transform

P_camera.x = dot(P - eye, right)
P_camera.y = dot(P - eye, up)
P_camera.z = dot(P - eye, forward)

// 展开矩阵形式：
[ P_camera.x ] [ right.x right.y right.z -dot(eye, right) ] [ x ]
[ P_camera.y ] = [ up.x up.y up.z -dot(eye, up) ] [ y ]
[ P_camera.z ] [ forward.x forward.y forward.z -dot(eye, forward) ] [ z ]
[ 1 ] [ 0 0 0 1 ] [ 1 ]

直接构建：世界→相机 的变换矩阵
// 称为 View Matrix 或 Camera Matrix

上面那个矩阵就是viewMatrix