我目前正在学习3D计算机图形学,并将平行投影规范化为Canocial视图体积(LookAt Matrix为熟悉的名称)。我尝试使用下面的纯JavaScript作为参数将其实现为代码。
var VRP = new Vertex(0,0,0);
var VPN = new Vertex(0,0,1);
var VUP = new Vertex(0,1,0);
var PRP = new Vertex(8,8,100);
var Window = [-1,17,-1,17];
var F = 1, B = -1;
现在,这是我的尝试。我首先将其转换为Canocial View体积。[注意:您可以直接将这些步骤跳过至代码here,并帮助我修复代码以将多维数据集向前移动到摄像机(屏幕)而不是移开
1。将VRP转换为来源
var TVRP = [];
TVRP[0] = [1, 0, 0, -VRP.x];
TVRP[1] = [0, 1, 0, -VRP.y];
TVRP[2] = [0, 0, 1, -VRP.z];
TVRP[3] = [0, 0, 0, 1];
2。旋转VRC,以使n轴,u轴和v轴与z轴,x轴和y轴依次对齐
function normalizeViewPlane(VPN) {
var unitVector = calculateUnitVector(VPN); //VPN/|VPN|
return normalizeVector(VPN,unitVector);
}
function normalizeViewUp(VUP, n) {
var dtProd = dotProduct(n,VUP);
var nVUP = new Vertex(n.x*dtProd, n.y*dtProd, n.z*dtProd);
VUP = new Vertex(VUP.x-nVUP.x, VUP.y-nVUP.y, VUP.z-nVUP.z);
var unitVector = calculateUnitVector(VUP); //VUP/|VUP|
return normalizeVector(VUP,unitVector);
}
function normalizeUVN(n,u) {
var V = crossProduct(n,u);
var unitVector = calculateUnitVector(V); //V/|V|
return normalizeVector(V,unitVector);
}
var n = normalizeViewPlane(VPN);
var v = normalizeViewUp(VUP, n);
var u = normalizeUVN(v, n);
var RVRC = [];
RVRC[0] = [u.x, u.y, u.z, 0];
RVRC[1] = [v.x, v.y, v.z, 0];
RVRC[2] = [n.x, n.y, n.z, 0];
RVRC[3] = [0, 0, 0, 1];
//Perform matrix multiplication 4x4 R.T(-VRP)
var res = multiplyMatrix4x4(RVRC, TVRP);
3。剪切DOP变得平行于z轴
function shearDOP(PRP, uMaxMin, vMaxMin) {
var CW = new Vertex(uMaxMin,vMaxMin,0);
var mPRP = new Vertex(PRP.x,PRP.y,PRP.z);
return new Vertex(CW.x - mPRP.x, CW.y - mPRP.y, CW.z - mPRP.z);
}
var uMaxMin = (Window[1]+Window[0])/2;
var vMaxMin = (Window[3]+Window[2])/2;
var DOP = shearDOP(PRP,uMaxMin,vMaxMin);
var HX = (DOP.x/DOP.z)*-1;
var HY = (DOP.y/DOP.z)*-1;
var Hpar = [];
Hpar[0] = [1,0,HX,0];
Hpar[1] = [0,1,HY,0];
Hpar[2] = [0,0,1,0];
Hpar[3] = [0,0,0,1];
//res = R.T(-VRP)
res = multiplyMatrix4x4(Hpar,res);
4。转换到视图体积原点的前面中心var Tpar = [];
Tpar[0] = [1,0,0,-uMaxMin];
Tpar[1] = [0,1,0,-vMaxMin];
Tpar[2] = [0,0,1,-F];
Tpar[3] = [0,0,0,1];
//res=Hpar.R.T(-VRP)
res = multiplyMatrix4x4(Tpar,res);
5。缩放以使视图体积受到平面的限制
var uMaxMin2 = 2/(Window[1]-Window[0]); var vMaxMin2 = 2/(Window[3]-Window[2]); var Spar = []; Spar[0] = [uMaxMin2, 0, 0, 0]; Spar[1] = [0, vMaxMin2, 0, 0]; Spar[2] = [0, 0, 1 / (F - B), 0]; Spar[3] = [0, 0, 0, 1]; //res=Tpar.Hpar.R.T(-VRP) res = multiplyMatrix4x4(Spar, res);
在将其转换为Canocial视图体积之后,我决定将多维数据集顶点乘以该最终结果转换矩阵。
//res=Spar.Tpar.Hpar.R.T(-VRP) p = multiplyMatrix1x4(res,p); //M is the parameter of cube vertice M.x = p[0]; M.y = p[1]; M.z = p[2];
因此,我的立方体正从摄像机移开,如下图所示。
但是,我希望立方体移动到离摄像机最近的位置,而不是移开,如下图所示(对象是房子)
我是否错过了步骤或误解了转换为Canocial View的算法?我将修改哪个函数或变量以使立方体像上面的房子一样?JSFiddle:https://jsfiddle.net/Marfin/hL2bmvz5/20/参考:https://telin.ugent.be/~sanja/ComputerGraphics/L06_Viewing_Part2_6pp.pdf
我目前正在学习3D计算机图形学,并将平行投影规范化为Canocial视图体积(LookAt Matrix为熟悉的名称)。我尝试使用纯JavaScript将其实现为代码...
[通常,如果您的凸轮正看着盒子,并且您希望凸轮朝盒子移动,请在凸轮和盒子之间获取矢量,然后将凸轮朝这个方向移动:
cam += (box-cam)