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      1 /**************************************************************************
      2  *
      3  * Copyright 2003 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 #include <sys/errno.h>
     29 
     30 #include "main/glheader.h"
     31 #include "main/context.h"
     32 #include "main/condrender.h"
     33 #include "main/samplerobj.h"
     34 #include "main/state.h"
     35 #include "main/enums.h"
     36 #include "main/macros.h"
     37 #include "tnl/tnl.h"
     38 #include "vbo/vbo_context.h"
     39 #include "swrast/swrast.h"
     40 #include "swrast_setup/swrast_setup.h"
     41 #include "drivers/common/meta.h"
     42 
     43 #include "brw_draw.h"
     44 #include "brw_defines.h"
     45 #include "brw_context.h"
     46 #include "brw_state.h"
     47 
     48 #include "intel_batchbuffer.h"
     49 #include "intel_fbo.h"
     50 #include "intel_mipmap_tree.h"
     51 #include "intel_regions.h"
     52 
     53 #define FILE_DEBUG_FLAG DEBUG_PRIMS
     54 
     55 static GLuint prim_to_hw_prim[GL_POLYGON+1] = {
     56    _3DPRIM_POINTLIST,
     57    _3DPRIM_LINELIST,
     58    _3DPRIM_LINELOOP,
     59    _3DPRIM_LINESTRIP,
     60    _3DPRIM_TRILIST,
     61    _3DPRIM_TRISTRIP,
     62    _3DPRIM_TRIFAN,
     63    _3DPRIM_QUADLIST,
     64    _3DPRIM_QUADSTRIP,
     65    _3DPRIM_POLYGON
     66 };
     67 
     68 
     69 static const GLenum reduced_prim[GL_POLYGON+1] = {
     70    GL_POINTS,
     71    GL_LINES,
     72    GL_LINES,
     73    GL_LINES,
     74    GL_TRIANGLES,
     75    GL_TRIANGLES,
     76    GL_TRIANGLES,
     77    GL_TRIANGLES,
     78    GL_TRIANGLES,
     79    GL_TRIANGLES
     80 };
     81 
     82 
     83 /* When the primitive changes, set a state bit and re-validate.  Not
     84  * the nicest and would rather deal with this by having all the
     85  * programs be immune to the active primitive (ie. cope with all
     86  * possibilities).  That may not be realistic however.
     87  */
     88 static void brw_set_prim(struct brw_context *brw,
     89                          const struct _mesa_prim *prim)
     90 {
     91    struct gl_context *ctx = &brw->intel.ctx;
     92    uint32_t hw_prim = prim_to_hw_prim[prim->mode];
     93 
     94    DBG("PRIM: %s\n", _mesa_lookup_enum_by_nr(prim->mode));
     95 
     96    /* Slight optimization to avoid the GS program when not needed:
     97     */
     98    if (prim->mode == GL_QUAD_STRIP &&
     99        ctx->Light.ShadeModel != GL_FLAT &&
    100        ctx->Polygon.FrontMode == GL_FILL &&
    101        ctx->Polygon.BackMode == GL_FILL)
    102       hw_prim = _3DPRIM_TRISTRIP;
    103 
    104    if (prim->mode == GL_QUADS && prim->count == 4 &&
    105        ctx->Light.ShadeModel != GL_FLAT &&
    106        ctx->Polygon.FrontMode == GL_FILL &&
    107        ctx->Polygon.BackMode == GL_FILL) {
    108       hw_prim = _3DPRIM_TRIFAN;
    109    }
    110 
    111    if (hw_prim != brw->primitive) {
    112       brw->primitive = hw_prim;
    113       brw->state.dirty.brw |= BRW_NEW_PRIMITIVE;
    114 
    115       if (reduced_prim[prim->mode] != brw->intel.reduced_primitive) {
    116 	 brw->intel.reduced_primitive = reduced_prim[prim->mode];
    117 	 brw->state.dirty.brw |= BRW_NEW_REDUCED_PRIMITIVE;
    118       }
    119    }
    120 }
    121 
    122 static void gen6_set_prim(struct brw_context *brw,
    123                           const struct _mesa_prim *prim)
    124 {
    125    uint32_t hw_prim;
    126 
    127    DBG("PRIM: %s\n", _mesa_lookup_enum_by_nr(prim->mode));
    128 
    129    hw_prim = prim_to_hw_prim[prim->mode];
    130 
    131    if (hw_prim != brw->primitive) {
    132       brw->primitive = hw_prim;
    133       brw->state.dirty.brw |= BRW_NEW_PRIMITIVE;
    134    }
    135 }
    136 
