summaryrefslogtreecommitdiff
path: root/graphics/asymptote/bezierpatch.h
blob: 75ba7a66f9cd09b2a909d07be0cbf8e4bf9be34e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
/*****
 * bezierpatch.h
 * Authors: John C. Bowman and Jesse Frohlich
 *
 * Render Bezier patches and triangles.
 *****/

#ifndef BEZIERPATCH_H
#define BEZIERPATCH_H

#include "drawelement.h"

namespace camp {

#ifdef HAVE_GL

struct BezierPatch
{
  vertexBuffer data;

  bool transparent;
  bool color;
  double epsilon;
  double Epsilon;
  double res2;
  double Res2; // Reduced resolution for Bezier triangles flatness test.
  typedef GLuint (vertexBuffer::*vertexFunction)(const triple &v,
                                                 const triple& n);
  vertexFunction pvertex;
  bool Onscreen;

  void init(double res);

  triple normal(triple left3, triple left2, triple left1, triple middle,
                triple right1, triple right2, triple right3) {
    triple lp=3.0*(left1-middle);
    triple rp=3.0*(right1-middle);

    triple n=cross(rp,lp);
    if(abs2(n) > epsilon)
      return n;

    triple lpp=bezierPP(middle,left1,left2);
    triple rpp=bezierPP(middle,right1,right2);

    n=cross(rpp,lp)+cross(rp,lpp);
    if(abs2(n) > epsilon)
      return n;

    triple lppp=bezierPPP(middle,left1,left2,left3);
    triple rppp=bezierPPP(middle,right1,right2,right3);

    n=cross(rpp,lpp)+cross(rppp,lp)+cross(rp,lppp);
    if(abs2(n) > epsilon)
      return n;

    n=cross(rppp,lpp)+cross(rpp,lppp);
    if(abs2(n) > epsilon)
      return n;

    return cross(rppp,lppp);
  }

  // Return the differential of the Bezier curve p0,p1,p2,p3 at 0
  triple differential(triple p0, triple p1, triple p2, triple p3) {
    triple p=p1-p0;
    if(abs2(p) > epsilon)
      return p;

    p=bezierPP(p0,p1,p2);
    if(abs2(p) > epsilon)
      return p;

    return bezierPPP(p0,p1,p2,p3);
  }

  // Determine the flatness of a Bezier patch.
  pair Distance(const triple *p) {
    triple p0=p[0];
    triple p3=p[3];
    triple p12=p[12];
    triple p15=p[15];

    // Check the horizontal flatness.
    double h=Flatness(p0,p12,p3,p15);
    // Check straightness of the horizontal edges and interior control curves.
    h=max(h,Straightness(p0,p[4],p[8],p12));
    h=max(h,Straightness(p[1],p[5],p[9],p[13]));
    h=max(h,Straightness(p[2],p[6],p[10],p[14]));
    h=max(h,Straightness(p3,p[7],p[11],p15));

    // Check the vertical flatness.
    double v=Flatness(p0,p3,p12,p15);
    // Check straightness of the vertical edges and interior control curves.
    v=max(v,Straightness(p0,p[1],p[2],p3));
    v=max(v,Straightness(p[4],p[5],p[6],p[7]));
    v=max(v,Straightness(p[8],p[9],p[10],p[11]));
    v=max(v,Straightness(p12,p[13],p[14],p15));

    return pair(h,v);
  }

  struct Split3 {
    triple m0,m2,m3,m4,m5;
    Split3() {}
    Split3(triple z0, triple c0, triple c1, triple z1) {
      m0=0.5*(z0+c0);
      triple m1=0.5*(c0+c1);
      m2=0.5*(c1+z1);
      m3=0.5*(m0+m1);
      m4=0.5*(m1+m2);
      m5=0.5*(m3+m4);
    }
  };

  // Approximate bounds by bounding box of control polyhedron.
  bool offscreen(size_t n, const triple *v) {
    if(bbox2(n,v).offscreen()) {
      Onscreen=false;
      return true;
    }
    return false;
  }

  virtual void render(const triple *p, bool straight, GLfloat *c0=NULL);
  void render(const triple *p,
              GLuint I0, GLuint I1, GLuint I2, GLuint I3,
              triple P0, triple P1, triple P2, triple P3,
              bool flat0, bool flat1, bool flat2, bool flat3,
              GLfloat *C0=NULL, GLfloat *C1=NULL, GLfloat *C2=NULL,
              GLfloat *C3=NULL);

  void append() {
    if(transparent)
      transparentData.Append(data);
    else {
      if(color)
        colorData.Append(data);
      else
        materialData.append(data);
    }
  }

  virtual void notRendered() {
    if(transparent)
      transparentData.rendered=false;
    else {
      if(color)
        colorData.rendered=false;
      else
        materialData.rendered=false;
    }
  }

  void queue(const triple *g, bool straight, double ratio, bool Transparent,
             GLfloat *colors=NULL) {
    data.clear();
    notRendered();
    Onscreen=true;
    transparent=Transparent;
    color=colors;
    init(pixel*ratio);
    render(g,straight,colors);
  }

};

struct BezierTriangle : public BezierPatch {
public:
  BezierTriangle() : BezierPatch() {}

  double Distance(const triple *p) {
    triple p0=p[0];
    triple p6=p[6];
    triple p9=p[9];

    // Check how far the internal point is from the centroid of the vertices.
    double d=abs2((p0+p6+p9)*third-p[4]);

    // Determine how straight the edges are.
    d=max(d,Straightness(p0,p[1],p[3],p6));
    d=max(d,Straightness(p0,p[2],p[5],p9));
    return max(d,Straightness(p6,p[7],p[8],p9));
  }

  void render(const triple *p, bool straight, GLfloat *c0=NULL);
  void render(const triple *p,
              GLuint I0, GLuint I1, GLuint I2,
              triple P0, triple P1, triple P2,
              bool flat0, bool flat1, bool flat2,
              GLfloat *C0=NULL, GLfloat *C1=NULL, GLfloat *C2=NULL);
};

struct Triangles : public BezierPatch {
public:
  Triangles() : BezierPatch() {}

  void queue(size_t nP, const triple* P, size_t nN, const triple* N,
             size_t nC, const prc::RGBAColour* C, size_t nI,
             const uint32_t (*PI)[3], const uint32_t (*NI)[3],
             const uint32_t (*CI)[3], bool transparent);

  void append() {
    if(transparent)
      transparentData.Append(data);
    else
      triangleData.Append(data);
  }

  void notRendered() {
    if(transparent)
      transparentData.rendered=false;
    else
      triangleData.rendered=false;
  }

};

extern void sortTriangles();

#endif

} //namespace camp

#endif