src/mesa/state_tracker/st_cb_clear.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
   4  * 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
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  21  * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
  22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27
  28  /*
  29   * Authors:
  30   *   Keith Whitwell <keith@tungstengraphics.com>
  31   *   Brian Paul
  32   */
  33
  34 #include "main/glheader.h"
  35 #include "main/macros.h"
  36 #include "shader/prog_instruction.h"
  37 #include "st_atom.h"
  38 #include "st_cache.h"
  39 #include "st_context.h"
  40 #include "st_cb_clear.h"
  41 #include "st_cb_fbo.h"
  42 #include "st_draw.h"
  43 #include "st_program.h"
  44 #include "st_public.h"
  45
  46 #include "pipe/p_context.h"
  47 #include "pipe/p_state.h"
  48 #include "pipe/p_defines.h"
  49 #include "pipe/p_winsys.h"
  50
  51 #include "pipe/tgsi/mesa/mesa_to_tgsi.h"
  52
  53 #include "vf/vf.h"
  54
  55
  56
  57
  58 static GLuint
  59 color_value(GLuint pipeFormat, const GLfloat color[4])
  60 {
  61    GLubyte r, g, b, a;
  62
  63    UNCLAMPED_FLOAT_TO_UBYTE(r, color[0]);
  64    UNCLAMPED_FLOAT_TO_UBYTE(g, color[1]);
  65    UNCLAMPED_FLOAT_TO_UBYTE(b, color[2]);
  66    UNCLAMPED_FLOAT_TO_UBYTE(a, color[3]);
  67
  68    switch (pipeFormat) {
  69    case PIPE_FORMAT_U_R8_G8_B8_A8:
  70       return (r << 24) | (g << 16) | (b << 8) | a;
  71    case PIPE_FORMAT_U_A8_R8_G8_B8:
  72       return (a << 24) | (r << 16) | (g << 8) | b;
  73    case PIPE_FORMAT_U_R5_G6_B5:
  74       return ((r & 0xf8) << 8) | ((g & 0xfc) << 3) | (b >> 3);
  75    default:
  76       return 0;
  77    }
  78 }
  79
  80
  81 static GLuint
  82 depth_value(GLuint pipeFormat, GLfloat value)
  83 {
  84    GLuint val;
  85    switch (pipeFormat) {
  86    case PIPE_FORMAT_U_Z16:
  87       val = (GLuint) (value * 0xffffff);
  88       break;
  89    case PIPE_FORMAT_U_Z32:
  90       val = (GLuint) (value * 0xffffffff);
  91       break;
  92    case PIPE_FORMAT_S8_Z24:
  93    /*case PIPE_FORMAT_Z24_S8:*/
  94       val = (GLuint) (value * 0xffffff);
  95       break;
  96    default:
  97       val = 0;
  98       assert(0);
  99    }
 100    return val;
 101 }
 102
 103
 104 static GLboolean
 105 is_depth_stencil_format(GLuint pipeFormat)
 106 {
 107    switch (pipeFormat) {
 108    case PIPE_FORMAT_S8_Z24:
 109    /*case PIPE_FORMAT_Z24_S8:*/
 110       return GL_TRUE;
 111    default:
 112       return GL_FALSE;
 113    }
 114 }
 115
 116
 117
 118 /**
 119  * Create a simple fragment shader that just passes through the fragment color.