    137 
    138 static GLuint trim(GLenum prim, GLuint length)
    139 {
    140    if (prim == GL_QUAD_STRIP)
    141       return length > 3 ? (length - length % 2) : 0;
    142    else if (prim == GL_QUADS)
    143       return length - length % 4;
    144    else
    145       return length;
    146 }
    147 
    148 
    149 static void brw_emit_prim(struct brw_context *brw,
    150 			  const struct _mesa_prim *prim,
    151 			  uint32_t hw_prim)
    152 {
    153    struct intel_context *intel = &brw->intel;
    154    int verts_per_instance;
    155    int vertex_access_type;
    156    int start_vertex_location;
    157    int base_vertex_location;
    158 
    159    DBG("PRIM: %s %d %d\n", _mesa_lookup_enum_by_nr(prim->mode),
    160        prim->start, prim->count);
    161 
    162    start_vertex_location = prim->start;
    163    base_vertex_location = prim->basevertex;
    164    if (prim->indexed) {
    165       vertex_access_type = GEN4_3DPRIM_VERTEXBUFFER_ACCESS_RANDOM;
    166       start_vertex_location += brw->ib.start_vertex_offset;
    167       base_vertex_location += brw->vb.start_vertex_bias;
    168    } else {
    169       vertex_access_type = GEN4_3DPRIM_VERTEXBUFFER_ACCESS_SEQUENTIAL;
    170       start_vertex_location += brw->vb.start_vertex_bias;
    171    }
    172 
    173    verts_per_instance = trim(prim->mode, prim->count);
    174 
    175    /* If nothing to emit, just return. */
    176    if (verts_per_instance == 0)
    177       return;
    178 
    179    /* If we're set to always flush, do it before and after the primitive emit.
    180     * We want to catch both missed flushes that hurt instruction/state cache
    181     * and missed flushes of the render cache as it heads to other parts of
    182     * the besides the draw code.
    183     */
    184    if (intel->always_flush_cache) {
    185       intel_batchbuffer_emit_mi_flush(intel);
    186    }
    187 
    188    BEGIN_BATCH(6);
    189    OUT_BATCH(CMD_3D_PRIM << 16 | (6 - 2) |
    190 	     hw_prim << GEN4_3DPRIM_TOPOLOGY_TYPE_SHIFT |
    191 	     vertex_access_type);
    192    OUT_BATCH(verts_per_instance);
    193    OUT_BATCH(start_vertex_location);
    194    OUT_BATCH(prim->num_instances);
    195    OUT_BATCH(0); // start instance location
    196    OUT_BATCH(base_vertex_location);
    197    ADVANCE_BATCH();
    198 
    199    intel->batch.need_workaround_flush = true;
    200 
    201    if (intel->always_flush_cache) {
    202       intel_batchbuffer_emit_mi_flush(intel);
    203    }
    204 }
    205 
    206 static void gen7_emit_prim(struct brw_context *brw,
    207 			   const struct _mesa_prim *prim,
    208 			   uint32_t hw_prim)
    209 {
    210    struct intel_context *intel = &brw->intel;
    211    int verts_per_instance;
    212    int vertex_access_type;
    213    int start_vertex_location;
    214    int base_vertex_location;
    215 
    216    DBG("PRIM: %s %d %d\n", _mesa_lookup_enum_by_nr(prim->mode),
    217        prim->start, prim->count);
    218 
    219    start_vertex_location = prim->start;
    220    base_vertex_location = prim->basevertex;
    221    if (prim->indexed) {
    222       vertex_access_type = GEN7_3DPRIM_VERTEXBUFFER_ACCESS_RANDOM;
    223       start_vertex_location += brw->ib.start_vertex_offset;
    224       base_vertex_location += brw->vb.start_vertex_bias;
    225    } else {
    226       vertex_access_type = GEN7_3DPRIM_VERTEXBUFFER_ACCESS_SEQUENTIAL;
    227       start_vertex_location += brw->vb.start_vertex_bias;
    228    }
    229 
    230    verts_per_instance = trim(prim->mode, prim->count);
    231 
    232    /* If nothing to emit, just return. */
    233    if (verts_per_instance == 0)
    234       return;
    235 
    236    /* If we're set to always flush, do it before and after the primitive emit.
