demos/boxes/roundedbox.cpp

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  41
  42 #include "roundedbox.h"
  43
  44 //============================================================================//
  45 //                                P3T2N3Vertex                                //
  46 //============================================================================//
  47
  48 VertexDescription P3T2N3Vertex::description[] = {
  49     {VertexDescription::Position, GL_FLOAT, SIZE_OF_MEMBER(P3T2N3Vertex, position) / sizeof(float), 0, 0},
  50     {VertexDescription::TexCoord, GL_FLOAT, SIZE_OF_MEMBER(P3T2N3Vertex, texCoord) / sizeof(float), sizeof(QVector3D), 0},
  51     {VertexDescription::Normal, GL_FLOAT, SIZE_OF_MEMBER(P3T2N3Vertex, normal) / sizeof(float), sizeof(QVector3D) + sizeof(QVector2D), 0},
  52
  53     {VertexDescription::Null, 0, 0, 0, 0},
  54 };
  55
  56 //============================================================================//
  57 //                                GLRoundedBox                                //
  58 //============================================================================//
  59
  60 float lerp(float a, float b, float t)
  61 {
  62     return a * (1.0f - t) + b * t;
  63 }
  64
  65 GLRoundedBox::GLRoundedBox(float r, float scale, int n)
  66     : GLTriangleMesh<P3T2N3Vertex, unsigned short>((n+2)*(n+3)*4, (n+1)*(n+1)*24+36+72*(n+1))
  67 {
  68     int vidx = 0, iidx = 0;
  69     int vertexCountPerCorner = (n + 2) * (n + 3) / 2;
  70
  71     P3T2N3Vertex *vp = m_vb.lock();
  72     unsigned short *ip = m_ib.lock();
  73
  74     if (!vp || !ip) {
  75         qWarning("GLRoundedBox::GLRoundedBox: Failed to lock vertex buffer and/or index buffer.");
  76         m_ib.unlock();
  77         m_vb.unlock();
  78         return;
  79     }
  80
  81     for (int corner = 0; corner < 8; ++corner) {
  82         QVector3D centre(corner & 1 ? 1.0f : -1.0f,
  83                 corner & 2 ? 1.0f : -1.0f,
  84                 corner & 4 ? 1.0f : -1.0f);
  85         int winding = (corner & 1) ^ ((corner >> 1) & 1) ^ (corner >> 2);
  86         int offsX = ((corner ^ 1) - corner) * vertexCountPerCorner;
  87         int offsY = ((corner ^ 2) - corner) * vertexCountPerCorner;
  88         int offsZ = ((corner ^ 4) - corner) * vertexCountPerCorner;
  89
  90         // Face polygons
  91         if (winding) {
  92             ip[iidx++] = vidx;
  93             ip[iidx++] = vidx + offsX;
  94             ip[iidx++] = vidx + offsY;
  95
  96             ip[iidx++] = vidx + vertexCountPerCorner - n - 2;
  97             ip[iidx++] = vidx + vertexCountPerCorner - n - 2 + offsY;
  98             ip[iidx++] = vidx + vertexCountPerCorner - n - 2 + offsZ;
  99
 100             ip[iidx++] = vidx + vertexCountPerCorner - 1;
 101             ip[iidx++] = vidx + vertexCountPerCorner - 1 + offsZ;
 102             ip[iidx++] = vidx + vertexCountPerCorner - 1 + offsX;
 103         }
 104
 105         for (int i = 0; i < n + 2; ++i) {
 106
 107             // Edge polygons
 108             if (winding && i < n + 1) {
 109                 ip[iidx++] = vidx + i + 1;
 110                 ip[iidx++] = vidx;
 111                 ip[iidx++] = vidx + offsY + i + 1;
 112                 ip[iidx++] = vidx + offsY;
 113                 ip[iidx++] = vidx + offsY + i + 1;
 114                 ip[iidx++] = vidx;
 115
 116                 ip[iidx++] = vidx + i;
 117                 ip[iidx++] = vidx + 2 * i + 2;
 118                 ip[iidx++] = vidx + i + offsX;
 119                 ip[iidx++] = vidx + 2 * i + offsX + 2;
 120                 ip[iidx++] = vidx + i + offsX;
 121                 ip[iidx++] = vidx + 2 * i + 2;
 122
 123                 ip[iidx++] = (corner + 1) * vertexCountPerCorner - 1 - i;
 124                 ip[iidx++] = (corner + 1) * vertexCountPerCorner - 2 - i;
 125                 ip[iidx++] = (corner + 1) * vertexCountPerCorner - 1 - i + offsZ;
 126                 ip[iidx++] = (corner + 1) * vertexCountPerCorner - 2 - i + offsZ;
 127                 ip[iidx++] = (corner + 1) * vertexCountPerCorner - 1 - i + offsZ;
 128                 ip[iidx++] = (corner + 1) * vertexCountPerCorner - 2 - i;
 129             }
 130
 131             for (int j = 0; j <= i; ++j) {
 132                 QVector3D normal = QVector3D(i - j, j, n + 1 - i).normalized();
 133                 QVector3D offset(0.5f - r, 0.5f - r, 0.5f - r);
 134                 QVector3D pos = centre * (offset + r * normal);
 135
 136                 vp[vidx].position = scale * pos;
 137                 vp[vidx].normal = centre * normal;
 138                 vp[vidx].texCoord = QVector2D(pos.x() + 0.5f, pos.y() + 0.5f);
 139
 140                 // Corner polygons
 141                 if (i < n + 1) {
 142                     ip[iidx++] = vidx;
 143                     ip[iidx++] = vidx + i + 2 - winding;
 144                     ip[iidx++] = vidx + i + 1 + winding;
 145                 }
 146                 if (i < n) {
 147                     ip[iidx++] = vidx + i + 1 + winding;
 148                     ip[iidx++] = vidx + i + 2 - winding;
 149                     ip[iidx++] = vidx + 2 * i + 4;
 150                 }
 151
 152                 ++vidx;
 153             }
 154         }
 155
 156     }
 157
 158     m_ib.unlock();
 159     m_vb.unlock();
 160 }
 161