src/mesa/drivers/dri/i965/gen6_clip_state.c

   1 /*
   2  * Copyright © 2009 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  * Authors:
  24  *    Eric Anholt <eric@anholt.net>
  25  *
  26  */
  27
  28 #include "brw_context.h"
  29 #include "brw_state.h"
  30 #include "brw_defines.h"
  31 #include "brw_util.h"
  32 #include "intel_batchbuffer.h"
  33 #include "main/fbobject.h"
  34 #include "main/framebuffer.h"
  35
  36 bool
  37 brw_is_drawing_points(const struct brw_context *brw)
  38 {
  39    /* Determine if the primitives *reaching the SF* are points */
  40    /* _NEW_POLYGON */
  41    if (brw->ctx.Polygon.FrontMode == GL_POINT ||
  42        brw->ctx.Polygon.BackMode == GL_POINT) {
  43       return true;
  44    }
  45
  46    if (brw->gs.base.prog_data) {
  47       /* BRW_NEW_GS_PROG_DATA */
  48       return brw_gs_prog_data(brw->gs.base.prog_data)->output_topology ==
  49              _3DPRIM_POINTLIST;
  50    } else if (brw->tes.base.prog_data) {
  51       /* BRW_NEW_TES_PROG_DATA */
  52       return brw_tes_prog_data(brw->tes.base.prog_data)->output_topology ==
  53              BRW_TESS_OUTPUT_TOPOLOGY_POINT;
  54    } else {
  55       /* BRW_NEW_PRIMITIVE */
  56       return brw->primitive == _3DPRIM_POINTLIST;
  57    }
  58 }
  59
  60 bool
  61 brw_is_drawing_lines(const struct brw_context *brw)
  62 {
  63    /* Determine if the primitives *reaching the SF* are points */
  64    /* _NEW_POLYGON */
  65    if (brw->ctx.Polygon.FrontMode == GL_LINE ||
  66        brw->ctx.Polygon.BackMode == GL_LINE) {
  67       return true;
  68    }
  69
  70    if (brw->gs.base.prog_data) {
  71       /* BRW_NEW_GS_PROG_DATA */
  72       return brw_gs_prog_data(brw->gs.base.prog_data)->output_topology ==
  73              _3DPRIM_LINESTRIP;
  74    } else if (brw->tes.base.prog_data) {
  75       /* BRW_NEW_TES_PROG_DATA */
  76       return brw_tes_prog_data(brw->tes.base.prog_data)->output_topology ==
  77              BRW_TESS_OUTPUT_TOPOLOGY_LINE;
  78    } else {
  79       /* BRW_NEW_PRIMITIVE */
  80       switch (brw->primitive) {
  81       case _3DPRIM_LINELIST:
  82       case _3DPRIM_LINESTRIP:
  83       case _3DPRIM_LINELOOP:
  84          return true;
  85       }
  86    }
  87    return false;
  88 }
  89
  90 static void
  91 upload_clip_state(struct brw_context *brw)
  92 {
  93    struct gl_context *ctx = &brw->ctx;
  94    /* BRW_NEW_META_IN_PROGRESS */
  95    uint32_t dw1 = brw->meta_in_progress ? 0 : GEN6_CLIP_STATISTICS_ENABLE;
  96    uint32_t dw2 = 0;
  97
  98    /* _NEW_BUFFERS */
  99    struct gl_framebuffer *fb = ctx->DrawBuffer;
 100
 101    /* BRW_NEW_FS_PROG_DATA */
 102    if (brw_wm_prog_data(brw->wm.base.prog_data)->barycentric_interp_modes &
 103        BRW_BARYCENTRIC_NONPERSPECTIVE_BITS) {
 104       dw2 |= GEN6_CLIP_NON_PERSPECTIVE_BARYCENTRIC_ENABLE;
 105    }
 106
 107    /* BRW_NEW_VS_PROG_DATA */
 108    dw1 |= brw_vue_prog_data(brw->vs.base.prog_data)->cull_distance_mask;
 109
 110    if (brw->gen >= 7)
 111       dw1 |= GEN7_CLIP_EARLY_CULL;
 112
 113    if (brw->gen == 7) {
 114       /* _NEW_POLYGON */
 115       if (ctx->Polygon._FrontBit == _mesa_is_user_fbo(fb))
 116          dw1 |= GEN7_CLIP_WINDING_CCW;
 117