    237     * We want to catch both missed flushes that hurt instruction/state cache
    238     * and missed flushes of the render cache as it heads to other parts of
    239     * the besides the draw code.
    240     */
    241    if (intel->always_flush_cache) {
    242       intel_batchbuffer_emit_mi_flush(intel);
    243    }
    244 
    245    BEGIN_BATCH(7);
    246    OUT_BATCH(CMD_3D_PRIM << 16 | (7 - 2));
    247    OUT_BATCH(hw_prim | vertex_access_type);
    248    OUT_BATCH(verts_per_instance);
    249    OUT_BATCH(start_vertex_location);
    250    OUT_BATCH(prim->num_instances);
    251    OUT_BATCH(0); // start instance location
    252    OUT_BATCH(base_vertex_location);
    253    ADVANCE_BATCH();
    254 
    255    if (intel->always_flush_cache) {
    256       intel_batchbuffer_emit_mi_flush(intel);
    257    }
    258 }
    259 
    260 
    261 static void brw_merge_inputs( struct brw_context *brw,
    262 		       const struct gl_client_array *arrays[])
    263 {
    264    struct brw_vertex_info old = brw->vb.info;
    265    GLuint i;
    266 
    267    for (i = 0; i < brw->vb.nr_buffers; i++) {
    268       drm_intel_bo_unreference(brw->vb.buffers[i].bo);
    269       brw->vb.buffers[i].bo = NULL;
    270    }
    271    brw->vb.nr_buffers = 0;
    272 
    273    memset(&brw->vb.info, 0, sizeof(brw->vb.info));
    274 
    275    for (i = 0; i < VERT_ATTRIB_MAX; i++) {
    276       brw->vb.inputs[i].buffer = -1;
    277       brw->vb.inputs[i].glarray = arrays[i];
    278       brw->vb.inputs[i].attrib = (gl_vert_attrib) i;
    279 
    280       if (arrays[i]->StrideB != 0)
    281 	 brw->vb.info.sizes[i/16] |= (brw->vb.inputs[i].glarray->Size - 1) <<
    282 	    ((i%16) * 2);
    283    }
    284 
    285    /* Raise statechanges if input sizes have changed. */
    286    if (memcmp(brw->vb.info.sizes, old.sizes, sizeof(old.sizes)) != 0)
    287       brw->state.dirty.brw |= BRW_NEW_INPUT_DIMENSIONS;
    288 }
    289 
    290 /*
    291  * \brief Resolve buffers before drawing.
    292  *
    293  * Resolve the depth buffer's HiZ buffer and resolve the depth buffer of each
    294  * enabled depth texture.
    295  *
    296  * (In the future, this will also perform MSAA resolves).
    297  */
    298 static void
    299 brw_predraw_resolve_buffers(struct brw_context *brw)
    300 {
    301    struct gl_context *ctx = &brw->intel.ctx;
    302    struct intel_context *intel = &brw->intel;
    303    struct intel_renderbuffer *depth_irb;
    304    struct intel_texture_object *tex_obj;
    305 
    306    /* Resolve the depth buffer's HiZ buffer. */
    307    depth_irb = intel_get_renderbuffer(ctx->DrawBuffer, BUFFER_DEPTH);
    308    if (depth_irb)
    309       intel_renderbuffer_resolve_hiz(intel, depth_irb);
    310 
    311    /* Resolve depth buffer of each enabled depth texture. */
    312    for (int i = 0; i < BRW_MAX_TEX_UNIT; i++) {
    313       if (!ctx->Texture.Unit[i]._ReallyEnabled)
    314 	 continue;
    315       tex_obj = intel_texture_object(ctx->Texture.Unit[i]._Current);
    316       if (!tex_obj || !tex_obj->mt)
    317 	 continue;
    318       intel_miptree_all_slices_resolve_depth(intel, tex_obj->mt);
    319    }
    320 }
    321 
    322 /**
    323  * \brief Call this after drawing to mark which buffers need resolving
    324  *
    325  * If the depth buffer was written to and if it has an accompanying HiZ
    326  * buffer, then mark that it needs a depth resolve.
