src/mesa/drivers/dri/i965/gen6_viewport_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 "intel_batchbuffer.h"
  32 #include "main/fbobject.h"
  33 #include "main/framebuffer.h"
  34 #include "main/viewport.h"
  35
  36 void
  37 brw_calculate_guardband_size(const struct gen_device_info *devinfo,
  38                              uint32_t fb_width, uint32_t fb_height,
  39                              float m00, float m11, float m30, float m31,
  40                              float *xmin, float *xmax,
  41                              float *ymin, float *ymax)
  42 {
  43    /* According to the "Vertex X,Y Clamping and Quantization" section of the
  44     * Strips and Fans documentation:
  45     *
  46     * "The vertex X and Y screen-space coordinates are also /clamped/ to the
  47     *  fixed-point "guardband" range supported by the rasterization hardware"
  48     *
  49     * and
  50     *
  51     * "In almost all circumstances, if an object’s vertices are actually
  52     *  modified by this clamping (i.e., had X or Y coordinates outside of
  53     *  the guardband extent the rendered object will not match the intended
  54     *  result.  Therefore software should take steps to ensure that this does
  55     *  not happen - e.g., by clipping objects such that they do not exceed
  56     *  these limits after the Drawing Rectangle is applied."
  57     *
  58     * I believe the fundamental restriction is that the rasterizer (in
  59     * the SF/WM stages) have a limit on the number of pixels that can be
  60     * rasterized.  We need to ensure any coordinates beyond the rasterizer
  61     * limit are handled by the clipper.  So effectively that limit becomes
  62     * the clipper's guardband size.
  63     *
  64     * It goes on to say:
  65     *
  66     * "In addition, in order to be correctly rendered, objects must have a
  67     *  screenspace bounding box not exceeding 8K in the X or Y direction.
  68     *  This additional restriction must also be comprehended by software,
  69     *  i.e., enforced by use of clipping."
  70     *
  71     * This makes no sense.  Gen7+ hardware supports 16K render targets,
  72     * and you definitely need to be able to draw polygons that fill the
  73     * surface.  Our assumption is that the rasterizer was limited to 8K
  74     * on Sandybridge, which only supports 8K surfaces, and it was actually
  75     * increased to 16K on Ivybridge and later.
  76     *
  77     * So, limit the guardband to 16K on Gen7+ and 8K on Sandybridge.
  78     */
  79    const float gb_size = devinfo->gen >= 7 ? 16384.0f : 8192.0f;
  80
  81    if (m00 != 0 && m11 != 0) {
  82       /* First, we compute the screen-space render area */
  83       const float ss_ra_xmin = MIN3(        0, m30 + m00, m30 - m00);
  84       const float ss_ra_xmax = MAX3( fb_width, m30 + m00, m30 - m00);
  85       const float ss_ra_ymin = MIN3(        0, m31 + m11, m31 - m11);
  86       const float ss_ra_ymax = MAX3(fb_height, m31 + m11, m31 - m11);
  87
  88       /* We want the guardband to be centered on that */
  89       const float ss_gb_xmin = (ss_ra_xmin + ss_ra_xmax) / 2 - gb_size;
  90       const float ss_gb_xmax = (ss_ra_xmin + ss_ra_xmax) / 2 + gb_size;
  91       const float ss_gb_ymin = (ss_ra_ymin + ss_ra_ymax) / 2 - gb_size;
  92       const float ss_gb_ymax = (ss_ra_ymin + ss_ra_ymax) / 2 + gb_size;
  93
  94       /* Now we need it in native device coordinates */
  95       const float ndc_gb_xmin = (ss_gb_xmin - m30) / m00;
  96       const float ndc_gb_xmax = (ss_gb_xmax - m30) / m00;
  97       const float ndc_gb_ymin = (ss_gb_ymin - m31) / m11;
  98       const float ndc_gb_ymax = (ss_gb_ymax - m31) / m11;
  99
 100       /* Thanks to Y-flipping and ORIGIN_UPPER_LEFT, the Y coordinates may be
 101        * flipped upside-down.  X should be fine though.
