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/*

 * Copyright © 2009 Intel Corporation

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice (including the next

 * paragraph) shall be included in all copies or substantial portions of the

 * Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 *

 * Authors:

 *    Eric Anholt 

 *

 */

#include "brw_context.h"

#include "brw_state.h"

#include "brw_defines.h"

#include "brw_util.h"

#include "intel_batchbuffer.h"

#include "main/fbobject.h"

static void

upload_clip_state(struct brw_context *brw)

{

   struct gl_context *ctx = &brw->ctx;

   /* BRW_NEW_META_IN_PROGRESS */

   uint32_t dw1 = brw->meta_in_progress ? 0 : GEN6_CLIP_STATISTICS_ENABLE;

   uint32_t dw2 = 0;

   /* _NEW_BUFFERS */

   struct gl_framebuffer *fb = ctx->DrawBuffer;

   /* BRW_NEW_FS_PROG_DATA */

   if (brw->wm.prog_data->barycentric_interp_modes &

       BRW_WM_NONPERSPECTIVE_BARYCENTRIC_BITS) {

      dw2 |= GEN6_CLIP_NON_PERSPECTIVE_BARYCENTRIC_ENABLE;

   }

   if (brw->gen >= 7)

      dw1 |= GEN7_CLIP_EARLY_CULL;

   if (brw->gen == 7) {

      /* _NEW_POLYGON */

      if (ctx->Polygon._FrontBit == _mesa_is_user_fbo(fb))

         dw1 |= GEN7_CLIP_WINDING_CCW;

      if (ctx->Polygon.CullFlag) {

         switch (ctx->Polygon.CullFaceMode) {

         case GL_FRONT:

            dw1 |= GEN7_CLIP_CULLMODE_FRONT;

            break;

         case GL_BACK:

            dw1 |= GEN7_CLIP_CULLMODE_BACK;

            break;

         case GL_FRONT_AND_BACK:

            dw1 |= GEN7_CLIP_CULLMODE_BOTH;

            break;

         default:

            unreachable("Should not get here: invalid CullFlag");

         }

      } else {

         dw1 |= GEN7_CLIP_CULLMODE_NONE;

      }

   }

   if (brw->gen < 8 && !ctx->Transform.DepthClamp)

      dw2 |= GEN6_CLIP_Z_TEST;

   /* _NEW_LIGHT */

   if (ctx->Light.ProvokingVertex == GL_FIRST_VERTEX_CONVENTION) {

      dw2 |=

	 (0 << GEN6_CLIP_TRI_PROVOKE_SHIFT) |

	 (1 << GEN6_CLIP_TRIFAN_PROVOKE_SHIFT) |

	 (0 << GEN6_CLIP_LINE_PROVOKE_SHIFT);

   } else {

      dw2 |=

	 (2 << GEN6_CLIP_TRI_PROVOKE_SHIFT) |

	 (2 << GEN6_CLIP_TRIFAN_PROVOKE_SHIFT) |

	 (1 << GEN6_CLIP_LINE_PROVOKE_SHIFT);

   }

   /* _NEW_TRANSFORM */

   dw2 |= (ctx->Transform.ClipPlanesEnabled <<

           GEN6_USER_CLIP_CLIP_DISTANCES_SHIFT);

   if (ctx->Transform.ClipDepthMode == GL_ZERO_TO_ONE)

      dw2 |= GEN6_CLIP_API_D3D;

   else

      dw2 |= GEN6_CLIP_API_OGL;

   dw2 |= GEN6_CLIP_GB_TEST;

   /* We need to disable guardband clipping if the guardband (which we always

    * program to the maximum screen-space bounding box of 8K x 8K) will be

    * smaller than the viewport.

    *

    * Closely examining the clip determination formulas in the documentation

    * reveals that objects will be discarded entirely if they're outside the

    * (small) guardband, even if they're within the (large) viewport:

    *

    *     TR = TR_GB || TR_VPXY || TR_VPZ || TR_UC || TR_NEGW

    *     TA   = !TR && TA_GB && TA_VPZ && TA_NEGW

    *     MC = !(TA || TR)

    *

    * (TA is "Trivial Accept", TR is "Trivial Reject", MC is "Must Clip".)