    327  *
    328  * If the color buffer is a multisample window system buffer, then
    329  * mark that it needs a downsample.
    330  */
    331 static void brw_postdraw_set_buffers_need_resolve(struct brw_context *brw)
    332 {
    333    struct intel_context *intel = &brw->intel;
    334    struct gl_context *ctx = &brw->intel.ctx;
    335    struct gl_framebuffer *fb = ctx->DrawBuffer;
    336 
    337    struct intel_renderbuffer *front_irb = NULL;
    338    struct intel_renderbuffer *back_irb = intel_get_renderbuffer(fb, BUFFER_BACK_LEFT);
    339    struct intel_renderbuffer *depth_irb = intel_get_renderbuffer(fb, BUFFER_DEPTH);
    340 
    341    if (intel->is_front_buffer_rendering)
    342       front_irb = intel_get_renderbuffer(fb, BUFFER_FRONT_LEFT);
    343 
    344    if (front_irb)
    345       intel_renderbuffer_set_needs_downsample(front_irb);
    346    if (back_irb)
    347       intel_renderbuffer_set_needs_downsample(back_irb);
    348    if (depth_irb && ctx->Depth.Mask)
    349       intel_renderbuffer_set_needs_depth_resolve(depth_irb);
    350 }
    351 
    352 static int
    353 verts_per_prim(GLenum mode)
    354 {
    355    switch (mode) {
    356    case GL_POINTS:
    357       return 1;
    358    case GL_LINE_STRIP:
    359    case GL_LINE_LOOP:
    360    case GL_LINES:
    361       return 2;
    362    case GL_TRIANGLE_STRIP:
    363    case GL_TRIANGLE_FAN:
    364    case GL_POLYGON:
    365    case GL_TRIANGLES:
    366    case GL_QUADS:
    367    case GL_QUAD_STRIP:
    368       return 3;
    369    default:
    370       _mesa_problem(NULL,
    371 		    "unknown prim type in transform feedback primitive count");
    372       return 0;
    373    }
    374 }
    375 
    376 /**
    377  * Update internal counters based on the the drawing operation described in
    378  * prim.
    379  */
    380 static void
    381 brw_update_primitive_count(struct brw_context *brw,
    382                            const struct _mesa_prim *prim)
    383 {
    384    uint32_t count = count_tessellated_primitives(prim);
    385    brw->sol.primitives_generated += count;
    386    if (brw->intel.ctx.TransformFeedback.CurrentObject->Active &&
    387        !brw->intel.ctx.TransformFeedback.CurrentObject->Paused) {
    388       /* Update brw->sol.svbi_0_max_index to reflect the amount by which the
    389        * hardware is going to increment SVBI 0 when this drawing operation
    390        * occurs.  This is necessary because the kernel does not (yet) save and
    391        * restore GPU registers when context switching, so we'll need to be
    392        * able to reload SVBI 0 with the correct value in case we have to start
    393        * a new batch buffer.
    394        */
    395       unsigned verts = verts_per_prim(prim->mode);
    396       uint32_t space_avail =
    397          (brw->sol.svbi_0_max_index - brw->sol.svbi_0_starting_index) / verts;
    398       uint32_t primitives_written = MIN2 (space_avail, count);
    399       brw->sol.svbi_0_starting_index += verts * primitives_written;
    400 
    401       /* And update the TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN query. */
    402       brw->sol.primitives_written += primitives_written;
    403    }
    404 }
    405 
    406 /* May fail if out of video memory for texture or vbo upload, or on
    407  * fallback conditions.
