src/mesa/main/state.c

   1 /*
   2  * Mesa 3-D graphics library
   3  *
   4  * Copyright (C) 1999-2008  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
  25
  26 /**
  27  * \file state.c
  28  * State management.
  29  *
  30  * This file manages recalculation of derived values in struct gl_context.
  31  */
  32
  33
  34 #include "glheader.h"
  35 #include "mtypes.h"
  36 #include "arrayobj.h"
  37 #include "context.h"
  38 #include "debug.h"
  39 #include "macros.h"
  40 #include "ffvertex_prog.h"
  41 #include "framebuffer.h"
  42 #include "light.h"
  43 #include "matrix.h"
  44 #include "pixel.h"
  45 #include "program/program.h"
  46 #include "program/prog_parameter.h"
  47 #include "shaderobj.h"
  48 #include "state.h"
  49 #include "stencil.h"
  50 #include "texenvprogram.h"
  51 #include "texobj.h"
  52 #include "texstate.h"
  53 #include "varray.h"
  54 #include "viewport.h"
  55 #include "blend.h"
  56
  57
  58 /**
  59  * Update the following fields:
  60  *   ctx->VertexProgram._Enabled
  61  *   ctx->FragmentProgram._Enabled
  62  *   ctx->ATIFragmentShader._Enabled
  63  * This needs to be done before texture state validation.
  64  */
  65 static void
  66 update_program_enables(struct gl_context *ctx)
  67 {
  68    /* These _Enabled flags indicate if the user-defined ARB/NV vertex/fragment
  69     * program is enabled AND valid.  Similarly for ATI fragment shaders.
  70     * GLSL shaders not relevant here.
  71     */
  72    ctx->VertexProgram._Enabled = ctx->VertexProgram.Enabled
  73       && ctx->VertexProgram.Current->arb.Instructions;
  74    ctx->FragmentProgram._Enabled = ctx->FragmentProgram.Enabled
  75       && ctx->FragmentProgram.Current->arb.Instructions;
  76    ctx->ATIFragmentShader._Enabled = ctx->ATIFragmentShader.Enabled
  77       && ctx->ATIFragmentShader.Current->Instructions[0];
  78 }
  79
  80
  81 /**
  82  * Update the ctx->*Program._Current pointers to point to the
  83  * current/active programs.  Then call ctx->Driver.BindProgram() to
  84  * tell the driver which programs to use.
  85  *
  86  * Programs may come from 3 sources: GLSL shaders, ARB/NV_vertex/fragment
  87  * programs or programs derived from fixed-function state.
  88  *
  89  * This function needs to be called after texture state validation in case
  90  * we're generating a fragment program from fixed-function texture state.
  91  *
  92  * \return bitfield which will indicate _NEW_PROGRAM state if a new vertex
  93  * or fragment program is being used.
  94  */
  95 static GLbitfield
  96 update_program(struct gl_context *ctx)
  97 {
  98    const struct gl_shader_program *vsProg =
  99       ctx->_Shader->CurrentProgram[MESA_SHADER_VERTEX];
 100    const struct gl_shader_program *tcsProg =
 101       ctx->_Shader->CurrentProgram[MESA_SHADER_TESS_CTRL];
 102    const struct gl_shader_program *tesProg =
 103       ctx->_Shader->CurrentProgram[MESA_SHADER_TESS_EVAL];
 104    const struct gl_shader_program *gsProg =
 105       ctx->_Shader->CurrentProgram[MESA_SHADER_GEOMETRY];
 106    struct gl_shader_program *fsProg =
 107       ctx->_Shader->CurrentProgram[MESA_SHADER_FRAGMENT];
 108    const struct gl_shader_program *csProg =
 109       ctx->_Shader->CurrentProgram[MESA_SHADER_COMPUTE];
 110    const struct gl_program *prevVP = ctx->VertexProgram._Current;
 111    const struct gl_program *prevFP = ctx->FragmentProgram._Current;
 112    const struct gl_program *prevGP = ctx->GeometryProgram._Current;
 113    const struct gl_program *prevTCP = ctx->TessCtrlProgram._Current;
 114    const struct gl_program *prevTEP = ctx->TessEvalProgram._Current;
 115    const struct gl_program *prevCP = ctx->ComputeProgram._Current;
 116    GLbitfield new_state = 0x0;
 117
 118    /*
 119     * Set the ctx->VertexProgram._Current and ctx->FragmentProgram._Current
 120     * pointers to the programs that should be used for rendering.  If either
 121     * is NULL, use fixed-function code paths.
