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       const struct cso_alpha_test *cso;
 279       memset(&alpha_test, 0, sizeof(alpha_test));
 280       cso = st_cached_alpha_test_state(st, &alpha_test);
 281       pipe->bind_alpha_test_state(pipe, cso->data);
 282    }
 283
 284    /* blend state: RGBA masking */
 285    {
 286       struct pipe_blend_state blend;
 287       const struct cso_blend *cso;
 288       memset(&blend, 0, sizeof(blend));
 289       if (color) {
 290          if (ctx->Color.ColorMask[0])
 291             blend.colormask |= PIPE_MASK_R;
 292          if (ctx->Color.ColorMask[1])
 293             blend.colormask |= PIPE_MASK_G;
 294          if (ctx->Color.ColorMask[2])
 295             blend.colormask |= PIPE_MASK_B;
 296          if (ctx->Color.ColorMask[3])
 297             blend.colormask |= PIPE_MASK_A;
 298          if (st->ctx->Color.DitherFlag)
 299             blend.dither = 1;
 300       }
 301       cso = st_cached_blend_state(st, &blend);
 302       pipe->bind_blend_state(pipe, cso->data);
 303    }
 304
 305    /* depth_stencil state: always pass/set to ref value */
 306    {
 307       struct pipe_depth_stencil_state depth_stencil;
 308       const struct cso_depth_stencil *cso;
 309       memset(&depth_stencil, 0, sizeof(depth_stencil));
 310       if (depth) {
 311          depth_stencil.depth.enabled = 1;
 312          depth_stencil.depth.writemask = 1;
 313          depth_stencil.depth.func = PIPE_FUNC_ALWAYS;
 314       }
 315
 316       if (stencil) {
 317          depth_stencil.stencil.front_enabled = 1;
 318          depth_stencil.stencil.front_func = PIPE_FUNC_ALWAYS;
 319          depth_stencil.stencil.front_fail_op = PIPE_STENCIL_OP_REPLACE;
 320          depth_stencil.stencil.front_zpass_op = PIPE_STENCIL_OP_REPLACE;
 321          depth_stencil.stencil.front_zfail_op = PIPE_STENCIL_OP_REPLACE;
 322          depth_stencil.stencil.ref_value[0] = ctx->Stencil.Clear;
 323          depth_stencil.stencil.value_mask[0] = 0xff;
 324          depth_stencil.stencil.write_mask[0] = ctx->Stencil.WriteMask[0] & 0xff;
 325       }
 326       cso = st_cached_depth_stencil_state(ctx->st, &depth_stencil);
 327       pipe->bind_depth_stencil_state(pipe, cso->data);
 328    }
 329
 330    /* setup state: nothing */
 331    {
 332       struct pipe_rasterizer_state raster;
 333       const struct cso_rasterizer *cso;
 334       memset(&raster, 0, sizeof(raster));
 335 #if 0
 336       /* don't do per-pixel scissor; we'll just draw a PIPE_PRIM_QUAD
 337        * that matches the scissor bounds.
 338        */
 339       if (ctx->Scissor.Enabled)
 340          raster.scissor = 1;
 341 #endif
 342       cso = st_cached_rasterizer_state(ctx->st, &raster);
 343       pipe->bind_rasterizer_state(pipe, cso->data);
 344    }
 345
 346    /* fragment shader state: color pass-through program */
 347    {
 348       static struct st_fragment_program *stfp = NULL;
 349       if (!stfp) {
 350          stfp = make_frag_shader(st);
 351       }
 352       pipe->bind_fs_state(pipe, stfp->fs->data);
 353    }
 354
 355    /* vertex shader state: color/position pass-through */
 356    {
 357       static struct st_vertex_program *stvp = NULL;
 358       if (!stvp) {
 359          stvp = make_vertex_shader(st);
 360       }
 361       pipe->bind_vs_state(pipe, stvp->vs->data);
 362    }
 363
 364    /* viewport state: viewport matching window dims */
 365    {
 366       const float width = ctx->DrawBuffer->Width;
 367       const float height = ctx->DrawBuffer->Height;
 368       struct pipe_viewport_state vp;
 369       vp.scale[0] =  0.5 * width;
 370       vp.scale[1] = -0.5 * height;
 371       vp.scale[2] = 0.5;
 372       vp.scale[3] = 1.0;
 373       vp.translate[0] = 0.5 * width;
 374       vp.translate[1] = 0.5 * height;
 375       vp.translate[2] = 0.5;
 376       vp.translate[3] = 0.0;
 377       pipe->set_viewport_state(pipe, &vp);
 378    }
 379
 380    /* draw quad matching scissor rect (XXX verify coord round-off) */
 381    draw_quad(ctx, x0, y0, x1, y1, ctx->Depth.Clear, ctx->Color.ClearColor);
 382
 383    /* Restore pipe state */
 384    pipe->bind_alpha_test_state(pipe, st->state.alpha_test->data);
 385    pipe->bind_blend_state(pipe, st->state.blend->data);
 386    pipe->bind_depth_stencil_state(pipe, st->state.depth_stencil->data);
 387    pipe->bind_fs_state(pipe, st->state.fs->data);
 388    pipe->bind_vs_state(pipe, st->state.vs->data);
 389    pipe->bind_rasterizer_state(pipe, st->state.rasterizer->data);
 390    pipe->set_viewport_state(pipe, &ctx->st->state.viewport);
 391    /* OR:
 392    st_invalidate_state(ctx, _NEW_COLOR | _NEW_DEPTH | _NEW_STENCIL);
 393    */
 394 }
 395
 396
 397 /**
 398  * Determine if we need to clear the depth buffer by drawing a quad.