    *

    * Disabling guardband clipping removes the TR_GB condition, which means

    * they'll be considered MC ("Must Clip") unless they're rejected for

    * some other reason.

    *

    * Note that there is no TA_VPXY condition.  If there were, objects entirely

    * inside a 16384x16384 viewport would be trivially accepted, breaking the

    * "objects must have a screenspace bounding box not exceeding 8K in the X

    * or Y direction" restriction.  Instead, they're clipped.

    */

   for (unsigned i = 0; i < ctx->Const.MaxViewports; i++) {

      if (ctx->ViewportArray[i].Width > 8192 ||

          ctx->ViewportArray[i].Height > 8192) {

         dw2 &= ~GEN6_CLIP_GB_TEST;

         break;

      }

   }

   /* If the viewport dimensions are smaller than the drawable dimensions,

    * we have to disable guardband clipping prior to Gen8.  We always program

    * the guardband to a fixed size, which is almost always larger than the

    * viewport.  Any geometry which intersects the viewport but lies within

    * the guardband would bypass the 3D clipping stage, so it wouldn't be

    * clipped to the viewport.  Rendering would happen beyond the viewport,

    * but still inside the drawable.

    *

    * Gen8+ introduces a viewport extents test which restricts rendering to

    * the viewport, so we can ignore this restriction.

    */

   if (brw->gen < 8) {

      for (unsigned i = 0; i < ctx->Const.MaxViewports; i++) {

         if (ctx->ViewportArray[i].X != 0 ||

             ctx->ViewportArray[i].Y != 0 ||

             ctx->ViewportArray[i].Width != (float) fb->Width ||

             ctx->ViewportArray[i].Height != (float) fb->Height) {

            dw2 &= ~GEN6_CLIP_GB_TEST;

            break;

         }

      }

   }

   /* BRW_NEW_RASTERIZER_DISCARD */

   if (ctx->RasterDiscard) {

      dw2 |= GEN6_CLIP_MODE_REJECT_ALL;

      perf_debug("Rasterizer discard is currently implemented via the clipper; "

                 "%s be faster.\n", brw->gen >= 7 ? "using the SOL unit may" :

                 "having the GS not write primitives would likely");

   }

   uint32_t enable;

   if (brw->primitive == _3DPRIM_RECTLIST)

      enable = 0;

   else

      enable = GEN6_CLIP_ENABLE;

   BEGIN_BATCH(4);

   OUT_BATCH(_3DSTATE_CLIP << 16 | (4 - 2));

   OUT_BATCH(dw1);

   OUT_BATCH(enable |

	     GEN6_CLIP_MODE_NORMAL |

	     GEN6_CLIP_XY_TEST |

	     dw2);

   OUT_BATCH(U_FIXED(0.125, 3) << GEN6_CLIP_MIN_POINT_WIDTH_SHIFT |

             U_FIXED(255.875, 3) << GEN6_CLIP_MAX_POINT_WIDTH_SHIFT |

             (fb->MaxNumLayers > 0 ? 0 : GEN6_CLIP_FORCE_ZERO_RTAINDEX) |

             ((ctx->Const.MaxViewports - 1) & GEN6_CLIP_MAX_VP_INDEX_MASK));

   ADVANCE_BATCH();

}

const struct brw_tracked_state gen6_clip_state = {

   .dirty = {

      .mesa  = _NEW_BUFFERS |

               _NEW_LIGHT |

               _NEW_TRANSFORM,

      .brw   = BRW_NEW_CONTEXT |

               BRW_NEW_FS_PROG_DATA |

               BRW_NEW_META_IN_PROGRESS |

               BRW_NEW_RASTERIZER_DISCARD,

   },

   .emit = upload_clip_state,

};

const struct brw_tracked_state gen7_clip_state = {

   .dirty = {

      .mesa  = _NEW_BUFFERS |

               _NEW_LIGHT |

               _NEW_POLYGON |

               _NEW_TRANSFORM,

      .brw   = BRW_NEW_CONTEXT |

               BRW_NEW_FS_PROG_DATA |

               BRW_NEW_META_IN_PROGRESS |

               BRW_NEW_RASTERIZER_DISCARD,

   },

   .emit = upload_clip_state,

};