 122     *
 123     * These programs may come from several sources.  The priority is as
 124     * follows:
 125     *   1. OpenGL 2.0/ARB vertex/fragment shaders
 126     *   2. ARB/NV vertex/fragment programs
 127     *   3. ATI fragment shader
 128     *   4. Programs derived from fixed-function state.
 129     *
 130     * Note: it's possible for a vertex shader to get used with a fragment
 131     * program (and vice versa) here, but in practice that shouldn't ever
 132     * come up, or matter.
 133     */
 134
 135    if (fsProg && fsProg->data->LinkStatus
 136        && fsProg->_LinkedShaders[MESA_SHADER_FRAGMENT]) {
 137       /* Use GLSL fragment shader */
 138       _mesa_reference_program(ctx, &ctx->_Shader->_CurrentFragmentProgram,
 139                               fsProg->_LinkedShaders[MESA_SHADER_FRAGMENT]->Program);
 140       _mesa_reference_program(ctx, &ctx->FragmentProgram._Current,
 141                               fsProg->_LinkedShaders[MESA_SHADER_FRAGMENT]->Program);
 142       _mesa_reference_program(ctx, &ctx->FragmentProgram._TexEnvProgram,
 143                               NULL);
 144    }
 145    else if (ctx->FragmentProgram._Enabled) {
 146       /* Use user-defined fragment program */
 147       _mesa_reference_program(ctx, &ctx->_Shader->_CurrentFragmentProgram,
 148                               NULL);
 149       _mesa_reference_program(ctx, &ctx->FragmentProgram._Current,
 150                               ctx->FragmentProgram.Current);
 151       _mesa_reference_program(ctx, &ctx->FragmentProgram._TexEnvProgram,
 152                               NULL);
 153    }
 154    else if (ctx->ATIFragmentShader._Enabled &&
 155             ctx->ATIFragmentShader.Current->Program) {
 156        /* Use the enabled ATI fragment shader's associated program */
 157       _mesa_reference_program(ctx, &ctx->_Shader->_CurrentFragmentProgram,
 158                               NULL);
 159       _mesa_reference_program(ctx, &ctx->FragmentProgram._Current,
 160                               ctx->ATIFragmentShader.Current->Program);
 161       _mesa_reference_program(ctx, &ctx->FragmentProgram._TexEnvProgram,
 162                               NULL);
 163    }
 164    else if (ctx->FragmentProgram._MaintainTexEnvProgram) {
 165       /* Use fragment program generated from fixed-function state */
 166       struct gl_shader_program *f = _mesa_get_fixed_func_fragment_program(ctx);
 167
 168       _mesa_reference_program(ctx, &ctx->_Shader->_CurrentFragmentProgram,
 169                               f->_LinkedShaders[MESA_SHADER_FRAGMENT]->Program);
 170       _mesa_reference_program(ctx, &ctx->FragmentProgram._Current,
 171                               f->_LinkedShaders[MESA_SHADER_FRAGMENT]->Program);
 172       _mesa_reference_program(ctx, &ctx->FragmentProgram._TexEnvProgram,
 173                               f->_LinkedShaders[MESA_SHADER_FRAGMENT]->Program);
 174    }
 175    else {
 176       /* No fragment program */
 177       _mesa_reference_program(ctx, &ctx->FragmentProgram._Current, NULL);
 178       _mesa_reference_program(ctx, &ctx->FragmentProgram._TexEnvProgram,
 179                               NULL);
 180    }
 181
 182    if (gsProg && gsProg->data->LinkStatus
 183        && gsProg->_LinkedShaders[MESA_SHADER_GEOMETRY]) {
 184       /* Use GLSL geometry shader */
 185       _mesa_reference_program(ctx, &ctx->GeometryProgram._Current,
