![](/img/trans.png)
[英]Is It More Efficient to Use GL_TRIANGLE_STRIP or Indexed GL_TRIANGLES to a Draw a Dynamic Number of Quads
[英]GL_TRIANGLES instead of GL_QUADS
我想修改用于生成3D球体的代码,因此它使用三角形而不是四边形进行绘制。 问题是,像往常一样,我遇到了一些错误-“向量迭代器不可递增”。 它出什么问题了?
SolidSphere(float radius, unsigned int rings, unsigned int sectors)
{
float const R = 1.0f / (float)(rings-1);
float const S = 1.0f / (float)(sectors-1);
int r, s;
vertices.resize(rings * sectors * 3);
normals.resize(rings * sectors * 3);
texcoords.resize(rings * sectors * 2);
std::vector<GLfloat>::iterator v = vertices.begin();
std::vector<GLfloat>::iterator n = normals.begin();
std::vector<GLfloat>::iterator t = texcoords.begin();
for(r = 0; r < rings; r++) for(s = 0; s < sectors; s++) {
float const x = sinf(M_PI * r * R) * cosf(2 * M_PI * s * S);
float const y = sinf(-M_PI_2 + M_PI * r * R );
float const z = sinf(2.0f * M_PI * s * S) * sinf( M_PI * r * R );
*t++ = s*S;
*t++ = r*R;
*v++ = x * radius;
*v++ = y * radius;
*v++ = z * radius;
*n++ = x;
*n++ = y;
*n++ = z;
}
indices.resize(rings * sectors * 4);
std::vector<GLushort>::iterator i = indices.begin();
for(r = 0; r < rings-1; r++) for(s = 0; s < sectors-1; s++) {
/* triangles -- not working!
*i++ = r * sectors + s;
*i++ = (r + 1) * sectors + (s + 1);
*i++ = r * sectors + (s + 1);
*i++ = r * sectors + s;
*i++ = (r + 1) * sectors + s;
*i++ = (r + 1) * sectors + (s + 1); */
/* quads */
*i++ = r * sectors + s;
*i++ = r * sectors + (s+1);
*i++ = (r+1) * sectors + (s+1);
*i++ = (r+1) * sectors + s;
}
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.