    408  */
    409 static bool brw_try_draw_prims( struct gl_context *ctx,
    410 				     const struct gl_client_array *arrays[],
    411 				     const struct _mesa_prim *prim,
    412 				     GLuint nr_prims,
    413 				     const struct _mesa_index_buffer *ib,
    414 				     GLuint min_index,
    415 				     GLuint max_index )
    416 {
    417    struct intel_context *intel = intel_context(ctx);
    418    struct brw_context *brw = brw_context(ctx);
    419    bool retval = true;
    420    GLuint i;
    421    bool fail_next = false;
    422 
    423    if (ctx->NewState)
    424       _mesa_update_state( ctx );
    425 
    426    /* We have to validate the textures *before* checking for fallbacks;
    427     * otherwise, the software fallback won't be able to rely on the
    428     * texture state, the firstLevel and lastLevel fields won't be
    429     * set in the intel texture object (they'll both be 0), and the
    430     * software fallback will segfault if it attempts to access any
    431     * texture level other than level 0.
    432     */
    433    brw_validate_textures( brw );
    434 
    435    intel_prepare_render(intel);
    436 
    437    /* Resolves must occur after updating renderbuffers, updating context state,
    438     * and finalizing textures but before setting up any hardware state for
    439     * this draw call.
    440     */
    441    brw_predraw_resolve_buffers(brw);
    442 
    443    /* Bind all inputs, derive varying and size information:
    444     */
    445    brw_merge_inputs( brw, arrays );
    446 
    447    brw->ib.ib = ib;
    448    brw->state.dirty.brw |= BRW_NEW_INDICES;
    449 
    450    brw->vb.min_index = min_index;
    451    brw->vb.max_index = max_index;
    452    brw->state.dirty.brw |= BRW_NEW_VERTICES;
    453 
    454    /* Have to validate state quite late.  Will rebuild tnl_program,
    455     * which depends on varying information.
    456     *
    457     * Note this is where brw->vs->prog_data.inputs_read is calculated,
    458     * so can't access it earlier.
    459     */
    460 
    461    for (i = 0; i < nr_prims; i++) {
    462       int estimated_max_prim_size;
    463 
    464       estimated_max_prim_size = 512; /* batchbuffer commands */
    465       estimated_max_prim_size += (BRW_MAX_TEX_UNIT *
    466 				  (sizeof(struct brw_sampler_state) +
    467 				   sizeof(struct gen5_sampler_default_color)));
    468       estimated_max_prim_size += 1024; /* gen6 VS push constants */
    469       estimated_max_prim_size += 1024; /* gen6 WM push constants */
    470       estimated_max_prim_size += 512; /* misc. pad */
    471 
    472       /* Flush the batch if it's approaching full, so that we don't wrap while
    473        * we've got validated state that needs to be in the same batch as the
    474        * primitives.
    475        */
    476       intel_batchbuffer_require_space(intel, estimated_max_prim_size, false);
    477       intel_batchbuffer_save_state(intel);
    478 
    479       brw->num_instances = prim->num_instances;
    480       if (intel->gen < 6)
    481 	 brw_set_prim(brw, &prim[i]);
    482       else
    483 	 gen6_set_prim(brw, &prim[i]);
    484 
    485 retry:
    486       /* Note that before the loop, brw->state.dirty.brw was set to != 0, and
    487        * that the state updated in the loop outside of this block is that in
    488        * *_set_prim or intel_batchbuffer_flush(), which only impacts
    489        * brw->state.dirty.brw.
