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      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 (at) 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 }
    233