 186                               gsProg->_LinkedShaders[MESA_SHADER_GEOMETRY]->Program);
 187    } else {
 188       /* No geometry program */
 189       _mesa_reference_program(ctx, &ctx->GeometryProgram._Current, NULL);
 190    }
 191
 192    if (tesProg && tesProg->data->LinkStatus
 193        && tesProg->_LinkedShaders[MESA_SHADER_TESS_EVAL]) {
 194       /* Use GLSL tessellation evaluation shader */
 195       _mesa_reference_program(ctx, &ctx->TessEvalProgram._Current,
 196          tesProg->_LinkedShaders[MESA_SHADER_TESS_EVAL]->Program);
 197    }
 198    else {
 199       /* No tessellation evaluation program */
 200       _mesa_reference_program(ctx, &ctx->TessEvalProgram._Current, NULL);
 201    }
 202
 203    if (tcsProg && tcsProg->data->LinkStatus
 204        && tcsProg->_LinkedShaders[MESA_SHADER_TESS_CTRL]) {
 205       /* Use GLSL tessellation control shader */
 206       _mesa_reference_program(ctx, &ctx->TessCtrlProgram._Current,
 207           tcsProg->_LinkedShaders[MESA_SHADER_TESS_CTRL]->Program);
 208    }
 209    else {
 210       /* No tessellation control program */
 211       _mesa_reference_program(ctx, &ctx->TessCtrlProgram._Current, NULL);
 212    }
 213
 214    /* Examine vertex program after fragment program as
 215     * _mesa_get_fixed_func_vertex_program() needs to know active
 216     * fragprog inputs.
 217     */
 218    if (vsProg && vsProg->data->LinkStatus
 219        && vsProg->_LinkedShaders[MESA_SHADER_VERTEX]) {
 220       /* Use GLSL vertex shader */
 221       _mesa_reference_program(ctx, &ctx->VertexProgram._Current,
 222                               vsProg->_LinkedShaders[MESA_SHADER_VERTEX]->Program);
 223    }
 224    else if (ctx->VertexProgram._Enabled) {
 225       /* Use user-defined vertex program */
 226       _mesa_reference_program(ctx, &ctx->VertexProgram._Current,
 227                               ctx->VertexProgram.Current);
 228    }
 229    else if (ctx->VertexProgram._MaintainTnlProgram) {
 230       /* Use vertex program generated from fixed-function state */
 231       _mesa_reference_program(ctx, &ctx->VertexProgram._Current,
 232                               _mesa_get_fixed_func_vertex_program(ctx));
 233       _mesa_reference_program(ctx, &ctx->VertexProgram._TnlProgram,
 234                               ctx->VertexProgram._Current);
 235    }
 236    else {
 237       /* no vertex program */
 238       _mesa_reference_program(ctx, &ctx->VertexProgram._Current, NULL);
 239    }
 240
 241    if (csProg && csProg->data->LinkStatus
 242        && csProg->_LinkedShaders[MESA_SHADER_COMPUTE]) {
 243       /* Use GLSL compute shader */
 244       _mesa_reference_program(ctx, &ctx->ComputeProgram._Current,
 245                               csProg->_LinkedShaders[MESA_SHADER_COMPUTE]->Program);
 246    } else {
 247       /* no compute program */
 248       _mesa_reference_program(ctx, &ctx->ComputeProgram._Current, NULL);
 249    }
 250
 251    /* Let the driver know what's happening:
 252     */
 253    if (ctx->FragmentProgram._Current != prevFP) {
 254       new_state |= _NEW_PROGRAM;
 255       if (ctx->Driver.BindProgram) {
 256          ctx->Driver.BindProgram(ctx, GL_FRAGMENT_PROGRAM_ARB,
 257                                  ctx->FragmentProgram._Current);
 258       }
 259    }
 260
 261    if (ctx->GeometryProgram._Current != prevGP) {
 262       new_state |= _NEW_PROGRAM;
 263       if (ctx->Driver.BindProgram) {
