Some Matrix functions for 3d projection

matrisprojection.js

function matrix(m){
    return m || [
        [1,0,0,0],
        [0,1,0,0],
        [0,0,1,0],
        [0,0,0,1],
    ];
}

function projectionmatrix(fov,aspect,znear,zfar){
    let fovrad = 1/Math.tan((fov/2).toRadians());
    let m = matrix();
    m[0][0] = aspect*fovrad;
    m[1][1] = fovrad;
    m[2][2] = zfar / (zfar-znear);
    m[3][2] = (-zfar *znear)/(zfar-znear);
    m[2][3] = 1;
    m[3][3] = 0;
    return m;
}  

function vector4mat4x4mul(v, m){
    let x = v.x * m[0][0]+v.y*m[1][0]+v.z*m[2][0]+m[3][0];
    let y = v.x * m[0][1]+v.y*m[1][1]+v.z*m[2][1]+m[3][1];
    let z = v.x * m[0][2]+v.y*m[1][2]+v.z*m[2][2]+m[3][2];
    let w = v.x * m[0][3]+v.y*m[1][3]+v.z*m[2][3]+m[3][3];
    return vector(x,y,z,w);
}

function vector(x,y,z,w){
    return { x:x,y:y,z:z,w:w||1}; 
}

function normalizevector(v){
    let x = v.x/v.w; 
    let y = v.y/v.w;
    let z = v.z/v.w;
    return vector(x,y,z);
}

//Algorithm:
//triangle = [vA,vB,vC] 
//transformedTriangle = [normalizevector(vector4mat4x4mul(vA)),normalizevector(vector4mat4x4mul(vB)),normalizevector(vector4mat4x4mul(vC))]
//drawtriangle(triangle);