 118       if (ctx->Polygon.CullFlag) {
 119          switch (ctx->Polygon.CullFaceMode) {
 120          case GL_FRONT:
 121             dw1 |= GEN7_CLIP_CULLMODE_FRONT;
 122             break;
 123          case GL_BACK:
 124             dw1 |= GEN7_CLIP_CULLMODE_BACK;
 125             break;
 126          case GL_FRONT_AND_BACK:
 127             dw1 |= GEN7_CLIP_CULLMODE_BOTH;
 128             break;
 129          default:
 130             unreachable("Should not get here: invalid CullFlag");
 131          }
 132       } else {
 133          dw1 |= GEN7_CLIP_CULLMODE_NONE;
 134       }
 135    }
 136
 137    if (brw->gen < 8 && !ctx->Transform.DepthClamp)
 138       dw2 |= GEN6_CLIP_Z_TEST;
 139
 140    /* _NEW_LIGHT */
 141    if (ctx->Light.ProvokingVertex == GL_FIRST_VERTEX_CONVENTION) {
 142       dw2 |=
 143          (0 << GEN6_CLIP_TRI_PROVOKE_SHIFT) |
 144          (1 << GEN6_CLIP_TRIFAN_PROVOKE_SHIFT) |
 145          (0 << GEN6_CLIP_LINE_PROVOKE_SHIFT);
 146    } else {
 147       dw2 |=
 148          (2 << GEN6_CLIP_TRI_PROVOKE_SHIFT) |
 149          (2 << GEN6_CLIP_TRIFAN_PROVOKE_SHIFT) |
 150          (1 << GEN6_CLIP_LINE_PROVOKE_SHIFT);
 151    }
 152
 153    /* _NEW_TRANSFORM */
 154    dw2 |= (ctx->Transform.ClipPlanesEnabled <<
 155            GEN6_USER_CLIP_CLIP_DISTANCES_SHIFT);
 156
 157    /* Have the hardware use the user clip distance clip test enable bitmask
 158     * specified here in 3DSTATE_CLIP rather than the one in 3DSTATE_VS/DS/GS.
 159     * We already listen to _NEW_TRANSFORM here, but the other atoms don't
 160     * need to other than this.
 161     */
 162    if (brw->gen >= 8)
 163       dw1 |= GEN8_CLIP_FORCE_USER_CLIP_DISTANCE_BITMASK;
 164
 165    if (ctx->Transform.ClipDepthMode == GL_ZERO_TO_ONE)
 166       dw2 |= GEN6_CLIP_API_D3D;
 167    else
 168       dw2 |= GEN6_CLIP_API_OGL;
 169
 170    dw2 |= GEN6_CLIP_GB_TEST;
 171
 172    /* BRW_NEW_VIEWPORT_COUNT */
 173    const unsigned viewport_count = brw->clip.viewport_count;
 174
 175    /* We need to disable guardband clipping if the guardband (which we always
 176     * program to the maximum screen-space bounding box of 8K x 8K) will be
 177     * smaller than the viewport.
 178     *
 179     * Closely examining the clip determination formulas in the documentation
 180     * reveals that objects will be discarded entirely if they're outside the
 181     * (small) guardband, even if they're within the (large) viewport:
 182     *
 183     *     TR = TR_GB || TR_VPXY || TR_VPZ || TR_UC || TR_NEGW
 184     *     TA   = !TR && TA_GB && TA_VPZ && TA_NEGW
 185     *     MC = !(TA || TR)
 186     *
 187     * (TA is "Trivial Accept", TR is "Trivial Reject", MC is "Must Clip".)
 188     *
 189     * Disabling guardband clipping removes the TR_GB condition, which means
 190     * they'll be considered MC ("Must Clip") unless they're rejected for
 191     * some other reason.
 192     *
 193     * Note that there is no TA_VPXY condition.  If there were, objects entirely
 194     * inside a 16384x16384 viewport would be trivially accepted, breaking the
 195     * "objects must have a screenspace bounding box not exceeding 8K in the X
 196     * or Y direction" restriction.  Instead, they're clipped.
