/*
 * Copyright © 2011 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.
 */

#include "brw_context.h"
#include "brw_state.h"
#include "brw_defines.h"
#include "intel_batchbuffer.h"
#include "main/fbobject.h"
#include "main/framebuffer.h"
#include "main/viewport.h"

static void
gen7_upload_sf_clip_viewport(struct brw_context *brw)
{
   struct gl_context *ctx = &brw->ctx;
   GLfloat y_scale, y_bias;
   const bool render_to_fbo = _mesa_is_user_fbo(ctx->DrawBuffer);
   struct gen7_sf_clip_viewport *vp;

   /* BRW_NEW_VIEWPORT_COUNT */
   const unsigned viewport_count = brw->clip.viewport_count;

   vp = brw_state_batch(brw, AUB_TRACE_SF_VP_STATE,
                        sizeof(*vp) * viewport_count, 64,
                        &brw->sf.vp_offset);
   /* Also assign to clip.vp_offset in case something uses it. */
   brw->clip.vp_offset = brw->sf.vp_offset;

   /* _NEW_BUFFERS */
   if (render_to_fbo) {
      y_scale = 1.0;
      y_bias = 0.0;
   } else {
      y_scale = -1.0;
      y_bias = (float)_mesa_geometric_height(ctx->DrawBuffer);
   }

   for (unsigned i = 0; i < viewport_count; i++) {
      float scale[3], translate[3];
      _mesa_get_viewport_xform(ctx, i, scale, translate);

      /* According to the "Vertex X,Y Clamping and Quantization" section of
       * the Strips and Fans documentation, objects must not have a
       * screen-space extents of over 8192 pixels, or they may be
       * mis-rasterized.  The maximum screen space coordinates of a small
       * object may larger, but we have no way to enforce the object size
       * other than through clipping.
       *
       * If you're surprised that we set clip to -gbx to +gbx and it seems
       * like we'll end up with 16384 wide, note that for a 8192-wide render
       * target, we'll end up with a normal (-1, 1) clip volume that just
       * covers the drawable.
       */
      const float maximum_guardband_extent = 8192;
      const float gbx = maximum_guardband_extent / ctx->ViewportArray[i].Width;
      const float gby = maximum_guardband_extent / ctx->ViewportArray[i].Height;

      vp[i].guardband.xmin = -gbx;
      vp[i].guardband.xmax = gbx;
      vp[i].guardband.ymin = -gby;
      vp[i].guardband.ymax = gby;

      /* _NEW_VIEWPORT */
      vp[i].viewport.m00 = scale[0];
      vp[i].viewport.m11 = scale[1] * y_scale;
      vp[i].viewport.m22 = scale[2];
      vp[i].viewport.m30 = translate[0];
      vp[i].viewport.m31 = translate[1] * y_scale + y_bias;
      vp[i].viewport.m32 = translate[2];
   }

   BEGIN_BATCH(2);
   OUT_BATCH(_3DSTATE_VIEWPORT_STATE_POINTERS_SF_CL << 16 | (2 - 2));
   OUT_BATCH(brw->sf.vp_offset);
   ADVANCE_BATCH();
}

const struct brw_tracked_state gen7_sf_clip_viewport = {
   .dirty = {
      .mesa = _NEW_BUFFERS |
              _NEW_VIEWPORT,
      .brw = BRW_NEW_BATCH |
             BRW_NEW_BLORP |
             BRW_NEW_VIEWPORT_COUNT,
   },
   .emit = gen7_upload_sf_clip_viewport,
};