 120  */
 121 static struct st_fragment_program *
 122 make_frag_shader(struct st_context *st)
 123 {
 124    GLcontext *ctx = st->ctx;
 125    struct st_fragment_program *stfp;
 126    struct gl_program *p;
 127    GLuint interpMode[16];
 128    GLuint i;
 129
 130    /* XXX temporary */
 131    for (i = 0; i < 16; i++)
 132       interpMode[i] = TGSI_INTERPOLATE_LINEAR;
 133
 134    p = ctx->Driver.NewProgram(ctx, GL_FRAGMENT_PROGRAM_ARB, 0);
 135    if (!p)
 136       return NULL;
 137
 138    p->NumInstructions = 2;
 139    p->Instructions = _mesa_alloc_instructions(2);
 140    if (!p->Instructions) {
 141       ctx->Driver.DeleteProgram(ctx, p);
 142       return NULL;
 143    }
 144    _mesa_init_instructions(p->Instructions, 2);
 145    /* MOV result.color, fragment.color; */
 146    p->Instructions[0].Opcode = OPCODE_MOV;
 147    p->Instructions[0].DstReg.File = PROGRAM_OUTPUT;
 148    p->Instructions[0].DstReg.Index = FRAG_RESULT_COLR;
 149    p->Instructions[0].SrcReg[0].File = PROGRAM_INPUT;
 150    p->Instructions[0].SrcReg[0].Index = FRAG_ATTRIB_COL0;
 151    /* END; */
 152    p->Instructions[1].Opcode = OPCODE_END;
 153
 154    p->InputsRead = FRAG_BIT_COL0;
 155    p->OutputsWritten = (1 << FRAG_RESULT_COLR);
 156
 157    stfp = (struct st_fragment_program *) p;
 158    st_translate_fragment_shader(st, stfp);
 159
 160    return stfp;
 161 }
 162
 163
 164 /**
 165  * Create a simple vertex shader that just passes through the
 166  * vertex position and color.
 167  */
 168 static struct st_vertex_program *
 169 make_vertex_shader(struct st_context *st)
 170 {
 171    GLcontext *ctx = st->ctx;
 172    struct st_vertex_program *stvp;
 173    struct gl_program *p;
 174
 175    p = ctx->Driver.NewProgram(ctx, GL_VERTEX_PROGRAM_ARB, 0);
 176    if (!p)
 177       return NULL;
 178
 179    p->NumInstructions = 3;
 180    p->Instructions = _mesa_alloc_instructions(3);
 181    if (!p->Instructions) {
 182       ctx->Driver.DeleteProgram(ctx, p);
 183       return NULL;
 184    }
 185    _mesa_init_instructions(p->Instructions, 3);
 186    /* MOV result.pos, vertex.pos; */
 187    p->Instructions[0].Opcode = OPCODE_MOV;
 188    p->Instructions[0].DstReg.File = PROGRAM_OUTPUT;
 189    p->Instructions[0].DstReg.Index = VERT_RESULT_HPOS;
 190    p->Instructions[0].SrcReg[0].File = PROGRAM_INPUT;
 191    p->Instructions[0].SrcReg[0].Index = VERT_ATTRIB_POS;
 192    /* MOV result.color, vertex.color; */
 193    p->Instructions[1].Opcode = OPCODE_MOV;
 194    p->Instructions[1].DstReg.File = PROGRAM_OUTPUT;
 195    p->Instructions[1].DstReg.Index = VERT_RESULT_COL0;
 196    p->Instructions[1].SrcReg[0].File = PROGRAM_INPUT;
 197    p->Instructions[1].SrcReg[0].Index = VERT_ATTRIB_COLOR0;
 198    /* END; */
 199    p->Instructions[2].Opcode = OPCODE_END;
 200
 201    p->InputsRead = VERT_BIT_POS | VERT_BIT_COLOR0;
 202    p->OutputsWritten = ((1 << VERT_RESULT_COL0) |
 203                         (1 << VERT_RESULT_HPOS));
 204
 205    stvp = (struct st_vertex_program *) p;
 206    st_translate_vertex_shader(st, stvp);
 207    assert(stvp->vs);
 208
 209    return stvp;
 210 }
 211
 212
 213
 214 /**
 215  * Draw a screen-aligned quadrilateral.
 216  * Coords are window coords with y=0=bottom.  These coords will be transformed
 217  * by the vertex shader and viewport transform (which will flip Y if needed).