 197     */
 198    for (unsigned i = 0; i < viewport_count; i++) {
 199       if (ctx->ViewportArray[i].Width > 8192 ||
 200           ctx->ViewportArray[i].Height > 8192) {
 201          dw2 &= ~GEN6_CLIP_GB_TEST;
 202          break;
 203       }
 204    }
 205
 206    /* If the viewport dimensions are smaller than the drawable dimensions,
 207     * we have to disable guardband clipping prior to Gen8.  We always program
 208     * the guardband to a fixed size, which is almost always larger than the
 209     * viewport.  Any geometry which intersects the viewport but lies within
 210     * the guardband would bypass the 3D clipping stage, so it wouldn't be
 211     * clipped to the viewport.  Rendering would happen beyond the viewport,
 212     * but still inside the drawable.
 213     *
 214     * Gen8+ introduces a viewport extents test which restricts rendering to
 215     * the viewport, so we can ignore this restriction.
 216     */
 217    if (brw->gen < 8) {
 218       const float fb_width = (float)_mesa_geometric_width(fb);
 219       const float fb_height = (float)_mesa_geometric_height(fb);
 220
 221       for (unsigned i = 0; i < viewport_count; i++) {
 222          if (ctx->ViewportArray[i].X != 0 ||
 223              ctx->ViewportArray[i].Y != 0 ||
 224              ctx->ViewportArray[i].Width != fb_width ||
 225              ctx->ViewportArray[i].Height != fb_height) {
 226             dw2 &= ~GEN6_CLIP_GB_TEST;
 227             break;
 228          }
 229       }
 230    }
 231
 232    /* BRW_NEW_RASTERIZER_DISCARD */
 233    if (ctx->RasterDiscard) {
 234       dw2 |= GEN6_CLIP_MODE_REJECT_ALL;
 235       if (brw->gen == 6) {
 236          perf_debug("Rasterizer discard is currently implemented via the "
 237                     "clipper; having the GS not write primitives would "
 238                     "likely be faster.\n");
 239       }
 240    }
 241
 242    uint32_t enable;
 243    if (brw->primitive == _3DPRIM_RECTLIST)
 244       enable = 0;
 245    else
 246       enable = GEN6_CLIP_ENABLE;
 247
 248    /* _NEW_POLYGON,
 249     * BRW_NEW_GEOMETRY_PROGRAM | BRW_NEW_TES_PROG_DATA | BRW_NEW_PRIMITIVE
 250     */
 251    if (!brw_is_drawing_points(brw) && !brw_is_drawing_lines(brw))
 252       dw2 |= GEN6_CLIP_XY_TEST;
 253
 254    BEGIN_BATCH(4);
 255    OUT_BATCH(_3DSTATE_CLIP << 16 | (4 - 2));
 256    OUT_BATCH(dw1);
 257    OUT_BATCH(enable |
 258              GEN6_CLIP_MODE_NORMAL |
 259              dw2);
 260    OUT_BATCH(U_FIXED(0.125, 3) << GEN6_CLIP_MIN_POINT_WIDTH_SHIFT |
 261              U_FIXED(255.875, 3) << GEN6_CLIP_MAX_POINT_WIDTH_SHIFT |
 262              (_mesa_geometric_layers(fb) > 0 ? 0 : GEN6_CLIP_FORCE_ZERO_RTAINDEX) |
 263              ((viewport_count - 1) & GEN6_CLIP_MAX_VP_INDEX_MASK));
 264    ADVANCE_BATCH();
 265 }
 266
 267 const struct brw_tracked_state gen6_clip_state = {
 268    .dirty = {
 269       .mesa  = _NEW_BUFFERS |
 270                _NEW_LIGHT |
 271                _NEW_POLYGON |
 272                _NEW_TRANSFORM,
 273       .brw   = BRW_NEW_BLORP |
 274                BRW_NEW_CONTEXT |
 275                BRW_NEW_FS_PROG_DATA |
 276                BRW_NEW_GS_PROG_DATA |
 277                BRW_NEW_VS_PROG_DATA |
 278                BRW_NEW_META_IN_PROGRESS |
 279                BRW_NEW_PRIMITIVE |
 280                BRW_NEW_RASTERIZER_DISCARD |
 281                BRW_NEW_TES_PROG_DATA |
 282                BRW_NEW_VIEWPORT_COUNT,
 283    },
 284    .emit = upload_clip_state,
 285 };