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 static void
  37 upload_clip_state(struct brw_context *brw)
  38 {
  39    struct gl_context *ctx = &brw->ctx;
  40    /* BRW_NEW_META_IN_PROGRESS */
  41    uint32_t dw1 = brw->meta_in_progress ? 0 : GEN6_CLIP_STATISTICS_ENABLE;
  42    uint32_t dw2 = 0;
  43
  44    /* _NEW_BUFFERS */
  45    struct gl_framebuffer *fb = ctx->DrawBuffer;
  46
  47    /* BRW_NEW_FS_PROG_DATA */
  48    if (brw->wm.prog_data->barycentric_interp_modes &
  49        BRW_WM_NONPERSPECTIVE_BARYCENTRIC_BITS) {
  50       dw2 |= GEN6_CLIP_NON_PERSPECTIVE_BARYCENTRIC_ENABLE;
  51    }
  52
  53    dw1 |= brw->vs.prog_data->base.cull_distance_mask;
  54
  55    if (brw->gen >= 7)
  56       dw1 |= GEN7_CLIP_EARLY_CULL;
  57
  58    if (brw->gen == 7) {
  59       /* _NEW_POLYGON */
  60       if (ctx->Polygon._FrontBit == _mesa_is_user_fbo(fb))
  61          dw1 |= GEN7_CLIP_WINDING_CCW;
  62
  63       if (ctx->Polygon.CullFlag) {
  64          switch (ctx->Polygon.CullFaceMode) {
  65          case GL_FRONT:
  66             dw1 |= GEN7_CLIP_CULLMODE_FRONT;
  67             break;
  68          case GL_BACK:
  69             dw1 |= GEN7_CLIP_CULLMODE_BACK;
  70             break;
  71          case GL_FRONT_AND_BACK:
  72             dw1 |= GEN7_CLIP_CULLMODE_BOTH;
  73             break;
  74          default:
  75             unreachable("Should not get here: invalid CullFlag");
  76          }
  77       } else {
  78          dw1 |= GEN7_CLIP_CULLMODE_NONE;
  79       }
  80    }
  81
  82    if (brw->gen < 8 && !ctx->Transform.DepthClamp)
  83       dw2 |= GEN6_CLIP_Z_TEST;
  84
  85    /* _NEW_LIGHT */
  86    if (ctx->Light.ProvokingVertex == GL_FIRST_VERTEX_CONVENTION) {
  87       dw2 |=
  88          (0 << GEN6_CLIP_TRI_PROVOKE_SHIFT) |
  89          (1 << GEN6_CLIP_TRIFAN_PROVOKE_SHIFT) |
  90          (0 << GEN6_CLIP_LINE_PROVOKE_SHIFT);
  91    } else {
  92       dw2 |=
  93          (2 << GEN6_CLIP_TRI_PROVOKE_SHIFT) |
  94          (2 << GEN6_CLIP_TRIFAN_PROVOKE_SHIFT) |
  95          (1 << GEN6_CLIP_LINE_PROVOKE_SHIFT);
  96    }
  97
  98    /* _NEW_TRANSFORM */
  99    dw2 |= (ctx->Transform.ClipPlanesEnabled <<
 100            GEN6_USER_CLIP_CLIP_DISTANCES_SHIFT);
 101    if (ctx->Transform.ClipDepthMode == GL_ZERO_TO_ONE)
 102       dw2 |= GEN6_CLIP_API_D3D;
 103    else
 104       dw2 |= GEN6_CLIP_API_OGL;
 105
 106    dw2 |= GEN6_CLIP_GB_TEST;
 107
 108    /* We need to disable guardband clipping if the guardband (which we always
 109     * program to the maximum screen-space bounding box of 8K x 8K) will be
 110     * smaller than the viewport.
 111     *
 112     * Closely examining the clip determination formulas in the documentation
 113     * reveals that objects will be discarded entirely if they're outside the
 114     * (small) guardband, even if they're within the (large) viewport:
 115     *
 116     *     TR = TR_GB || TR_VPXY || TR_VPZ || TR_UC || TR_NEGW
 117     *     TA   = !TR && TA_GB && TA_VPZ && TA_NEGW
 118     *     MC = !(TA || TR)
 119     *
 120     * (TA is "Trivial Accept", TR is "Trivial Reject", MC is "Must Clip".)
 121     *
 122     * Disabling guardband clipping removes the TR_GB condition, which means
 123     * they'll be considered MC ("Must Clip") unless they're rejected for
 124     * some other reason.
 125     *
 126     * Note that there is no TA_VPXY condition.  If there were, objects entirely
 127     * inside a 16384x16384 viewport would be trivially accepted, breaking the
 128     * "objects must have a screenspace bounding box not exceeding 8K in the X
 129     * or Y direction" restriction.  Instead, they're clipped.
