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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
brw_calculate_guardband_size(const struct gen_device_info * devinfo,uint32_t fb_width,uint32_t fb_height,float m00,float m11,float m30,float m31,float * xmin,float * xmax,float * ymin,float * ymax)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
gen6_upload_sf_and_clip_viewports(struct brw_context * brw)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, AUB_TRACE_SF_VP_STATE,
136                          sizeof(*sfv) * viewport_count,
137                          32, &brw->sf.vp_offset);
138    memset(sfv, 0, sizeof(*sfv) * viewport_count);
139 
140    clv = brw_state_batch(brw, AUB_TRACE_CLIP_VP_STATE,
141                          sizeof(*clv) * viewport_count,
142                          32, &brw->clip.vp_offset);
143 
144    if (render_to_fbo) {
145       y_scale = 1.0;
146       y_bias = 0.0;
147    } else {
148       y_scale = -1.0;
149       y_bias = (float)fb_height;
150    }
151 
152    for (unsigned i = 0; i < viewport_count; i++) {
153       float scale[3], translate[3];
154 
155       /* _NEW_VIEWPORT */
156       _mesa_get_viewport_xform(ctx, i, scale, translate);
157       sfv[i].m00 = scale[0];
158       sfv[i].m11 = scale[1] * y_scale;
159       sfv[i].m22 = scale[2];
160       sfv[i].m30 = translate[0];
161       sfv[i].m31 = translate[1] * y_scale + y_bias;
162       sfv[i].m32 = translate[2];
163 
164       brw_calculate_guardband_size(devinfo, fb_width, fb_height,
165                                    sfv[i].m00, sfv[i].m11,
166                                    sfv[i].m30, sfv[i].m31,
167                                    &clv[i].xmin, &clv[i].xmax,
168                                    &clv[i].ymin, &clv[i].ymax);
169    }
170 
171    brw->ctx.NewDriverState |= BRW_NEW_SF_VP | BRW_NEW_CLIP_VP;
172 }
173 
174 const struct brw_tracked_state gen6_sf_and_clip_viewports = {
175    .dirty = {
176       .mesa = _NEW_BUFFERS |
177               _NEW_VIEWPORT,
178       .brw = BRW_NEW_BATCH |
179              BRW_NEW_BLORP |
180              BRW_NEW_VIEWPORT_COUNT,
181    },
182    .emit = gen6_upload_sf_and_clip_viewports,
183 };
184 
upload_viewport_state_pointers(struct brw_context * brw)185 static void upload_viewport_state_pointers(struct brw_context *brw)
186 {
187    BEGIN_BATCH(4);
188    OUT_BATCH(_3DSTATE_VIEWPORT_STATE_POINTERS << 16 | (4 - 2) |
189 	     GEN6_CC_VIEWPORT_MODIFY |
190 	     GEN6_SF_VIEWPORT_MODIFY |
191 	     GEN6_CLIP_VIEWPORT_MODIFY);
192    OUT_BATCH(brw->clip.vp_offset);
193    OUT_BATCH(brw->sf.vp_offset);
194    OUT_BATCH(brw->cc.vp_offset);
195    ADVANCE_BATCH();
196 }
197 
198 const struct brw_tracked_state gen6_viewport_state = {
199    .dirty = {
200       .mesa = 0,
201       .brw = BRW_NEW_BATCH |
202              BRW_NEW_BLORP |
203              BRW_NEW_CC_VP |
204              BRW_NEW_CLIP_VP |
205              BRW_NEW_SF_VP |
206              BRW_NEW_STATE_BASE_ADDRESS,
207    },
208    .emit = upload_viewport_state_pointers,
209 };
210