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1 // Copyright 2013 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "cc/quads/draw_polygon.h" | |
6 | |
7 #include <vector> | |
8 | |
9 #include "cc/output/bsp_compare_result.h" | |
10 | |
11 namespace { | |
12 // This allows for some imperfection in the normal comparison when checking if | |
13 // two pieces of geometry are coplanar. | |
14 const float coplanar_dot_epsilon = 0.99f; | |
15 } // namespace | |
16 | |
17 namespace cc { | |
18 | |
19 DrawPolygon::DrawPolygon() { | |
20 } | |
21 | |
22 DrawPolygon::DrawPolygon(DrawQuad* original, | |
23 gfx::Point3F* in_points, | |
24 int num_vertices_in_polygon, | |
25 int draw_order_index, | |
26 bool polygon_is_original) | |
27 : order_index(draw_order_index), | |
28 // offset(0), | |
29 is_original(polygon_is_original), | |
30 original_ref(original) { | |
31 for (int i = 0; i < num_vertices_in_polygon; i++) { | |
32 points.push_back(in_points[i]); | |
33 } | |
34 | |
35 if (num_vertices_in_polygon > 2) { | |
36 gfx::Vector3dF c12 = in_points[1] - in_points[0]; | |
37 gfx::Vector3dF c13 = in_points[2] - in_points[0]; | |
38 normal = gfx::CrossProduct(c12, c13); | |
39 normal.Scale(1.0f / normal.Length()); | |
40 } | |
41 area = Area(); | |
Ian Vollick
2014/07/16 20:54:33
Since area is computed in the ctor and is immutabl
troyhildebrandt
2014/07/18 21:48:26
Done.
| |
42 } | |
43 | |
44 DrawPolygon::DrawPolygon(const DrawPolygon& other) { | |
45 CopyFrom(other); | |
46 } | |
47 | |
48 DrawPolygon::~DrawPolygon() { | |
49 } | |
50 | |
51 DrawPolygon& DrawPolygon::operator=(const DrawPolygon& rhs) { | |
52 CopyFrom(rhs); | |
53 return *this; | |
54 } | |
55 | |
56 void DrawPolygon::CopyFrom(const DrawPolygon& other) { | |
57 order_index = other.order_index; | |
58 is_original = other.is_original; | |
59 original_ref = other.original_ref; | |
60 points.reserve(other.points.size()); | |
61 points = other.points; | |
62 normal.set_x(other.normal.x()); | |
63 normal.set_y(other.normal.y()); | |
64 normal.set_z(other.normal.z()); | |
65 area = other.area; | |
66 } | |
67 | |
68 float DrawPolygon::SignedPointDistance(const gfx::Point3F& point) const { | |
69 return gfx::DotProduct(point - points[0], normal); | |
70 } | |
71 | |
72 // Checks whether or not shape a lies on the front or back side of b, or | |
73 // whether they should be considered coplanar. If on the back side, we | |
74 // say ABeforeB because it should be drawn in that order. | |
75 // Assumes that layers are split and there are no intersecting planes. | |
76 BspCompareResult DrawPolygon::SideCompare(const DrawPolygon& a, | |
77 const DrawPolygon& b, | |
78 float z_threshold) { | |
Ian Vollick
2014/07/16 20:54:33
Multiple exit points nested in if/else's in this f
troyhildebrandt
2014/07/18 21:48:27
Done.