 102        */
 103       assert(ndc_gb_xmin <= ndc_gb_xmax);
 104       *xmin = ndc_gb_xmin;
 105       *xmax = ndc_gb_xmax;
 106       *ymin = MIN2(ndc_gb_ymin, ndc_gb_ymax);
 107       *ymax = MAX2(ndc_gb_ymin, ndc_gb_ymax);
 108    } else {
 109       /* The viewport scales to 0, so nothing will be rendered. */
 110       *xmin = 0.0f;
 111       *xmax = 0.0f;
 112       *ymin = 0.0f;
 113       *ymax = 0.0f;
 114    }
 115 }
 116
 117 static void
 118 gen6_upload_sf_and_clip_viewports(struct brw_context *brw)
 119 {
 120    struct gl_context *ctx = &brw->ctx;
 121    const struct gen_device_info *devinfo = &brw->screen->devinfo;
 122    struct gen6_sf_viewport *sfv;
 123    struct brw_clipper_viewport *clv;
 124    GLfloat y_scale, y_bias;
 125
 126    /* BRW_NEW_VIEWPORT_COUNT */
 127    const unsigned viewport_count = brw->clip.viewport_count;
 128
 129    /* _NEW_BUFFERS */
 130    struct gl_framebuffer *fb = ctx->DrawBuffer;
 131    const bool render_to_fbo = _mesa_is_user_fbo(fb);
 132    const uint32_t fb_width = _mesa_geometric_width(ctx->DrawBuffer);
 133    const uint32_t fb_height = _mesa_geometric_height(ctx->DrawBuffer);
 134
 135    sfv = brw_state_batch(brw, sizeof(*sfv) * viewport_count,
 136                          32, &brw->sf.vp_offset);
 137    memset(sfv, 0, sizeof(*sfv) * viewport_count);
 138
 139    clv = brw_state_batch(brw, sizeof(*clv) * viewport_count,
 140                          32, &brw->clip.vp_offset);
 141
 142    if (render_to_fbo) {
 143       y_scale = 1.0;
 144       y_bias = 0.0;
 145    } else {
 146       y_scale = -1.0;
 147       y_bias = (float)fb_height;
 148    }
 149
 150    for (unsigned i = 0; i < viewport_count; i++) {
 151       float scale[3], translate[3];
 152
 153       /* _NEW_VIEWPORT */
 154       _mesa_get_viewport_xform(ctx, i, scale, translate);
 155       sfv[i].m00 = scale[0];
 156       sfv[i].m11 = scale[1] * y_scale;
 157       sfv[i].m22 = scale[2];
 158       sfv[i].m30 = translate[0];
 159       sfv[i].m31 = translate[1] * y_scale + y_bias;
 160       sfv[i].m32 = translate[2];
 161
 162       brw_calculate_guardband_size(devinfo, fb_width, fb_height,
 163                                    sfv[i].m00, sfv[i].m11,
 164                                    sfv[i].m30, sfv[i].m31,
 165                                    &clv[i].xmin, &clv[i].xmax,
 166                                    &clv[i].ymin, &clv[i].ymax);
 167    }
 168
 169    brw->ctx.NewDriverState |= BRW_NEW_SF_VP | BRW_NEW_CLIP_VP;
 170 }
 171
 172 const struct brw_tracked_state gen6_sf_and_clip_viewports = {
 173    .dirty = {
 174       .mesa = _NEW_BUFFERS |
 175               _NEW_VIEWPORT,
 176       .brw = BRW_NEW_BATCH |
 177              BRW_NEW_BLORP |
 178              BRW_NEW_VIEWPORT_COUNT,
 179    },
 180    .emit = gen6_upload_sf_and_clip_viewports,
 181 };
 182
 183 static void upload_viewport_state_pointers(struct brw_context *brw)
 184 {
 185    BEGIN_BATCH(4);
 186    OUT_BATCH(_3DSTATE_VIEWPORT_STATE_POINTERS << 16 | (4 - 2) |
 187              GEN6_CC_VIEWPORT_MODIFY |
 188              GEN6_SF_VIEWPORT_MODIFY |
 189              GEN6_CLIP_VIEWPORT_MODIFY);
 190    OUT_BATCH(brw->clip.vp_offset);
 191    OUT_BATCH(brw->sf.vp_offset);
 192    OUT_BATCH(brw->cc.vp_offset);
 193    ADVANCE_BATCH();
 194 }
 195
 196 const struct brw_tracked_state gen6_viewport_state = {
 197    .dirty = {
 198       .mesa = 0,
 199       .brw = BRW_NEW_BATCH |
 200              BRW_NEW_BLORP |
 201              BRW_NEW_CC_VP |
 202              BRW_NEW_CLIP_VP |
 203              BRW_NEW_SF_VP |
 204              BRW_NEW_STATE_BASE_ADDRESS,
 205    },
 206    .emit = upload_viewport_state_pointers,
 207 };