 264          ctx->Driver.BindProgram(ctx, GL_GEOMETRY_PROGRAM_NV,
 265                                  ctx->GeometryProgram._Current);
 266       }
 267    }
 268
 269    if (ctx->TessEvalProgram._Current != prevTEP) {
 270       new_state |= _NEW_PROGRAM;
 271       if (ctx->Driver.BindProgram) {
 272          ctx->Driver.BindProgram(ctx, GL_TESS_EVALUATION_PROGRAM_NV,
 273                                  ctx->TessEvalProgram._Current);
 274       }
 275    }
 276
 277    if (ctx->TessCtrlProgram._Current != prevTCP) {
 278       new_state |= _NEW_PROGRAM;
 279       if (ctx->Driver.BindProgram) {
 280          ctx->Driver.BindProgram(ctx, GL_TESS_CONTROL_PROGRAM_NV,
 281                                  ctx->TessCtrlProgram._Current);
 282       }
 283    }
 284
 285    if (ctx->VertexProgram._Current != prevVP) {
 286       new_state |= _NEW_PROGRAM;
 287       if (ctx->Driver.BindProgram) {
 288          ctx->Driver.BindProgram(ctx, GL_VERTEX_PROGRAM_ARB,
 289                                  ctx->VertexProgram._Current);
 290       }
 291    }
 292
 293    if (ctx->ComputeProgram._Current != prevCP) {
 294       new_state |= _NEW_PROGRAM;
 295       if (ctx->Driver.BindProgram) {
 296          ctx->Driver.BindProgram(ctx, GL_COMPUTE_PROGRAM_NV,
 297                                  ctx->ComputeProgram._Current);
 298       }
 299    }
 300
 301    return new_state;
 302 }
 303
 304
 305 /**
 306  * Examine shader constants and return either _NEW_PROGRAM_CONSTANTS or 0.
 307  */
 308 static GLbitfield
 309 update_program_constants(struct gl_context *ctx)
 310 {
 311    GLbitfield new_state = 0x0;
 312
 313    if (ctx->FragmentProgram._Current) {
 314       const struct gl_program_parameter_list *params =
 315          ctx->FragmentProgram._Current->Parameters;
 316       if (params && params->StateFlags & ctx->NewState) {
 317          new_state |= _NEW_PROGRAM_CONSTANTS;
 318       }
 319    }
 320
 321    /* Don't handle tessellation and geometry shaders here. They don't use
 322     * any state constants.
 323     */
 324
 325    if (ctx->VertexProgram._Current) {
 326       const struct gl_program_parameter_list *params =
 327          ctx->VertexProgram._Current->Parameters;
 328       if (params && params->StateFlags & ctx->NewState) {
 329          new_state |= _NEW_PROGRAM_CONSTANTS;
 330       }
 331    }
 332
 333    return new_state;
 334 }
 335
 336
 337
 338
 339 /**
 340  * Update the ctx->Polygon._FrontBit flag.
 341  */
 342 static void
 343 update_frontbit(struct gl_context *ctx)
 344 {
 345    if (ctx->Transform.ClipOrigin == GL_LOWER_LEFT)
 346       ctx->Polygon._FrontBit = (ctx->Polygon.FrontFace == GL_CW);
 347    else
 348       ctx->Polygon._FrontBit = (ctx->Polygon.FrontFace == GL_CCW);
 349 }
 350
 351
 352 /**
 353  * Update the ctx->VertexProgram._TwoSideEnabled flag.
 354  */
 355 static void
 356 update_twoside(struct gl_context *ctx)
 357 {
 358    if (ctx->_Shader->CurrentProgram[MESA_SHADER_VERTEX] ||
 359        ctx->VertexProgram._Enabled) {
 360       ctx->VertexProgram._TwoSideEnabled = ctx->VertexProgram.TwoSideEnabled;
 361    } else {
 362       ctx->VertexProgram._TwoSideEnabled = (ctx->Light.Enabled &&
 363                                             ctx->Light.Model.TwoSide);
 364    }
 365 }
 366
 367
 368 /**
 369  * Compute derived GL state.
 370  * If __struct gl_contextRec::NewState is non-zero then this function \b must
 371  * be called before rendering anything.