 130     */
 131    for (unsigned i = 0; i < ctx->Const.MaxViewports; i++) {
 132       if (ctx->ViewportArray[i].Width > 8192 ||
 133           ctx->ViewportArray[i].Height > 8192) {
 134          dw2 &= ~GEN6_CLIP_GB_TEST;
 135          break;
 136       }
 137    }
 138
 139    /* If the viewport dimensions are smaller than the drawable dimensions,
 140     * we have to disable guardband clipping prior to Gen8.  We always program
 141     * the guardband to a fixed size, which is almost always larger than the
 142     * viewport.  Any geometry which intersects the viewport but lies within
 143     * the guardband would bypass the 3D clipping stage, so it wouldn't be
 144     * clipped to the viewport.  Rendering would happen beyond the viewport,
 145     * but still inside the drawable.
 146     *
 147     * Gen8+ introduces a viewport extents test which restricts rendering to
 148     * the viewport, so we can ignore this restriction.
 149     */
 150    if (brw->gen < 8) {
 151       const float fb_width = (float)_mesa_geometric_width(fb);
 152       const float fb_height = (float)_mesa_geometric_height(fb);
 153
 154       for (unsigned i = 0; i < ctx->Const.MaxViewports; i++) {
 155          if (ctx->ViewportArray[i].X != 0 ||
 156              ctx->ViewportArray[i].Y != 0 ||
 157              ctx->ViewportArray[i].Width != fb_width ||
 158              ctx->ViewportArray[i].Height != fb_height) {
 159             dw2 &= ~GEN6_CLIP_GB_TEST;
 160             break;
 161          }
 162       }
 163    }
 164
 165    /* BRW_NEW_RASTERIZER_DISCARD */
 166    if (ctx->RasterDiscard) {
 167       dw2 |= GEN6_CLIP_MODE_REJECT_ALL;
 168       perf_debug("Rasterizer discard is currently implemented via the clipper; "
 169                  "%s be faster.\n", brw->gen >= 7 ? "using the SOL unit may" :
 170                  "having the GS not write primitives would likely");
 171    }
 172
 173    uint32_t enable;
 174    if (brw->primitive == _3DPRIM_RECTLIST)
 175       enable = 0;
 176    else
 177       enable = GEN6_CLIP_ENABLE;
 178
 179    if (!is_drawing_points(brw) && !is_drawing_lines(brw))
 180       dw2 |= GEN6_CLIP_XY_TEST;
 181
 182    /* BRW_NEW_VUE_MAP_GEOM_OUT */
 183    const int max_vp_index =
 184       (brw->vue_map_geom_out.slots_valid & VARYING_BIT_VIEWPORT) != 0 ?
 185       ctx->Const.MaxViewports : 1;
 186
 187    BEGIN_BATCH(4);
 188    OUT_BATCH(_3DSTATE_CLIP << 16 | (4 - 2));
 189    OUT_BATCH(dw1);
 190    OUT_BATCH(enable |
 191              GEN6_CLIP_MODE_NORMAL |
 192              dw2);
 193    OUT_BATCH(U_FIXED(0.125, 3) << GEN6_CLIP_MIN_POINT_WIDTH_SHIFT |
 194              U_FIXED(255.875, 3) << GEN6_CLIP_MAX_POINT_WIDTH_SHIFT |
 195              (_mesa_geometric_layers(fb) > 0 ? 0 : GEN6_CLIP_FORCE_ZERO_RTAINDEX) |
 196              ((max_vp_index - 1) & GEN6_CLIP_MAX_VP_INDEX_MASK));
 197    ADVANCE_BATCH();
 198 }
 199
 200 const struct brw_tracked_state gen6_clip_state = {
 201    .dirty = {
 202       .mesa  = _NEW_BUFFERS |
 203                _NEW_LIGHT |
 204                _NEW_TRANSFORM,
 205       .brw   = BRW_NEW_BLORP |
 206                BRW_NEW_CONTEXT |
 207                BRW_NEW_FS_PROG_DATA |
 208                BRW_NEW_GEOMETRY_PROGRAM |
 209                BRW_NEW_META_IN_PROGRESS |
 210                BRW_NEW_PRIMITIVE |
 211                BRW_NEW_RASTERIZER_DISCARD |
 212                BRW_NEW_VUE_MAP_GEOM_OUT,
 213    },
 214    .emit = upload_clip_state,
 215 };
 216
 217 const struct brw_tracked_state gen7_clip_state = {
 218    .dirty = {
 219       .mesa  = _NEW_BUFFERS |
 220                _NEW_LIGHT |
 221                _NEW_POLYGON |
 222                _NEW_TRANSFORM,
 223       .brw   = BRW_NEW_BLORP |
 224                BRW_NEW_CONTEXT |
 225                BRW_NEW_FS_PROG_DATA |
 226                BRW_NEW_GEOMETRY_PROGRAM |
 227                BRW_NEW_META_IN_PROGRESS |
 228                BRW_NEW_PRIMITIVE |
 229                BRW_NEW_RASTERIZER_DISCARD |
 230                BRW_NEW_VUE_MAP_GEOM_OUT,
 231    },
 232    .emit = upload_clip_state,
 233 };