    490        */
    491       if (brw->state.dirty.brw) {
    492 	 intel->no_batch_wrap = true;
    493 	 brw_upload_state(brw);
    494       }
    495 
    496       if (intel->gen >= 7)
    497 	 gen7_emit_prim(brw, &prim[i], brw->primitive);
    498       else
    499 	 brw_emit_prim(brw, &prim[i], brw->primitive);
    500 
    501       intel->no_batch_wrap = false;
    502 
    503       if (dri_bufmgr_check_aperture_space(&intel->batch.bo, 1)) {
    504 	 if (!fail_next) {
    505 	    intel_batchbuffer_reset_to_saved(intel);
    506 	    intel_batchbuffer_flush(intel);
    507 	    fail_next = true;
    508 	    goto retry;
    509 	 } else {
    510 	    if (intel_batchbuffer_flush(intel) == -ENOSPC) {
    511 	       static bool warned = false;
    512 
    513 	       if (!warned) {
    514 		  fprintf(stderr, "i965: Single primitive emit exceeded"
    515 			  "available aperture space\n");
    516 		  warned = true;
    517 	       }
    518 
    519 	       retval = false;
    520 	    }
    521 	 }
    522       }
    523 
    524       if (!_mesa_meta_in_progress(ctx))
    525          brw_update_primitive_count(brw, &prim[i]);
    526    }
    527 
    528    if (intel->always_flush_batch)
    529       intel_batchbuffer_flush(intel);
    530 
    531    brw_state_cache_check_size(brw);
    532    brw_postdraw_set_buffers_need_resolve(brw);
    533 
    534    return retval;
    535 }
    536 
    537 void brw_draw_prims( struct gl_context *ctx,
    538 		     const struct _mesa_prim *prim,
    539 		     GLuint nr_prims,
    540 		     const struct _mesa_index_buffer *ib,
    541 		     GLboolean index_bounds_valid,
    542 		     GLuint min_index,
    543 		     GLuint max_index,
    544 		     struct gl_transform_feedback_object *tfb_vertcount )
    545 {
    546    const struct gl_client_array **arrays = ctx->Array._DrawArrays;
    547 
    548    if (!_mesa_check_conditional_render(ctx))
    549       return;
    550 
    551    /* Handle primitive restart if needed */
    552    if (brw_handle_primitive_restart(ctx, prim, nr_prims, ib)) {
    553       /* The draw was handled, so we can exit now */
    554       return;
    555    }
    556 
    557    if (!vbo_all_varyings_in_vbos(arrays)) {
    558       if (!index_bounds_valid)
    559 	 vbo_get_minmax_indices(ctx, prim, ib, &min_index, &max_index, nr_prims);
    560 
    561       /* Decide if we want to rebase.  If so we end up recursing once
    562        * only into this function.
    563        */
    564       if (min_index != 0 && !vbo_any_varyings_in_vbos(arrays)) {
    565 	 vbo_rebase_prims(ctx, arrays,
    566 			  prim, nr_prims,
    567 			  ib, min_index, max_index,
    568 			  brw_draw_prims );
    569 	 return;
    570       }
    571    }
    572 
    573    /* Do GL_SELECT and GL_FEEDBACK rendering using swrast, even though it
    574     * won't support all the extensions we support.
    575     */
    576    if (ctx->RenderMode != GL_RENDER) {
    577       perf_debug("%s render mode not supported in hardware\n",
    578                  _mesa_lookup_enum_by_nr(ctx->RenderMode));
    579       _swsetup_Wakeup(ctx);
    580       _tnl_wakeup(ctx);
    581       _tnl_draw_prims(ctx, arrays, prim, nr_prims, ib, min_index, max_index);
    582       return;
    583    }
    584 
    585    /* Try drawing with the hardware, but don't do anything else if we can't
    586     * manage it.  swrast doesn't support our featureset, so we can't fall back
    587     * to it.
    588     */
    589    brw_try_draw_prims(ctx, arrays, prim, nr_prims, ib, min_index, max_index);
    590 }
    591 
    592 void brw_draw_init( struct brw_context *brw )
    593 {
    594    struct gl_context *ctx = &brw->intel.ctx;
    595    struct vbo_context *vbo = vbo_context(ctx);
    596    int i;
    597 
    598    /* Register our drawing function:
    599     */
    600    vbo->draw_prims = brw_draw_prims;
    601 
    602    for (i = 0; i < VERT_ATTRIB_MAX; i++)
    603       brw->vb.inputs[i].buffer = -1;
    604    brw->vb.nr_buffers = 0;
    605    brw->vb.nr_enabled = 0;
    606 }
    607 
    608 void brw_draw_destroy( struct brw_context *brw )
    609 {
    610    int i;
    611 
    612    for (i = 0; i < brw->vb.nr_buffers; i++) {
    613       drm_intel_bo_unreference(brw->vb.buffers[i].bo);
    614       brw->vb.buffers[i].bo = NULL;
    615    }
    616    brw->vb.nr_buffers = 0;
    617 
    618    for (i = 0; i < brw->vb.nr_enabled; i++) {
    619       brw->vb.enabled[i]->buffer = -1;
    620    }
    621    brw->vb.nr_enabled = 0;
    622 
    623    drm_intel_bo_unreference(brw->ib.bo);
    624    brw->ib.bo = NULL;
    625 }
    626