Vector Vector::clamp(const Vector& vec, const Vector& min, const Vector& max)
{
return Vector(XMVectorClamp(vec.getXMVector(), min.getXMVector(), max.getXMVector()));
}
bool RayTraceDataGenerator::CalcIntersect(const XMVECTOR& p1, const XMVECTOR& n, XMVECTOR* nResult, XMVECTOR* intersectLocation, float* depth)
{
/*
// grid space
vec3 grid = floor( pos ); //向下取整将坐标在网格中使用
vec3 grid_step = sign( dir ); //获取dir(方向)的正负符号<-意思就是说获取网格的步进方向,虽然只是正负
vec3 corner = max( grid_step, vec3( 0.0 ) );//负号->0 //应该是最后在步进方向上产生的偏差值,但是原因不明
// ray space
vec3 inv = vec3( 1.0 ) / dir; //取倒数使得各个方向的比值倒过来
vec3 ratio = ( grid + corner - pos ) * inv;//corn+pos的小数部分
vec3 ratio_step = grid_step * inv;//不懂
//于是这个rayspace只是提供一个比值,来决定grid的步进么
// dda <-数值微分法
float hit = -1.0;
for ( int i = 0; i < 128; i++ ) {
if ( voxel( grid ) > 0.5 ) {
hit = 1.0;
break; //这里应该是可以直接退出循环的,感觉没什么区别
continue;
}
vec3 cp = step( ratio, ratio.yzx );//二维情况的搞清楚了,问题还有就是在三维空间上的扩展
mask = cp * ( vec3( 1.0 ) - cp.zxy );
grid += grid_step * mask;
ratio += ratio_step * mask;
}
center = grid + vec3( 0.5 );//中心形式表示(跟grid应该没区别吧0 0)
return dot(ratio - ratio_step,vec3(1.0)) * hit;//dot( ratio - ratio_step, mask ) * hit;
//这里关心的是hit的深度好像
*/
//p1是起点
XMVECTOR start = p1;
XMVECTOR dir = n;
XMVECTOR zero = XMVectorSetBinaryConstant(0, 0, 0, 0);
XMVECTOR one = XMVectorSetBinaryConstant(1, 1, 1, 1);
XMVECTOR grid;
XMVECTOR grid_step;
XMVECTOR grid_corner;
grid = XMVectorFloor(start);//实际上w分量为0应该就不影响了吧(
//好像DirectXMath没有提供Sign的函数(于是用了一个挺别扭的方法- -
//grid_step 就是 sign_dir
grid_step = DirectX::XMVectorOrInt(DirectX::XMVectorAndInt(dir, DirectX::XMVectorSplatSignMask()), DirectX::XMVectorSplatOne());
grid_corner = XMVectorClamp(grid_step, zero, one);
XMVECTOR inv;
XMVECTOR ratio;
XMVECTOR ratio_step;
inv = XMVectorReciprocal(dir);
ratio = XMVectorMultiply(XMVectorSubtract(XMVectorAdd(grid, grid_corner), start), inv);
ratio_step = XMVectorMultiply(grid_step, inv);
bool hit = false;
XMVECTOR cp;
XMVECTOR mask;
XMVECTOR ratioyzx;
XMVECTOR cpzxy;
XMFLOAT4 tmp1;
XMFLOAT4 tmp2;
int i;
for (i = 0; i < 128; ++i)//最大深度为128
{
XMStoreFloat4(&tmp1, grid);
/*
__try{
if (map->At(tmp1.x, tmp1.y, tmp1.z).TexType != -1)
{
hit = true;
break;
}
}
__except ((GetExceptionCode() == EXCEPTION_ARRAY_BOUNDS_EXCEEDED)?EXCEPTION_EXECUTE_HANDLER:EXCEPTION_CONTINUE_SEARCH)
{
//捕获越界错误作为跳出条件,看看有没有问题...
break;
}
*/
//理论上来说异常的话处理代价太大,还是判断一下range吧= =
if ((RangeCheck(tmp1.x, tmp1.y, tmp1.z)))
{
if (GetLocInfo(tmp1.x, tmp1.y, tmp1.z) != -1)
{
hit = true;
break;
}
}
/*
修正:发生越界的时候并不一定就要终止,需要考虑到从值域外射出的射线.....
不过就算不break效率应该也比原先的算法要高...(除了要限制一下最大遍历深度这方面
*/
XMStoreFloat4(&tmp1, ratio);
tmp2.x = tmp1.y; tmp2.y = tmp1.z; tmp2.z = tmp1.x;
ratioyzx = XMLoadFloat4(&tmp2);
cp = XMVectorAndInt(XMVectorGreaterOrEqual(ratioyzx, ratio), XMVectorSplatOne());//1 or 0
XMStoreFloat4(&tmp1, cp);
tmp2.x = tmp1.z; tmp2.y = tmp1.x; tmp2.z = tmp1.y;
cpzxy = XMLoadFloat4(&tmp2);
mask = XMVectorMultiply(cp, XMVectorSubtract(one, cpzxy));
grid += XMVectorMultiply(grid_step, mask);
ratio += XMVectorMultiply(ratio_step, mask);
}
if (hit)
{
XMFLOAT4 result;
result = tmp1; //所在方块
if (i == 0)
{
//这是在方块内部的情况
result.w = -1;
return false;
}
XMVECTOR ftmp;
ftmp = XMVectorSubtract(ratio, ratio_step);//因为取的只是mask方向的值,所以step在这里没必要乘mask
*depth = XMVectorGetX(DirectX::XMVector3Dot(ftmp, mask));
ftmp = XMVectorAdd(XMVectorScale(dir,*depth) , p1);
XMStoreFloat4(&tmp1, ftmp);
//需要全部反过来,因为上面的式子没有取反
*intersectLocation = ftmp;
result = tmp1;
result.w = 0;
XMVECTOR normal;
normal = XMVectorMultiply(mask, grid_step);
XMStoreFloat4(&tmp1, normal);
//需要全部反过来,因为上面的式子没有取反
if (tmp1.x > 0.5)
{
//法向量为1,0,0,后方
*nResult = XMVectorSetBinaryConstant(1, 0, 0, 0);
}
else if (tmp1.x < -0.5)
{
//法向量为-1,0,0,前方
*nResult = XMVectorSetBinaryConstant(-1, 0, 0, 0);
}
else if (tmp1.y < -0.5)
{
//法向量为0,-1,0,右方
*nResult = XMVectorSetBinaryConstant(0, -1, 0, 0);
}
else if (tmp1.y > 0.5)
{
//法向量为0,1,0,左方
*nResult = XMVectorSetBinaryConstant(0, 1, 0, 0);
}
else if (tmp1.z < -0.5)
{
//法向量为0,0,-1,上方
*nResult = XMVectorSetBinaryConstant(0, 0, -1, 0);
}
else if (tmp1.z > 0.5)
{
//法向量为0,0,1,下方
*nResult = XMVectorSetBinaryConstant(0, 0, 1, 0);
}
return true;
//return result;
}
else
{
return false;
}
//上面成功的进行了判断,可以得出grid编号了,不过还要算一下相交面(
return false;
}
Vector& Vector::clamp(const Vector& min, const Vector& max)
{
m_vector = XMVectorClamp(m_vector, min.getXMVector(), max.getXMVector());
return *this;
}