 167     * around in the vertex data to make it work.
 168     */
 169 }
 170
 171
 172 /**
 173  * Helper function for determining if two subsequent glBegin/glEnd
 174  * primitives can be combined.  This is only possible for GL_POINTS,
 175  * GL_LINES, GL_TRIANGLES and GL_QUADS.
 176  * If we return true, it means that we can concatenate p1 onto p0 (and
 177  * discard p1).
 178  */
 179 bool
 180 vbo_can_merge_prims(const struct _mesa_prim *p0, const struct _mesa_prim *p1)
 181 {
 182    if (!p0->begin ||
 183        !p1->begin ||
 184        !p0->end ||
 185        !p1->end)
 186       return false;
 187
 188    /* The prim mode must match (ex: both GL_TRIANGLES) */
 189    if (p0->mode != p1->mode)
 190       return false;
 191
 192    /* p1's vertices must come right after p0 */
 193    if (p0->start + p0->count != p1->start)
 194       return false;
 195
 196    if (p0->basevertex != p1->basevertex ||
 197        p0->num_instances != p1->num_instances ||
 198        p0->base_instance != p1->base_instance)
 199       return false;
 200
 201    /* can always merge subsequent GL_POINTS primitives */
 202    if (p0->mode == GL_POINTS)
 203       return true;
 204
 205    /* independent lines with no extra vertices */
 206    if (p0->mode == GL_LINES && p0->count % 2 == 0 && p1->count % 2 == 0)
 207       return true;
 208
 209    /* independent tris */
 210    if (p0->mode == GL_TRIANGLES && p0->count % 3 == 0 && p1->count % 3 == 0)
 211       return true;
 212
 213    /* independent quads */
 214    if (p0->mode == GL_QUADS && p0->count % 4 == 0 && p1->count % 4 == 0)
 215       return true;
 216
 217    return false;
 218 }
 219
 220
 221 /**
 222  * If we've determined that p0 and p1 can be merged, this function
 223  * concatenates p1 onto p0.
 224  */
 225 void
 226 vbo_merge_prims(struct _mesa_prim *p0, const struct _mesa_prim *p1)
 227 {
 228    assert(vbo_can_merge_prims(p0, p1));
 229
 230    p0->count += p1->count;
 231    p0->end = p1->end;
 232 }