 218  */
 219 static void
 220 draw_quad(GLcontext *ctx,
 221           float x0, float y0, float x1, float y1, GLfloat z,
 222           const GLfloat color[4])
 223 {
 224    static const GLuint attribs[2] = {
 225       0, /* pos */
 226       3  /* color */
 227    };
 228    GLfloat verts[4][2][4]; /* four verts, two attribs, XYZW */
 229    GLuint i;
 230
 231    /* positions */
 232    verts[0][0][0] = x0;
 233    verts[0][0][1] = y0;
 234
 235    verts[1][0][0] = x1;
 236    verts[1][0][1] = y0;
 237
 238    verts[2][0][0] = x1;
 239    verts[2][0][1] = y1;
 240
 241    verts[3][0][0] = x0;
 242    verts[3][0][1] = y1;
 243
 244    /* same for all verts: */
 245    for (i = 0; i < 4; i++) {
 246       verts[i][0][2] = z;
 247       verts[i][0][3] = 1.0;
 248       verts[i][1][0] = color[0];
 249       verts[i][1][1] = color[1];
 250       verts[i][1][2] = color[2];
 251       verts[i][1][3] = color[3];
 252    }
 253
 254    st_draw_vertices(ctx, PIPE_PRIM_QUADS, 4, (float *) verts, 2, attribs);
 255 }
 256
 257
 258
 259 /**
 260  * Do glClear by drawing a quadrilateral.
 261  * The vertices of the quad will be computed from the
 262  * ctx->DrawBuffer->_X/Ymin/max fields.
 263  */
 264 static void
 265 clear_with_quad(GLcontext *ctx,
 266                 GLboolean color, GLboolean depth, GLboolean stencil)
 267 {
 268    struct st_context *st = ctx->st;
 269    struct pipe_context *pipe = ctx->st->pipe;
 270    const GLfloat x0 = ctx->DrawBuffer->_Xmin;
 271    const GLfloat y0 = ctx->DrawBuffer->_Ymin;
 272    const GLfloat x1 = ctx->DrawBuffer->_Xmax;
 273    const GLfloat y1 = ctx->DrawBuffer->_Ymax;
 274
 275    /* alpha state: disabled */
 276    {
 277       struct pipe_alpha_test_state alpha_test;
 278       memset(&alpha_test, 0, sizeof(alpha_test));
 279       pipe->set_alpha_test_state(pipe, &alpha_test);
 280    }
 281
 282    /* blend state: RGBA masking */
 283    {
 284       struct pipe_blend_state blend;
 285       const struct cso_blend *cso;
 286       memset(&blend, 0, sizeof(blend));
 287       if (color) {
 288          if (ctx->Color.ColorMask[0])
 289             blend.colormask |= PIPE_MASK_R;
 290          if (ctx->Color.ColorMask[1])
 291             blend.colormask |= PIPE_MASK_G;
 292          if (ctx->Color.ColorMask[2])
 293             blend.colormask |= PIPE_MASK_B;
 294          if (ctx->Color.ColorMask[3])
 295             blend.colormask |= PIPE_MASK_A;
 296          if (st->ctx->Color.DitherFlag)
 297             blend.dither = 1;
 298       }
 299       cso = st_cached_blend_state(st, &blend);
 300       pipe->bind_blend_state(pipe, cso->data);
 301    }
 302
 303    /* depth_stencil state: always pass/set to ref value */
 304    {
 305       struct pipe_depth_stencil_state depth_stencil;
 306       const struct cso_depth_stencil *cso;
 307       memset(&depth_stencil, 0, sizeof(depth_stencil));
 308       if (depth) {
 309          depth_stencil.depth.enabled = 1;
 310          depth_stencil.depth.writemask = 1;
 311          depth_stencil.depth.func = PIPE_FUNC_ALWAYS;
 312       }
 313
 314       if (stencil) {
 315          depth_stencil.stencil.front_enabled = 1;
 316          depth_stencil.stencil.front_func = PIPE_FUNC_ALWAYS;
 317          depth_stencil.stencil.front_fail_op = PIPE_STENCIL_OP_REPLACE;
 318          depth_stencil.stencil.front_zpass_op = PIPE_STENCIL_OP_REPLACE;
 319          depth_stencil.stencil.front_zfail_op = PIPE_STENCIL_OP_REPLACE;
 320          depth_stencil.stencil.ref_value[0] = ctx->Stencil.Clear;
 321          depth_stencil.stencil.value_mask[0] = 0xff;
 322          depth_stencil.stencil.write_mask[0] = ctx->Stencil.WriteMask[0] & 0xff;
 323       }
 324       cso = st_cached_depth_stencil_state(ctx->st, &depth_stencil);
 325       pipe->bind_depth_stencil_state(pipe, cso->data);
 326    }
 327
 328    /* setup state: nothing */
 329    {
 330       struct pipe_rasterizer_state raster;
 331       const struct cso_rasterizer *cso;
 332       memset(&raster, 0, sizeof(raster));
 333 #if 0
 334       /* don't do per-pixel scissor; we'll just draw a PIPE_PRIM_QUAD
 335        * that matches the scissor bounds.
