Minecraft克隆的最佳盒子选择方法 [英] Best box selection method for a Minecraft clone
问题描述
作为我的第一个OpenGL项目，我正在制作Minecraft副本，并停留在选择框部分.进行可靠的盒子选择的最佳方法是什么?
I'm making a Minecraft clone as my very first OpenGL project and am stuck at the box selection part. What would be the best method to make a reliable box selection?
我一直在研究一些AABB算法，但是没有一个能很好地解释它们的确切功能(尤其是经过超级调整的算法)，并且我不想使用我不了解的东西.
I've been going through some AABB algorithms, but none of them explain well enough what they exactly do (especially the super tweaked ones) and I don't want to use stuff I don't understand.
由于世界是由多维数据集组成的，所以我使用八叉树消除了射线投射计算中的某些应变，基本上我唯一需要的就是此函数:
Since the world is composed of cubes I used octrees to remove some strain on ray cast calculations, basically the only thing I need is this function:
float cube_intersect(Vector ray, Vector origin, Vector min, Vector max)
{
//???
}
射线和原点很容易获得
Vector ray, origin, point_far;
double mx, my, mz;
gluUnProject(viewport[2]/2, viewport[3]/2, 1.0, (double*)modelview, (double*)projection, viewport, &mx, &my, &mz);
point_far = Vector(mx, my, mz);
gluUnProject(viewport[2]/2, viewport[3]/2, 0.0, (double*)modelview, (double*)projection, viewport, &mx, &my, &mz);
origin = Vector(mx, my, mz);
ray = point_far-origin;
min和max是立方体的相对角.
min and max are the opposite corners of a cube.
考虑到即使使用八叉树，我也必须检查的多维数据集数量，我什至不确定这是否是正确的方法.
I'm not even sure this is the right way to do this, considering the number of cubes I'd have to check, even with octrees.
我也尝试过gluProject，它可以工作，但是非常不可靠，并且无法为我提供选定的立方体面.
I've also tried gluProject, it works, but is very unreliable and doesn't give me the selected face of the cube.
编辑
这就是我要做的:用射线计算空间中的位置:
So this is what I've done: calculate a position in space with the ray:
float t = 0;
for(int i=0; i<10; i++)
{
Vector p = ray*t+origin;
while(visible octree)
{
if(p inside octree)
{
// then call recursive function until a cube is found
break;
}
octree = octree->next;
}
if(found a cube)
{
break;
}
t += .5;
}
实际上速度惊人，并且在找到第一个多维数据集后便停止了运行.
It's actually surprisingly fast and stops after the first found cube.
如您所见，射线必须先经过多个八叉树才能找到一个立方体(实际上是在空间中的位置)-屏幕中间有一个十字准线.增量步长越低，选择越精确，但速度也越慢.
As you can see the ray has to go trough multiple octrees before it finds a cube (actually a position in space) - there is a crosshair in the middle of the screen. The lower the increment step the more precise the selection, but also slower.
推荐答案
使用框作为原语在内存需求和处理能力方面过高. 多维数据集非常适合渲染，甚至在那里，您还可以找到更高级的算法，从而为您提供更好的最终图像(行进多维数据集).从这种意义上来说，Minecraft的图形非常原始，因为体素渲染已经存在了很长时间，并且已经取得了重大进展.
Working with boxes as primitives is overkill in memory requirements and processing power. Cubes are fine for rendering and even there you can find more advanced algorithms that give you a better final image (Marching cubes). Minecraft's graphics are very primitive in this sense as voxel rendering has been around for a long time and significant progress has been made.
基本上，您应该利用所有盒子均等间距且大小相同的事实.这些称为体素. 与您所拥有的相比，网格中的光线投射是微不足道的-宽相八叉树和窄相AABB测试.我建议您对体素和体素集碰撞检测/光线投射进行一些研究，因为您会发现这两种算法都更易于实现且运行速度更快.
Basically you should exploit the fact that all your boxes are equally spaced and of the same size. These are called voxels. Raycasting in a grid is trivial in comparison to what you have - a broad-phase oct-tree and a narrow phase AABB test. I suggest you research a bit on voxels and voxel set collision detection/raycasting as you will find both algorithms that are easier to implement and that would run faster.
这篇关于Minecraft克隆的最佳盒子选择方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
