1 | /* -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil -*- */ |
---|
2 | /* |
---|
3 | * ---------------------------------------------------------------------- |
---|
4 | * ConvexPolygon.cpp: convex polygon class |
---|
5 | * |
---|
6 | * ====================================================================== |
---|
7 | * AUTHOR: Wei Qiao <qiaow@purdue.edu> |
---|
8 | * Purdue Rendering and Perceptualization Lab (PURPL) |
---|
9 | * |
---|
10 | * Copyright (c) 2004-2012 HUBzero Foundation, LLC |
---|
11 | * |
---|
12 | * See the file "license.terms" for information on usage and |
---|
13 | * redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
---|
14 | * ====================================================================== |
---|
15 | */ |
---|
16 | #include <assert.h> |
---|
17 | |
---|
18 | #include <GL/glew.h> |
---|
19 | |
---|
20 | #include "ConvexPolygon.h" |
---|
21 | #include "Trace.h" |
---|
22 | |
---|
23 | using namespace vrmath; |
---|
24 | |
---|
25 | ConvexPolygon::ConvexPolygon(VertexVector newvertices) |
---|
26 | { |
---|
27 | vertices.insert(vertices.begin(), newvertices.begin(), newvertices.end()); |
---|
28 | } |
---|
29 | |
---|
30 | void |
---|
31 | ConvexPolygon::transform(const Matrix4x4d& mat) |
---|
32 | { |
---|
33 | VertexVector tmp = vertices; |
---|
34 | vertices.clear(); |
---|
35 | |
---|
36 | for (unsigned int i = 0; i < tmp.size(); i++) { |
---|
37 | Vector4f vec = tmp[i]; |
---|
38 | vertices.push_back(mat.transform(vec)); |
---|
39 | } |
---|
40 | } |
---|
41 | |
---|
42 | void |
---|
43 | ConvexPolygon::translate(const Vector4f& shift) |
---|
44 | { |
---|
45 | VertexVector tmp = vertices; |
---|
46 | vertices.clear(); |
---|
47 | |
---|
48 | for (unsigned int i = 0; i < tmp.size(); i++) { |
---|
49 | Vector4f vec = tmp[i]; |
---|
50 | vertices.push_back(vec + shift); |
---|
51 | } |
---|
52 | } |
---|
53 | |
---|
54 | #define SIGN_DIFFERS(x, y) \ |
---|
55 | ( ((x) < 0.0 && (y) > 0.0) || ((x) > 0.0 && (y) < 0.0) ) |
---|
56 | |
---|
57 | bool |
---|
58 | ConvexPolygon::clip(nv::Plane& clipPlane, bool copyToTexcoord) |
---|
59 | { |
---|
60 | if (vertices.size() == 0) { |
---|
61 | ERROR("polygon has no vertices"); |
---|
62 | return false; |
---|
63 | } |
---|
64 | |
---|
65 | VertexVector clippedVerts; |
---|
66 | clippedVerts.reserve(2 * vertices.size()); |
---|
67 | |
---|
68 | // The algorithm is as follows: for each vertex |
---|
69 | // in the current poly, check to see which |
---|
70 | // half space it is in: clipped (outside) or inside. |
---|
71 | // If the previous vertex was in the other |
---|
72 | // half space, find the intersection of that edge |
---|
73 | // with the clip plane and add that intersection |
---|
74 | // point to the new list of vertices. If the |
---|
75 | // current vertex is in the inside half-space, |
---|
76 | // add it to the new list as well. |
---|
77 | |
---|
78 | Vector4f plane = clipPlane.getCoeffs(); |
---|
79 | |
---|
80 | // This implementation is based on the Mesa 3D library (MIT license) |