 336        */
 337       if (ctx->Scissor.Enabled)
 338          raster.scissor = 1;
 339 #endif
 340       cso = st_cached_rasterizer_state(ctx->st, &raster);
 341       pipe->bind_rasterizer_state(pipe, cso->data);
 342    }
 343
 344    /* fragment shader state: color pass-through program */
 345    {
 346       static struct st_fragment_program *stfp = NULL;
 347       if (!stfp) {
 348          stfp = make_frag_shader(st);
 349       }
 350       pipe->bind_fs_state(pipe, stfp->fs->data);
 351    }
 352
 353    /* vertex shader state: color/position pass-through */
 354    {
 355       static struct st_vertex_program *stvp = NULL;
 356       if (!stvp) {
 357          stvp = make_vertex_shader(st);
 358       }
 359       pipe->bind_vs_state(pipe, stvp->vs->data);
 360    }
 361
 362    /* viewport state: viewport matching window dims */
 363    {
 364       const float width = ctx->DrawBuffer->Width;
 365       const float height = ctx->DrawBuffer->Height;
 366       struct pipe_viewport_state vp;
 367       vp.scale[0] =  0.5 * width;
 368       vp.scale[1] = -0.5 * height;
 369       vp.scale[2] = 0.5;
 370       vp.scale[3] = 1.0;
 371       vp.translate[0] = 0.5 * width;
 372       vp.translate[1] = 0.5 * height;
 373       vp.translate[2] = 0.5;
 374       vp.translate[3] = 0.0;
 375       pipe->set_viewport_state(pipe, &vp);
 376    }
 377
 378    /* draw quad matching scissor rect (XXX verify coord round-off) */
 379    draw_quad(ctx, x0, y0, x1, y1, ctx->Depth.Clear, ctx->Color.ClearColor);
 380
 381    /* Restore pipe state */
 382    pipe->set_alpha_test_state(pipe, &st->state.alpha_test);
 383    pipe->bind_blend_state(pipe, st->state.blend->data);
 384    pipe->bind_depth_stencil_state(pipe, st->state.depth_stencil->data);
 385    pipe->bind_fs_state(pipe, st->state.fs->data);
 386    pipe->bind_vs_state(pipe, st->state.vs->data);
 387    pipe->bind_rasterizer_state(pipe, st->state.rasterizer->data);
 388    pipe->set_viewport_state(pipe, &ctx->st->state.viewport);
 389    /* OR:
 390    st_invalidate_state(ctx, _NEW_COLOR | _NEW_DEPTH | _NEW_STENCIL);
 391    */
 392 }
 393
 394
 395 /**
 396  * Determine if we need to clear the depth buffer by drawing a quad.
 397  */
 398 static INLINE GLboolean
 399 check_clear_color_with_quad(GLcontext *ctx)
 400 {
 401    return !(ctx->Color.ColorMask[0] &&
 402             ctx->Color.ColorMask[1] &&
 403             ctx->Color.ColorMask[2] &&
 404             ctx->Color.ColorMask[3] &&
 405             !ctx->Scissor.Enabled);
 406 }
 407
 408
 409 /**
 410  * Determine if we need to clear the depth buffer by drawing a quad.
