src/mesa/drivers/dri/i965/gen8_viewport_state.c

   1 /*
   2  * Copyright © 2011 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
  24 #include "brw_context.h"
  25 #include "brw_state.h"
  26 #include "brw_defines.h"
  27 #include "intel_batchbuffer.h"
  28 #include "main/fbobject.h"
  29 #include "main/framebuffer.h"
  30 #include "main/viewport.h"
  31
  32 static void
  33 gen8_upload_sf_clip_viewport(struct brw_context *brw)
  34 {
  35    struct gl_context *ctx = &brw->ctx;
  36    float y_scale, y_bias;
  37    const float fb_height = (float)_mesa_geometric_height(ctx->DrawBuffer);
  38    const bool render_to_fbo = _mesa_is_user_fbo(ctx->DrawBuffer);
  39
  40    float *vp = brw_state_batch(brw, AUB_TRACE_SF_VP_STATE,
  41                                16 * 4 * ctx->Const.MaxViewports,
  42                                64, &brw->sf.vp_offset);
  43    /* Also assign to clip.vp_offset in case something uses it. */
  44    brw->clip.vp_offset = brw->sf.vp_offset;
  45
  46    /* _NEW_BUFFERS */
  47    if (render_to_fbo) {
  48       y_scale = 1.0;
  49       y_bias = 0;
  50    } else {
  51       y_scale = -1.0;
  52       y_bias = fb_height;
  53    }
  54
  55    for (unsigned i = 0; i < ctx->Const.MaxViewports; i++) {
  56       float scale[3], translate[3];
  57       _mesa_get_viewport_xform(ctx, i, scale, translate);
  58
  59       /* _NEW_VIEWPORT: Viewport Matrix Elements */
  60       vp[0] = scale[0];                        /* m00 */
  61       vp[1] = scale[1] * y_scale;              /* m11 */
  62       vp[2] = scale[2];                        /* m22 */
  63       vp[3] = translate[0];                    /* m30 */
  64       vp[4] = translate[1] * y_scale + y_bias; /* m31 */
  65       vp[5] = translate[2];                    /* m32 */
  66
  67       /* Reserved */
  68       vp[6] = 0;
  69       vp[7] = 0;
  70
  71       /* According to the "Vertex X,Y Clamping and Quantization" section of the
  72        * Strips and Fans documentation, objects must not have a screen-space
  73        * extents of over 8192 pixels, or they may be mis-rasterized.  The
  74        * maximum screen space coordinates of a small object may larger, but we
  75        * have no way to enforce the object size other than through clipping.
  76        *
  77        * The goal is to create the maximum sized guardband (8K x 8K) with the
  78        * viewport rectangle in the center of the guardband. This looks weird
  79        * because the hardware wants coordinates that are scaled to the viewport
  80        * in NDC. In other words, an 8K x 8K viewport would have [-1,1] for X and Y.
  81        * A 4K viewport would be [-2,2], 2K := [-4,4] etc.
  82        *
  83        * --------------------------------
  84        * |Guardband                     |
  85        * |                              |
  86        * |         ------------         |
  87        * |         |viewport  |         |
  88        * |         |          |         |
  89        * |         |          |         |
  90        * |         |__________|         |
  91        * |                              |
  92        * |                              |
  93        * |______________________________|
  94        *
  95        */
  96       const float maximum_guardband_extent = 8192;
  97       float gbx = maximum_guardband_extent / ctx->ViewportArray[i].Width;
  98       float gby = maximum_guardband_extent / ctx->ViewportArray[i].Height;
  99
 100       /* _NEW_VIEWPORT: Guardband Clipping */
 101       vp[8]  = -gbx; /* x-min */
 102       vp[9]  =  gbx; /* x-max */
 103       vp[10] = -gby; /* y-min */
 104       vp[11] =  gby; /* y-max */
 105
 106       /* _NEW_VIEWPORT | _NEW_BUFFERS: Screen Space Viewport
 107        * The hardware will take the intersection of the drawing rectangle,
 108        * scissor rectangle, and the viewport extents. We don't need to be
 109        * smart, and can therefore just program the viewport extents.
 110        */
 111       float viewport_Xmax = ctx->ViewportArray[i].X + ctx->ViewportArray[i].Width;
 112       float viewport_Ymax = ctx->ViewportArray[i].Y + ctx->ViewportArray[i].Height;
 113       if (render_to_fbo) {
 114          vp[12] = ctx->ViewportArray[i].X;
 115          vp[13] = viewport_Xmax - 1;
 116          vp[14] = ctx->ViewportArray[i].Y;
 117          vp[15] = viewport_Ymax - 1;
 118       } else {
 119          vp[12] = ctx->ViewportArray[i].X;
 120          vp[13] = viewport_Xmax - 1;
 121          vp[14] = fb_height - viewport_Ymax;
 122          vp[15] = fb_height - ctx->ViewportArray[i].Y - 1;
 123       }
 124
 125       vp += 16;
 126    }
 127
 128    BEGIN_BATCH(2);
 129    OUT_BATCH(_3DSTATE_VIEWPORT_STATE_POINTERS_SF_CL << 16 | (2 - 2));
 130    OUT_BATCH(brw->sf.vp_offset);
 131    ADVANCE_BATCH();
 132 }
 133
 134 const struct brw_tracked_state gen8_sf_clip_viewport = {
 135    .dirty = {
 136       .mesa = _NEW_BUFFERS |
 137               _NEW_VIEWPORT,
 138       .brw = BRW_NEW_BATCH,
 139    },
 140    .emit = gen8_upload_sf_clip_viewport,
 141 };