---|
81 | int v1 = 0; |
---|
82 | // dot product >= 0 on/inside half-space, < 0 outside half-space |
---|
83 | float dot1 = vertices[v1] * plane; |
---|
84 | for (unsigned int i = 1; i <= vertices.size(); i++) { |
---|
85 | int v2 = (i == vertices.size()) ? 0 : i; |
---|
86 | float dot2 = vertices[v2] * plane; |
---|
87 | if (dot1 >= 0.0) { |
---|
88 | // on/inside |
---|
89 | clippedVerts.push_back(vertices[v1]); |
---|
90 | } |
---|
91 | if (SIGN_DIFFERS(dot1, dot2)) { |
---|
92 | if (dot1 < 0.0) { |
---|
93 | // outside -> inside |
---|
94 | double t = dot1 / (dot1 - dot2); |
---|
95 | clippedVerts.push_back(vlerp(vertices[v1], vertices[v2], t)); |
---|
96 | } else { |
---|
97 | // inside -> outside |
---|
98 | double t = dot2 / (dot2 - dot1); |
---|
99 | clippedVerts.push_back(vlerp(vertices[v2], vertices[v1], t)); |
---|
100 | } |
---|
101 | } |
---|
102 | dot1 = dot2; |
---|
103 | v1 = v2; |
---|
104 | } |
---|
105 | |
---|
106 | vertices.clear(); |
---|
107 | |
---|
108 | if (clippedVerts.size() < 3) { |
---|
109 | texcoords.clear(); |
---|
110 | return false; |
---|
111 | } else { |
---|
112 | vertices.insert(vertices.begin(), |
---|
113 | clippedVerts.begin(), |
---|
114 | clippedVerts.end()); |
---|
115 | |
---|
116 | if (copyToTexcoord) |
---|
117 | copyVerticesToTexcoords(); |
---|
118 | |
---|
119 | return true; |
---|
120 | } |
---|
121 | } |
---|
122 | |
---|
123 | #undef SIGN_DIFFERS |
---|
124 | |
---|
125 | void |
---|
126 | ConvexPolygon::copyVerticesToTexcoords() |
---|
127 | { |
---|
128 | if (texcoords.size() > 0) |
---|
129 | texcoords.clear(); |
---|
130 | |
---|
131 | for (unsigned int i = 0; i < vertices.size(); i++) { |
---|
132 | texcoords.push_back(vertices[i]); |
---|
133 | } |
---|
134 | } |
---|
135 | |
---|
136 | void |
---|
137 | ConvexPolygon::emit(bool useTexture) |
---|
138 | { |
---|
139 | if (vertices.size() >= 3) { |
---|
140 | for (unsigned int i = 0; i < vertices.size(); i++) { |
---|
141 | if (useTexture) { |
---|
142 | glTexCoord4fv((float *)&(texcoords[i])); |
---|
143 | //glTexCoord4fv((float *)&(vertices[i])); |
---|
144 | } |
---|
145 | glVertex4fv((float *)&(vertices[i])); |
---|
146 | } |
---|
147 | } else { |
---|
148 | WARN("No polygons to render"); |
---|
149 | } |
---|
150 | } |
---|
151 | |
---|
152 | void |
---|
153 | ConvexPolygon::emit(bool useTexture, const Vector3f& shift, const Vector3f& scale) |
---|
154 | { |
---|
155 | if (vertices.size() >= 3) { |
---|
156 | for (unsigned int i = 0; i < vertices.size(); i++) { |
---|
157 | if (useTexture) { |
---|
158 | glTexCoord4fv((float *)&(vertices[i])); |
---|
159 | } |
---|
160 | Vector4f tmp = (vertices[i]); |
---|
161 | Vector4f shift_4d = Vector4f(shift.x, shift.y, shift.z, 0); |
---|
162 | tmp = tmp + shift_4d; |
---|
163 | tmp.x = tmp.x * scale.x; |
---|
164 | tmp.y = tmp.y * scale.y; |
---|
165 | tmp.z = tmp.z * scale.z; |
---|
166 | glVertex4fv((float *)(&tmp)); |
---|
167 | } |
---|
168 | } else { |
---|
169 | WARN("No polygons to render"); |
---|
170 | } |
---|
171 | } |
---|