 411  */
 412 static INLINE GLboolean
 413 check_clear_depth_with_quad(GLcontext *ctx, struct gl_renderbuffer *rb)
 414 {
 415    const struct st_renderbuffer *strb = st_renderbuffer(rb);
 416    const GLboolean isDS = is_depth_stencil_format(strb->surface->format);
 417    return  ctx->Scissor.Enabled
 418       || (isDS && ctx->DrawBuffer->Visual.stencilBits > 0);
 419 }
 420
 421
 422 /**
 423  * Determine if we need to clear the stencil buffer by drawing a quad.
 424  */
 425 static INLINE GLboolean
 426 check_clear_stencil_with_quad(GLcontext *ctx, struct gl_renderbuffer *rb)
 427 {
 428    const struct st_renderbuffer *strb = st_renderbuffer(rb);
 429    const GLboolean isDS = is_depth_stencil_format(strb->surface->format);
 430    const GLuint stencilMax = (1 << rb->StencilBits) - 1;
 431    const GLboolean maskStencil
 432       = (ctx->Stencil.WriteMask[0] & stencilMax) != stencilMax;
 433    return maskStencil
 434       || ctx->Scissor.Enabled
 435       || (isDS && ctx->DrawBuffer->Visual.depthBits > 0);
 436 }
 437
 438
 439
 440
 441 static void
 442 clear_color_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 443 {
 444    struct st_renderbuffer *strb = st_renderbuffer(rb);
 445
 446    if (ctx->Color.ColorMask[0] &&
 447        ctx->Color.ColorMask[1] &&
 448        ctx->Color.ColorMask[2] &&
 449        ctx->Color.ColorMask[3] &&
 450        !ctx->Scissor.Enabled)
 451    {
 452       /* clear whole buffer w/out masking */
 453       GLuint clearValue
 454          = color_value(strb->surface->format, ctx->Color.ClearColor);
 455       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 456    }
 457    else {
 458       /* masking or scissoring */
 459       clear_with_quad(ctx, GL_TRUE, GL_FALSE, GL_FALSE);
 460    }
 461 }
 462
 463
 464 static void
 465 clear_accum_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 466 {
 467    struct st_renderbuffer *strb = st_renderbuffer(rb);
 468
 469    if (!ctx->Scissor.Enabled) {
 470       /* clear whole buffer w/out masking */
 471       GLuint clearValue
 472          = color_value(strb->surface->format, ctx->Accum.ClearColor);
 473       /* Note that clearValue is 32 bits but the accum buffer will
 474        * typically be 64bpp...
 475        */
 476       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 477    }
 478    else {
 479       /* scissoring */
 480       /* XXX point framebuffer.cbufs[0] at the accum buffer */
 481       clear_with_quad(ctx, GL_TRUE, GL_FALSE, GL_FALSE);
 482    }
 483 }
 484
 485
 486 static void
 487 clear_depth_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 488 {
 489    struct st_renderbuffer *strb = st_renderbuffer(rb);
 490    const GLboolean isDS = is_depth_stencil_format(strb->surface->format);
 491
 492    assert(strb->surface->format);
 493
 494 #if 0
 495    if (ctx->Scissor.Enabled ||
 496        (isDS && ctx->DrawBuffer->Visual.stencilBits > 0)) {
 497       /* scissoring or we have a combined depth/stencil buffer */
 498       clear_with_quad(ctx, GL_FALSE, GL_TRUE, GL_FALSE);
 499    }
 500    else
 501 #endif
 502  {
 503       /* simple clear of whole buffer */
 504       GLuint clearValue = depth_value(strb->surface->format, ctx->Depth.Clear);
 505       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 506    }
 507 }
 508
 509
 510 static void
 511 clear_stencil_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 512 {
 513    struct st_renderbuffer *strb = st_renderbuffer(rb);
 514    const GLboolean isDS = is_depth_stencil_format(strb->surface->format);
 515    const GLuint stencilMax = (1 << rb->StencilBits) - 1;
 516    GLboolean maskStencil
 517       = (ctx->Stencil.WriteMask[0] & stencilMax) != stencilMax;
 518
 519    if (maskStencil ||
 520        ctx->Scissor.Enabled ||
 521        (isDS && ctx->DrawBuffer->Visual.depthBits > 0)) {