 372  *
 373  * Calls dd_function_table::UpdateState to perform any internal state
 374  * management necessary.
 375  *
 376  * \sa _mesa_update_modelview_project(), _mesa_update_texture(),
 377  * _mesa_update_buffer_bounds(),
 378  * _mesa_update_lighting() and _mesa_update_tnl_spaces().
 379  */
 380 void
 381 _mesa_update_state_locked( struct gl_context *ctx )
 382 {
 383    GLbitfield new_state = ctx->NewState;
 384    GLbitfield prog_flags = _NEW_PROGRAM;
 385    GLbitfield new_prog_state = 0x0;
 386    const GLbitfield computed_states = ~(_NEW_CURRENT_ATTRIB | _NEW_LINE);
 387
 388    /* we can skip a bunch of state validation checks if the dirty
 389     * state matches one or more bits in 'computed_states'.
 390     */
 391    if ((new_state & computed_states) == 0)
 392       goto out;
 393
 394    if (MESA_VERBOSE & VERBOSE_STATE)
 395       _mesa_print_state("_mesa_update_state", new_state);
 396
 397    /* Determine which state flags effect vertex/fragment program state */
 398    if (ctx->FragmentProgram._MaintainTexEnvProgram) {
 399       prog_flags |= (_NEW_BUFFERS | _NEW_TEXTURE | _NEW_FOG |
 400                      _NEW_VARYING_VP_INPUTS | _NEW_LIGHT | _NEW_POINT |
 401                      _NEW_RENDERMODE | _NEW_PROGRAM | _NEW_FRAG_CLAMP |
 402                      _NEW_COLOR);
 403    }
 404    if (ctx->VertexProgram._MaintainTnlProgram) {
 405       prog_flags |= (_NEW_VARYING_VP_INPUTS | _NEW_TEXTURE |
 406                      _NEW_TEXTURE_MATRIX | _NEW_TRANSFORM | _NEW_POINT |
 407                      _NEW_FOG | _NEW_LIGHT |
 408                      _MESA_NEW_NEED_EYE_COORDS);
 409    }
 410
 411    /*
 412     * Now update derived state info
 413     */
 414
 415    if (new_state & prog_flags)
 416       update_program_enables( ctx );
 417
 418    if (new_state & (_NEW_MODELVIEW|_NEW_PROJECTION))
 419       _mesa_update_modelview_project( ctx, new_state );
 420
 421    if (new_state & (_NEW_PROGRAM|_NEW_TEXTURE|_NEW_TEXTURE_MATRIX))
 422       _mesa_update_texture( ctx, new_state );
 423
 424    if (new_state & _NEW_POLYGON)
 425       update_frontbit( ctx );
 426
 427    if (new_state & _NEW_BUFFERS)
 428       _mesa_update_framebuffer(ctx, ctx->ReadBuffer, ctx->DrawBuffer);
 429
 430    if (new_state & (_NEW_SCISSOR | _NEW_BUFFERS | _NEW_VIEWPORT))
 431       _mesa_update_draw_buffer_bounds(ctx, ctx->DrawBuffer);
 432
 433    if (new_state & _NEW_LIGHT)
 434       _mesa_update_lighting( ctx );
 435
 436    if (new_state & (_NEW_LIGHT | _NEW_PROGRAM))
 437       update_twoside( ctx );
 438
 439    if (new_state & (_NEW_STENCIL | _NEW_BUFFERS))
 440       _mesa_update_stencil( ctx );
 441
 442    if (new_state & _NEW_PIXEL)
 443       _mesa_update_pixel( ctx, new_state );
 444
 445    /* ctx->_NeedEyeCoords is now up to date.
 446     *
 447     * If the truth value of this variable has changed, update for the
 448     * new lighting space and recompute the positions of lights and the
 449     * normal transform.
 450     *
 451     * If the lighting space hasn't changed, may still need to recompute
 452     * light positions & normal transforms for other reasons.
 453     */
 454    if (new_state & _MESA_NEW_NEED_EYE_COORDS)
 455       _mesa_update_tnl_spaces( ctx, new_state );
 456
 457    if (new_state & prog_flags) {
 458       /* When we generate programs from fixed-function vertex/fragment state
 459        * this call may generate/bind a new program.  If so, we need to
 460        * propogate the _NEW_PROGRAM flag to the driver.