| |
79 // Right away let's check if they're coplanar | |
80 double dot = gfx::DotProduct(a.normal, b.normal); | |
81 float sign; | |
82 bool normal_match = false; | |
83 // This check assumes that the normals are normalized. | |
84 if (std::abs(dot) >= coplanar_dot_epsilon) { | |
85 normal_match = true; | |
86 // The normals are matching enough that we only have to test one point. | |
87 sign = gfx::DotProduct(a.points[0] - b.points[0], b.normal); | |
88 // Is it on either side of the splitter? | |
89 if (sign < -z_threshold) { | |
90 return BSP_BACK; | |
91 } else if (sign > z_threshold) { | |
92 return BSP_FRONT; | |
93 } else { | |
94 // No it wasn't, so the sign of the dot product of the normals | |
95 // along with document order determines which side it goes on. | |
96 if (dot >= 0.0f) { | |
97 if (a.order_index < b.order_index) | |
98 return BSP_COPLANAR_FRONT; | |
99 else | |
100 return BSP_COPLANAR_BACK; | |
101 } else { | |
102 if (a.order_index < b.order_index) | |
103 return BSP_COPLANAR_BACK; | |
104 else | |
105 return BSP_COPLANAR_FRONT; | |
106 } | |
107 } | |
108 } | |
109 | |
110 unsigned int pos_count = 0; | |
111 unsigned int neg_count = 0; | |
112 for (unsigned int i = 0; i < a.points.size(); i++) { | |
113 if (!normal_match || (normal_match && i > 0)) | |
114 sign = gfx::DotProduct(a.points[i] - b.points[0], b.normal); | |
115 if (sign < -z_threshold) | |
116 ++neg_count; | |
117 else if (sign > z_threshold) | |
118 ++pos_count; | |
119 if (pos_count && neg_count) | |
120 return BSP_SPLIT; | |
121 } | |
122 | |
123 if (pos_count) | |
124 return BSP_FRONT; | |
125 return BSP_BACK; | |
126 } | |
127 | |
128 static bool LineIntersectPlane(const gfx::Point3F& line_start, | |
129 const gfx::Point3F& line_end, | |
130 const gfx::Point3F& plane_origin, | |
131 const gfx::Vector3dF& plane_normal, | |
132 gfx::Point3F* intersection, | |
133 float distance_threshold) { | |
134 gfx::Vector3dF vec1 = plane_origin - line_start; | |
135 gfx::Vector3dF vec2 = plane_origin - line_end; | |
136 | |
137 double start_distance = gfx::DotProduct(vec1, plane_normal); | |
138 double end_distance = gfx::DotProduct(vec2, plane_normal); | |
139 | |
140 // The case where one vertex lies on the thick-plane and the other | |
141 // is outside of it. | |
142 if (std::abs(start_distance) < distance_threshold && | |
143 std::abs(end_distance) > distance_threshold) { | |
144 intersection->SetPoint(line_start.x(), line_start.y(), line_start.z()); | |
145 return true; | |
146 } | |
147 | |
148 // This is the case where we clearly cross the thick-plane. | |
149 if ((start_distance > distance_threshold && | |
150 end_distance < -distance_threshold) || | |
151 (start_distance < -distance_threshold && | |
152 end_distance > distance_threshold)) { | |
153 gfx::Vector3dF v = line_end - line_start; | |
154 | |
155 v.Scale(1.f / v.Length()); | |
156 double projected_length = gfx::DotProduct(v, plane_normal); | |
157 if (!projected_length) | |
158 return false; | |
159 | |
160 double scale = start_distance / projected_length; | |
161 intersection->SetPoint(line_start.x() + (v.x() * scale), | |
162 line_start.y() + (v.y() * scale), | |
163 line_start.z() + (v.z() * scale)); | |
164 | |
165 return true; | |
166 } | |
167 return false; | |
168 } | |
169 | |
170 bool DrawPolygon::ApplyTransform(const gfx::Transform& transform) { | |
171 bool clipped = false; | |
172 for (unsigned int i = 0; i < points.size(); i++) { | |
173 points[i] = MathUtil::MapPoint(transform, points[i], &clipped); | |
174 } | |
Ian Vollick
2014/07/16 20:54:33
Couldn't this affect area?
