[2798] | 1 | /* -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil -*- */ |
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[978] | 2 | /* |
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| 3 | * ---------------------------------------------------------------------- |
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| 4 | * ConvexPolygon.cpp: convex polygon class |
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| 5 | * |
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| 6 | * ====================================================================== |
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| 7 | * AUTHOR: Wei Qiao <qiaow@purdue.edu> |
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| 8 | * Purdue Rendering and Perceptualization Lab (PURPL) |
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| 9 | * |
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[3502] | 10 | * Copyright (c) 2004-2013 HUBzero Foundation, LLC |
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[978] | 11 | * |
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| 12 | * See the file "license.terms" for information on usage and |
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| 13 | * redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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| 14 | * ====================================================================== |
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| 15 | */ |
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[2822] | 16 | #include <assert.h> |
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| 17 | |
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[2823] | 18 | #include <GL/glew.h> |
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[2822] | 19 | |
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[978] | 20 | #include "ConvexPolygon.h" |
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[1984] | 21 | #include "Trace.h" |
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[978] | 22 | |
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[3492] | 23 | using namespace vrmath; |
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| 24 | |
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[2822] | 25 | ConvexPolygon::ConvexPolygon(VertexVector newvertices) |
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| 26 | { |
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[978] | 27 | vertices.insert(vertices.begin(), newvertices.begin(), newvertices.end()); |
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| 28 | } |
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| 29 | |
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[2822] | 30 | void |
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[3492] | 31 | ConvexPolygon::transform(const Matrix4x4d& mat) |
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[2822] | 32 | { |
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[978] | 33 | VertexVector tmp = vertices; |
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| 34 | vertices.clear(); |
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| 35 | |
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| 36 | for (unsigned int i = 0; i < tmp.size(); i++) { |
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[3492] | 37 | Vector4f vec = tmp[i]; |
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[978] | 38 | vertices.push_back(mat.transform(vec)); |
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| 39 | } |
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| 40 | } |
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| 41 | |
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[2822] | 42 | void |
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[3492] | 43 | ConvexPolygon::translate(const Vector4f& shift) |
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[2822] | 44 | { |
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[978] | 45 | VertexVector tmp = vertices; |
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| 46 | vertices.clear(); |
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| 47 | |
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| 48 | for (unsigned int i = 0; i < tmp.size(); i++) { |
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[3492] | 49 | Vector4f vec = tmp[i]; |
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| 50 | vertices.push_back(vec + shift); |
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[978] | 51 | } |
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| 52 | } |
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| 53 | |
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[3362] | 54 | #define SIGN_DIFFERS(x, y) \ |
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| 55 | ( ((x) < 0.0 && (y) > 0.0) || ((x) > 0.0 && (y) < 0.0) ) |
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| 56 | |
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| 57 | bool |
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[3492] | 58 | ConvexPolygon::clip(nv::Plane& clipPlane, bool copyToTexcoord) |
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[2822] | 59 | { |
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[978] | 60 | if (vertices.size() == 0) { |
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[3452] | 61 | ERROR("polygon has no vertices"); |
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[3362] | 62 | return false; |
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[978] | 63 | } |
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[3362] | 64 | |
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[978] | 65 | VertexVector clippedVerts; |
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| 66 | clippedVerts.reserve(2 * vertices.size()); |
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| 67 | |
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| 68 | // The algorithm is as follows: for each vertex |
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| 69 | // in the current poly, check to see which |
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[3362] | 70 | // half space it is in: clipped (outside) or inside. |
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[978] | 71 | // If the previous vertex was in the other |
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[3362] | 72 | // half space, find the intersection of that edge |
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| 73 | // with the clip plane and add that intersection |
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[978] | 74 | // point to the new list of vertices. If the |
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[3362] | 75 | // current vertex is in the inside half-space, |
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[978] | 76 | // add it to the new list as well. |
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| 77 | |
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[3492] | 78 | Vector4f plane = clipPlane.getCoeffs(); |
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[978] | 79 | |
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[3362] | 80 | // This implementation is based on the Mesa 3D library (MIT license) |
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| 81 | int v1 = 0; |
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| 82 | // dot product >= 0 on/inside half-space, < 0 outside half-space |
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| 83 | float dot1 = vertices[v1] * plane; |