 399  */
 400 static INLINE GLboolean
 401 check_clear_color_with_quad(GLcontext *ctx)
 402 {
 403    return !(ctx->Color.ColorMask[0] &&
 404             ctx->Color.ColorMask[1] &&
 405             ctx->Color.ColorMask[2] &&
 406             ctx->Color.ColorMask[3] &&
 407             !ctx->Scissor.Enabled);
 408 }
 409
 410
 411 /**
 412  * Determine if we need to clear the depth buffer by drawing a quad.
 413  */
 414 static INLINE GLboolean
 415 check_clear_depth_with_quad(GLcontext *ctx, struct gl_renderbuffer *rb)
 416 {
 417    const struct st_renderbuffer *strb = st_renderbuffer(rb);
 418    const GLboolean isDS = is_depth_stencil_format(strb->surface->format);
 419    return  ctx->Scissor.Enabled
 420       || (isDS && ctx->DrawBuffer->Visual.stencilBits > 0);
 421 }
 422
 423
 424 /**
 425  * Determine if we need to clear the stencil buffer by drawing a quad.
 426  */
 427 static INLINE GLboolean
 428 check_clear_stencil_with_quad(GLcontext *ctx, struct gl_renderbuffer *rb)
 429 {
 430    const struct st_renderbuffer *strb = st_renderbuffer(rb);
 431    const GLboolean isDS = is_depth_stencil_format(strb->surface->format);
 432    const GLuint stencilMax = (1 << rb->StencilBits) - 1;
 433    const GLboolean maskStencil
 434       = (ctx->Stencil.WriteMask[0] & stencilMax) != stencilMax;
 435    return maskStencil
 436       || ctx->Scissor.Enabled
 437       || (isDS && ctx->DrawBuffer->Visual.depthBits > 0);
 438 }
 439
 440
 441
 442
 443 static void
 444 clear_color_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 445 {
 446    struct st_renderbuffer *strb = st_renderbuffer(rb);
 447
 448    if (ctx->Color.ColorMask[0] &&
 449        ctx->Color.ColorMask[1] &&
 450        ctx->Color.ColorMask[2] &&
 451        ctx->Color.ColorMask[3] &&
 452        !ctx->Scissor.Enabled)
 453    {
 454       /* clear whole buffer w/out masking */
 455       GLuint clearValue
 456          = color_value(strb->surface->format, ctx->Color.ClearColor);
 457       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 458    }
 459    else {
 460       /* masking or scissoring */
 461       clear_with_quad(ctx, GL_TRUE, GL_FALSE, GL_FALSE);
 462    }
 463 }
 464
 465
 466 static void
 467 clear_accum_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 468 {
 469    struct st_renderbuffer *strb = st_renderbuffer(rb);
 470
 471    if (!ctx->Scissor.Enabled) {
 472       /* clear whole buffer w/out masking */
 473       GLuint clearValue
 474          = color_value(strb->surface->format, ctx->Accum.ClearColor);
 475       /* Note that clearValue is 32 bits but the accum buffer will
 476        * typically be 64bpp...