 461        */
 462       new_prog_state |= update_program( ctx );
 463    }
 464
 465    if (new_state & _NEW_ARRAY)
 466       _mesa_update_vao_client_arrays(ctx, ctx->Array.VAO);
 467
 468  out:
 469    new_prog_state |= update_program_constants(ctx);
 470
 471    /*
 472     * Give the driver a chance to act upon the new_state flags.
 473     * The driver might plug in different span functions, for example.
 474     * Also, this is where the driver can invalidate the state of any
 475     * active modules (such as swrast_setup, swrast, tnl, etc).
 476     *
 477     * Set ctx->NewState to zero to avoid recursion if
 478     * Driver.UpdateState() has to call FLUSH_VERTICES().  (fixed?)
 479     */
 480    new_state = ctx->NewState | new_prog_state;
 481    ctx->NewState = 0;
 482    ctx->Driver.UpdateState(ctx, new_state);
 483    ctx->Array.VAO->NewArrays = 0x0;
 484 }
 485
 486
 487 /* This is the usual entrypoint for state updates:
 488  */
 489 void
 490 _mesa_update_state( struct gl_context *ctx )
 491 {
 492    _mesa_lock_context_textures(ctx);
 493    _mesa_update_state_locked(ctx);
 494    _mesa_unlock_context_textures(ctx);
 495 }
 496
 497
 498
 499
 500 /**
 501  * Want to figure out which fragment program inputs are actually
 502  * constant/current values from ctx->Current.  These should be
 503  * referenced as a tracked state variable rather than a fragment
 504  * program input, to save the overhead of putting a constant value in
 505  * every submitted vertex, transferring it to hardware, interpolating
 506  * it across the triangle, etc...
 507  *
 508  * When there is a VP bound, just use vp->outputs.  But when we're
 509  * generating vp from fixed function state, basically want to
 510  * calculate:
 511  *
 512  * vp_out_2_fp_in( vp_in_2_vp_out( varying_inputs ) |
 513  *                 potential_vp_outputs )
 514  *
 515  * Where potential_vp_outputs is calculated by looking at enabled
 516  * texgen, etc.
 517  *
 518  * The generated fragment program should then only declare inputs that
 519  * may vary or otherwise differ from the ctx->Current values.
 520  * Otherwise, the fp should track them as state values instead.
 521  */
 522 void
 523 _mesa_set_varying_vp_inputs( struct gl_context *ctx,
 524                              GLbitfield64 varying_inputs )
 525 {
 526    if (ctx->varying_vp_inputs != varying_inputs) {
 527       ctx->varying_vp_inputs = varying_inputs;
 528
 529       /* Only the fixed-func generated programs need to use the flag
 530        * and the fixed-func fragment program uses it only if there is also
 531        * a fixed-func vertex program, so this only depends on the latter.
 532        *
 533        * It's okay to check the VP pointer here, because this is called after
 534        * _mesa_update_state in the vbo module. */
 535       if (ctx->VertexProgram._TnlProgram ||
 536           ctx->FragmentProgram._TexEnvProgram) {
 537          ctx->NewState |= _NEW_VARYING_VP_INPUTS;
 538       }
 539       /*printf("%s %x\n", __func__, varying_inputs);*/
 540    }
 541 }
 542
 543
 544 /**
 545  * Used by drivers to tell core Mesa that the driver is going to
 546  * install/ use its own vertex program.  In particular, this will
 547  * prevent generated fragment programs from using state vars instead
 548  * of ordinary varyings/inputs.
 549  */
 550 void
 551 _mesa_set_vp_override(struct gl_context *ctx, GLboolean flag)
 552 {
 553    if (ctx->VertexProgram._Overriden != flag) {
 554       ctx->VertexProgram._Overriden = flag;
 555
 556       /* Set one of the bits which will trigger fragment program
 557        * regeneration:
 558        */
 559       ctx->NewState |= _NEW_PROGRAM;
 560    }
 561 }