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| 84 | for (unsigned int i = 1; i <= vertices.size(); i++) { |
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| 85 | int v2 = (i == vertices.size()) ? 0 : i; |
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| 86 | float dot2 = vertices[v2] * plane; |
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| 87 | if (dot1 >= 0.0) { |
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| 88 | // on/inside |
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| 89 | clippedVerts.push_back(vertices[v1]); |
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[978] | 90 | } |
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[3362] | 91 | if (SIGN_DIFFERS(dot1, dot2)) { |
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| 92 | if (dot1 < 0.0) { |
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| 93 | // outside -> inside |
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| 94 | double t = dot1 / (dot1 - dot2); |
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| 95 | clippedVerts.push_back(vlerp(vertices[v1], vertices[v2], t)); |
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| 96 | } else { |
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| 97 | // inside -> outside |
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| 98 | double t = dot2 / (dot2 - dot1); |
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| 99 | clippedVerts.push_back(vlerp(vertices[v2], vertices[v1], t)); |
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| 100 | } |
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[978] | 101 | } |
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[3362] | 102 | dot1 = dot2; |
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| 103 | v1 = v2; |
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[978] | 104 | } |
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| 105 | |
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| 106 | vertices.clear(); |
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| 107 | |
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[3362] | 108 | if (clippedVerts.size() < 3) { |
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| 109 | texcoords.clear(); |
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| 110 | return false; |
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| 111 | } else { |
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| 112 | vertices.insert(vertices.begin(), |
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| 113 | clippedVerts.begin(), |
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| 114 | clippedVerts.end()); |
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| 115 | |
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| 116 | if (copyToTexcoord) |
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| 117 | copyVerticesToTexcoords(); |
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| 118 | |
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| 119 | return true; |
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| 120 | } |
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[978] | 121 | } |
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| 122 | |
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[3362] | 123 | #undef SIGN_DIFFERS |
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| 124 | |
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[2822] | 125 | void |
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[2877] | 126 | ConvexPolygon::copyVerticesToTexcoords() |
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[2822] | 127 | { |
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| 128 | if (texcoords.size() > 0) |
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[978] | 129 | texcoords.clear(); |
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| 130 | |
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[2822] | 131 | for (unsigned int i = 0; i < vertices.size(); i++) { |
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[978] | 132 | texcoords.push_back(vertices[i]); |
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| 133 | } |
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| 134 | } |
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| 135 | |
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[2822] | 136 | void |
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[2877] | 137 | ConvexPolygon::emit(bool useTexture) |
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[978] | 138 | { |
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| 139 | if (vertices.size() >= 3) { |
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[2822] | 140 | for (unsigned int i = 0; i < vertices.size(); i++) { |
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[2877] | 141 | if (useTexture) { |
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[978] | 142 | glTexCoord4fv((float *)&(texcoords[i])); |
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| 143 | //glTexCoord4fv((float *)&(vertices[i])); |
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| 144 | } |
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| 145 | glVertex4fv((float *)&(vertices[i])); |
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| 146 | } |
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[3362] | 147 | } else { |
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[3452] | 148 | WARN("No polygons to render"); |
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[3362] | 149 | } |
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[978] | 150 | } |
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| 151 | |
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| 152 | void |
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[3492] | 153 | ConvexPolygon::emit(bool useTexture, const Vector3f& shift, const Vector3f& scale) |
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[978] | 154 | { |
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| 155 | if (vertices.size() >= 3) { |
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[2822] | 156 | for (unsigned int i = 0; i < vertices.size(); i++) { |
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[2877] | 157 | if (useTexture) { |
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[978] | 158 | glTexCoord4fv((float *)&(vertices[i])); |
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| 159 | } |
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[3492] | 160 | Vector4f tmp = (vertices[i]); |
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| 161 | Vector4f shift_4d = Vector4f(shift.x, shift.y, shift.z, 0); |
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[978] | 162 | tmp = tmp + shift_4d; |
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| 163 | tmp.x = tmp.x * scale.x; |
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| 164 | tmp.y = tmp.y * scale.y; |
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| 165 | tmp.z = tmp.z * scale.z; |
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| 166 | glVertex4fv((float *)(&tmp)); |
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| 167 | } |
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[3362] | 168 | } else { |
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[3452] | 169 | WARN("No polygons to render"); |
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[978] | 170 | } |
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| 171 | } |
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