troyhildebrandt
2014/07/18 21:48:27
Yea, I'll take a look and see if I can find a bett
| |
175 return !clipped; | |
176 } | |
177 | |
178 float DrawPolygon::Area() const { | |
179 return std::abs(SignedArea()); | |
180 } | |
181 | |
182 float DrawPolygon::SignedArea() const { | |
183 gfx::Vector3dF total; | |
184 for (unsigned int i = 0; i < points.size(); i++) { | |
185 unsigned int j = (i + 1) % points.size(); | |
186 gfx::Vector3dF cross_prod = gfx::CrossProduct( | |
187 gfx::Vector3dF(points[i].x(), points[i].y(), points[i].z()), | |
188 gfx::Vector3dF(points[j].x(), points[j].y(), points[j].z())); | |
189 total = total + cross_prod; | |
190 } | |
191 return 0.5f * std::abs(gfx::DotProduct(total, normal)); | |
192 } | |
193 | |
194 bool DrawPolygon::Split(const DrawPolygon& splitter, | |
195 double plane_threshold, | |
196 scoped_ptr<DrawPolygon>* front, | |
197 scoped_ptr<DrawPolygon>* back) { | |
198 gfx::Point3F intersections[2]; | |
199 std::vector<gfx::Point3F> out_points[2]; | |
200 int vertex_before[2]; | |
201 int points_size = points.size(); | |
202 int current_intersection = 0; | |
203 | |
204 int current_vertex = 0; | |
205 while (current_intersection < 2) { | |
206 if (current_intersection > 0 && | |
207 vertex_before[0] == (current_vertex % points_size)) { | |
208 continue; | |
209 } | |
210 | |
211 if (LineIntersectPlane(points[(current_vertex % points_size)], | |
212 points[(current_vertex + 1) % points_size], | |
213 splitter.points[0], | |
214 splitter.normal, | |
215 &intersections[current_intersection], | |
216 plane_threshold)) { | |
217 vertex_before[current_intersection] = current_vertex % points_size; | |
218 current_intersection++; | |
219 // We found both intersection points so we're done already. | |
220 if (current_intersection == 2) { | |
221 break; | |
222 } | |
223 } | |
224 ++current_vertex; | |
225 // We've gone around one whole time, leave early. | |
226 if (current_vertex > points_size) { | |
227 break; | |
228 } | |
229 } | |
230 if (current_intersection < 2) { | |
231 return false; | |
232 } | |
233 | |
234 // Since we found both the intersection points, we can begin building the | |
235 // vertex set for both our new polygons. | |
236 int start1 = (vertex_before[0] + 1) % points_size; | |
237 int start2 = (vertex_before[1] + 1) % points_size; | |
238 int points_remaining = points_size; | |
239 | |
240 // First polygon. | |
241 out_points[0].push_back(intersections[0]); | |
242 for (int i = start1; i <= vertex_before[1]; i++) { | |
243 out_points[0].push_back(points[i]); | |
244 --points_remaining; | |
245 } | |
246 out_points[0].push_back(intersections[1]); | |
247 | |
248 // Second polygon. | |
249 out_points[1].push_back(intersections[1]); | |
250 int index = start2; | |
251 for (int i = 0; i < points_remaining; i++) { | |
252 out_points[1].push_back(points[index % points_size]); | |
253 ++index; | |
254 } | |
255 out_points[1].push_back(intersections[0]); | |
256 | |
257 // Give both polygons the original splitting polygon's ID, so that they'll | |
258 // still be sorted properly in co-planar instances. | |
259 // Send false as last parameter for is_original because they're split. | |
260 scoped_ptr<DrawPolygon> poly1(new DrawPolygon(original_ref, | |
261 &(out_points[0][0]), | |
262 out_points[0].size(), | |
263 this->order_index, | |
264 false)); | |
265 scoped_ptr<DrawPolygon> poly2(new DrawPolygon(original_ref, | |
266 &(out_points[1][0]), | |
267 out_points[1].size(), | |
268 this->order_index, | |
269 false)); | |
270 | |
271 if (SideCompare(*poly1, splitter, plane_threshold) == BSP_FRONT) { | |
272 *front = poly1.Pass(); | |
273 *back = poly2.Pass(); | |
274 } else { | |
275 *front = poly2.Pass(); | |
276 *back = poly1.Pass(); | |
277 } | |
278 return true; | |
279 } | |
280 | |
281 void DrawPolygon::ToQuads2D(std::vector<gfx::QuadF>* quads) const { | |
282 if (points.size() == 0) | |
283 return; | |
284 | |
285 // op1 = offset plus 1, op2 = offset plus 2. | |
286 gfx::PointF first(points[0].x(), points[0].y()); | |
287 unsigned int offset = 1; | |
288 while (offset < points.size() - 1) { | |
289 unsigned int op1 = offset + 1; | |
290 unsigned int op2 = offset + 2; | |
291 if (op2 >= points.size()) { | |
292 // It's going to be a degenerate triangle. | |
293 op2 = op1; | |
294 } | |
295 quads->push_back( | |
296 gfx::QuadF(first, | |
297 gfx::PointF(points[offset].x(), points[offset].y()), | |
298 gfx::PointF(points[op1].x(), points[op1].y()), | |
299 gfx::PointF(points[op2].x(), points[op2].y()))); | |
300 offset = op2; | |
301 } | |
302 } | |
303 | |
304 bool DrawPolygon::GetInverseTransform(gfx::Transform* transform) const { | |
305 return original_ref->quadTransform().GetInverse(transform); | |
306 } | |
307 | |
308 } // namespace cc | |
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