 477        */
 478       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 479    }
 480    else {
 481       /* scissoring */
 482       /* XXX point framebuffer.cbufs[0] at the accum buffer */
 483       clear_with_quad(ctx, GL_TRUE, GL_FALSE, GL_FALSE);
 484    }
 485 }
 486
 487
 488 static void
 489 clear_depth_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 490 {
 491    struct st_renderbuffer *strb = st_renderbuffer(rb);
 492    const GLboolean isDS = is_depth_stencil_format(strb->surface->format);
 493
 494    assert(strb->surface->format);
 495
 496    if (ctx->Scissor.Enabled ||
 497        (isDS && ctx->DrawBuffer->Visual.stencilBits > 0)) {
 498       /* scissoring or we have a combined depth/stencil buffer */
 499       clear_with_quad(ctx, GL_FALSE, GL_TRUE, GL_FALSE);
 500    }
 501    else {
 502       /* simple clear of whole buffer */
 503       GLuint clearValue = depth_value(strb->surface->format, ctx->Depth.Clear);
 504       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 505    }
 506 }
 507
 508
 509 static void
 510 clear_stencil_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 511 {
 512    struct st_renderbuffer *strb = st_renderbuffer(rb);
 513    const GLboolean isDS = is_depth_stencil_format(strb->surface->format);
 514    const GLuint stencilMax = (1 << rb->StencilBits) - 1;
 515    GLboolean maskStencil
 516       = (ctx->Stencil.WriteMask[0] & stencilMax) != stencilMax;
 517
 518    if (maskStencil ||
 519        ctx->Scissor.Enabled ||
 520        (isDS && ctx->DrawBuffer->Visual.depthBits > 0)) {
 521       /* masking or scissoring or combined depth/stencil buffer */
 522       clear_with_quad(ctx, GL_FALSE, GL_FALSE, GL_TRUE);
 523    }
 524    else {
 525       /* simple clear of whole buffer */
 526       GLuint clearValue = ctx->Stencil.Clear;
 527       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 528    }
 529 }
 530
 531
 532 static void
 533 clear_depth_stencil_buffer(GLcontext *ctx, struct gl_renderbuffer *rb)
 534 {
 535    struct st_renderbuffer *strb = st_renderbuffer(rb);
 536    const GLuint stencilMax = (1 << rb->StencilBits) - 1;
 537    GLboolean maskStencil
 538       = (ctx->Stencil.WriteMask[0] & stencilMax) != stencilMax;
 539
 540    assert(is_depth_stencil_format(strb->surface->format));
 541
 542    if (!maskStencil && !ctx->Scissor.Enabled) {
 543       /* clear whole buffer w/out masking */
 544       GLuint clearValue = depth_value(strb->surface->format, ctx->Depth.Clear);
 545
 546       switch (strb->surface->format) {
 547       case PIPE_FORMAT_S8_Z24:
 548          clearValue |= ctx->Stencil.Clear << 24;
 549          break;
 550 #if 0
 551       case PIPE_FORMAT_Z24_S8:
 552          clearValue = (clearValue << 8) | clearVal;
 553          break;
 554 #endif
 555       default:
 556          assert(0);
 557       }
 558
 559       ctx->st->pipe->clear(ctx->st->pipe, strb->surface, clearValue);
 560    }
 561    else {
 562       /* masking or scissoring */
 563       clear_with_quad(ctx, GL_FALSE, GL_TRUE, GL_TRUE);
 564    }
 565 }
 566
 567
 568
 569 /**
 570  * Called via ctx->Driver.Clear()
 571  * XXX: doesn't pick up the differences between front/back/left/right
 572  * clears.  Need to sort that out...
 573  */
 574 static void st_clear(GLcontext *ctx, GLbitfield mask)
 575 {
 576    static const GLbitfield BUFFER_BITS_DS
 577       = (BUFFER_BIT_DEPTH | BUFFER_BIT_STENCIL);
 578    struct st_context *st = ctx->st;
 579    struct gl_renderbuffer *depthRb
 580       = ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
 581    struct gl_renderbuffer *stencilRb
 582       = ctx->DrawBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
 583    GLbitfield cmask = mask & BUFFER_BITS_COLOR;
 584
 585    /* This makes sure the softpipe has the latest scissor, etc values */
 586    st_validate_state( st );
 587
 588    /*
 589     * XXX TO-DO:
 590     * If we're going to use clear_with_quad() for any reason, use it to
 591     * clear as many other buffers as possible.
 592     * As it is now, we sometimes call clear_with_quad() three times to clear
 593     * color/depth/stencil individually...
 594     */
 595
 596    if (cmask) {
 597       GLuint b;
 598       for (b = 0; cmask; b++) {
 599          if (cmask & (1 << b)) {
 600             struct gl_renderbuffer *rb
 601                = ctx->DrawBuffer->Attachment[b].Renderbuffer;
 602             assert(rb);
 603             clear_color_buffer(ctx, rb);
 604             cmask &= ~(1 << b); /* turn off bit */
 605          }
 606          assert(b < BUFFER_COUNT);
 607       }
 608    }
 609
 610    if (mask & BUFFER_BIT_ACCUM) {
 611       clear_accum_buffer(ctx,
 612                      ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer);
 613    }
 614
 615    if ((mask & BUFFER_BITS_DS) == BUFFER_BITS_DS && depthRb == stencilRb) {
 616       /* clearing combined depth + stencil */
 617       clear_depth_stencil_buffer(ctx, depthRb);
 618    }
 619    else {
 620       /* separate depth/stencil clears */
 621       if (mask & BUFFER_BIT_DEPTH) {
 622          clear_depth_buffer(ctx, depthRb);
 623       }
 624       if (mask & BUFFER_BIT_STENCIL) {
 625          clear_stencil_buffer(ctx, stencilRb);
 626       }
 627    }
 628 }
 629
 630
 631 void st_init_clear_functions(struct dd_function_table *functions)
 632 {
 633    functions->Clear = st_clear;
 634 }