 522       /* masking or scissoring or combined depth/stencil buffer */
 523       clear_with_quad(ctx, GL_FALSE, GL_FALSE, GL_TRUE);
 524    }
 525    else {
 526       /* simple clear of whole buffer */
 527       GLuint clearValue = ctx->Stencil.Clear;
 528       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 529    }
 530 }
 531
 532
 533 static void
 534 clear_depth_stencil_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 535 {
 536    struct st_renderbuffer *strb = st_renderbuffer(rb);
 537    const GLuint stencilMax = (1 << rb->StencilBits) - 1;
 538    GLboolean maskStencil
 539       = (ctx->Stencil.WriteMask[0] & stencilMax) != stencilMax;
 540
 541    assert(is_depth_stencil_format(strb->surface->format));
 542
 543    if (!maskStencil && !ctx->Scissor.Enabled) {
 544       /* clear whole buffer w/out masking */
 545       GLuint clearValue = depth_value(strb->surface->format, ctx->Depth.Clear);
 546
 547       switch (strb->surface->format) {
 548       case PIPE_FORMAT_S8_Z24:
 549          clearValue |= ctx->Stencil.Clear << 24;
 550          break;
 551 #if 0
 552       case PIPE_FORMAT_Z24_S8:
 553          clearValue = (clearValue << 8) | clearVal;
 554          break;
 555 #endif
 556       default:
 557          assert(0);
 558       }
 559
 560       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 561    }
 562    else {
 563       /* masking or scissoring */
 564       clear_with_quad(ctx, GL_FALSE, GL_TRUE, GL_TRUE);
 565    }
 566 }
 567
 568
 569
 570 /**
 571  * Called via ctx->Driver.Clear()
 572  * XXX: doesn't pick up the differences between front/back/left/right
 573  * clears.  Need to sort that out...
 574  */
 575 static void st_clear(GLcontext *ctx, GLbitfield mask)
 576 {
 577    static const GLbitfield BUFFER_BITS_DS
 578       = (BUFFER_BIT_DEPTH | BUFFER_BIT_STENCIL);
 579    struct st_context *st = ctx->st;
 580    struct gl_renderbuffer *depthRb
 581       = ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
 582    struct gl_renderbuffer *stencilRb
 583       = ctx->DrawBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
 584    GLbitfield cmask = mask & BUFFER_BITS_COLOR;
 585
 586    /* This makes sure the softpipe has the latest scissor, etc values */
 587    st_validate_state( st );
 588
 589    /*
 590     * XXX TO-DO:
 591     * If we're going to use clear_with_quad() for any reason, use it to
 592     * clear as many other buffers as possible.
 593     * As it is now, we sometimes call clear_with_quad() three times to clear
 594     * color/depth/stencil individually...
 595     */
 596
 597    if (cmask) {
 598       GLuint b;
 599       for (b = 0; cmask; b++) {
 600          if (cmask & (1 << b)) {
 601             struct gl_renderbuffer *rb
 602                = ctx->DrawBuffer->Attachment[b].Renderbuffer;
 603             assert(rb);
 604             clear_color_buffer(ctx, rb);
 605             cmask &= ~(1 << b); /* turn off bit */
 606          }
 607          assert(b < BUFFER_COUNT);
 608       }
 609    }
 610
 611    if (mask & BUFFER_BIT_ACCUM) {
 612       clear_accum_buffer(ctx,
 613                      ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer);
 614    }
 615
 616    if ((mask & BUFFER_BITS_DS) == BUFFER_BITS_DS && depthRb == stencilRb) {
 617       /* clearing combined depth + stencil */
 618       clear_depth_stencil_buffer(ctx, depthRb);
 619    }
 620    else {
 621       /* separate depth/stencil clears */
 622       if (mask & BUFFER_BIT_DEPTH) {
 623          clear_depth_buffer(ctx, depthRb);
 624       }
 625       if (mask & BUFFER_BIT_STENCIL) {
 626          clear_stencil_buffer(ctx, stencilRb);
 627       }
 628    }
 629 }
 630
 631
 632 void st_init_clear_functions(struct dd_function_table *functions)
 633 {
 634    functions->Clear = st_clear;
 635 }