【发布时间】：2016-10-07 10:24:00
【问题描述】：
我正在尝试“填充”我绘制的某些几何图形的表面。我正在使用GL_TRIANGLE_FAN 原语。 （例如：1 个枢纽（中心）点和 12 个其他点）。我已经计算了区间 0-1 中每个顶点的纹理坐标。但结果我得到了这个 ，它有点困惑。我希望得到这样的结果 image 。请帮忙，这里有什么问题？
如何在这种三角测量中计算正确的纹理坐标（GL_TRIANGLE_FAN）
image中的红点是我的积分
*代码 - 片段：
assert(("CROSS type intersection needs only 5 vertices : center point and "
"rest points in anticlockwise order", (lp->size() > 5) && (lp->size() < 5)));
osg::Vec3 vAlong_1,vAlong_2;
vAlong_1 = (*lp)[1] - (*lp)[4];
vAlong_2 = (*lp)[1] - (*lp)[2];
eps = ((*lp)[2] - (*lp)[4]).length() * 0.2 / 2;
vAlong_1.normalize();
vAlong_2.normalize();
_edgeCoords->push_back((*lp)[0]);
_edgeCoords->push_back((*lp)[1]);
if (CMF::euclidDistance((*lp)[0],(*lp)[1]) <= CMF::euclidDistance((*lp)[0],(*lp)[2])) {
float cosAlpha = -(vAlong_1 * vAlong_2);
float extraLength = ((*lp)[2] - (*lp)[1]).length() * cosAlpha;
_edgeCoords->push_back((*lp)[1] + vAlong_1 * (eps + extraLength));
_edgeCoords->push_back((*lp)[2] + vAlong_1 * eps);
} else {
float cosAlpha = (vAlong_1 * vAlong_2);
float extraLength = ((*lp)[2] - (*lp)[1]).length() * cosAlpha;
_edgeCoords->push_back((*lp)[1] + vAlong_1 * eps);
_edgeCoords->push_back((*lp)[2] + vAlong_1 * (eps + extraLength));
}
_edgeCoords->push_back((*lp)[2]);
if (CMF::euclidDistance((*lp)[0],(*lp)[2]) <= CMF::euclidDistance((*lp)[0],(*lp)[3])) {
float cosAlpha = -(vAlong_1 * vAlong_2);
float extraLength = ((*lp)[3] - (*lp)[2]).length() * cosAlpha;
_edgeCoords->push_back((*lp)[2] - vAlong_2 * (eps + extraLength));
_edgeCoords->push_back((*lp)[3] - vAlong_2 * eps);
} else {
float cosAlpha = (vAlong_1 * vAlong_2);
float extraLength = ((*lp)[3] - (*lp)[2]).length() * cosAlpha;
_edgeCoords->push_back((*lp)[2] - vAlong_2 * eps);
_edgeCoords->push_back((*lp)[3] - vAlong_2 * (eps + extraLength));
}
_edgeCoords->push_back((*lp)[3]);
if (CMF::euclidDistance((*lp)[0],(*lp)[3]) <= CMF::euclidDistance((*lp)[0],(*lp)[4])) {
float cosAlpha = -(vAlong_1 * vAlong_2);
float extraLength = ((*lp)[4] - (*lp)[3]).length() * cosAlpha;
_edgeCoords->push_back((*lp)[3] - vAlong_1 * (eps + extraLength));
_edgeCoords->push_back((*lp)[4] - vAlong_1 * eps);
} else {
float cosAlpha = (vAlong_1 * vAlong_2);
float extraLength = ((*lp)[4] - (*lp)[3]).length() * cosAlpha;
_edgeCoords->push_back((*lp)[3] - vAlong_1 * eps);
_edgeCoords->push_back((*lp)[4] - vAlong_1 * (eps + extraLength));
}
_edgeCoords->push_back((*lp)[4]);
if (CMF::euclidDistance((*lp)[0],(*lp)[1]) <= CMF::euclidDistance((*lp)[0],(*lp)[4])) {
float cosAlpha = -(vAlong_1 * vAlong_2);
float extraLength = ((*lp)[4] - (*lp)[1]).length() * cosAlpha;
_edgeCoords->push_back((*lp)[4] + vAlong_2 * eps);
_edgeCoords->push_back((*lp)[1] + vAlong_2 * (eps + extraLength));
} else {
float cosAlpha = (vAlong_1 * vAlong_2);
float extraLength = ((*lp)[4] - (*lp)[1]).length() * cosAlpha;
_edgeCoords->push_back((*lp)[4] + vAlong_2 * (eps + extraLength));
_edgeCoords->push_back((*lp)[1] + vAlong_2 * eps);
}
_edgeCoords->push_back((*lp)[1]);
_tCoords->push_back(osg::Vec2(0.5,0.5));
_tCoords->push_back(osg::Vec2(0.666,0.666));
_tCoords->push_back(osg::Vec2(0.666,1.0));
_tCoords->push_back(osg::Vec2(0.333,1.0));
_tCoords->push_back(osg::Vec2(0.333,0.666));
_tCoords->push_back(osg::Vec2(0.0,0.666));
_tCoords->push_back(osg::Vec2(0.0,0.333));
_tCoords->push_back(osg::Vec2(0.333,0.333));
_tCoords->push_back(osg::Vec2(0.333,0.0));
_tCoords->push_back(osg::Vec2(0.666,0.0));
_tCoords->push_back(osg::Vec2(0.666,0.333));
_tCoords->push_back(osg::Vec2(1.0,0.333));
_tCoords->push_back(osg::Vec2(1.0,0.666));
_tCoords->push_back(osg::Vec2(0.666,0.666));
【问题讨论】：
-
您可以发布生成图像的代码吗？
-
@CherkesgillerTural 我很困惑 - 当安装在风扇上时，您想要的最终结果是什么？您已经发布了原始纹理；你想把每个数字都装到相同大小的风扇上，并丢弃黄色的位吗？
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是的，看起来纹理图像的形状与您的几何形状不相似，所以它会变形......
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@willywonkadailyblah 是的，我想要你在帖子中提到的结果。我已经更改了所需结果的图像。我该怎么做
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我相信你的几何形状是错误的——如果你想要统一大小的数字，那么几何形状必须与之匹配，否则纹理的拉伸是不均匀的，因此会产生伪影。除非你不这样做？
标签： algorithm opengl graphics directx texture-mapping