opengl中的旋转、平移、缩放矩阵生成函数

构建并返回平移矩阵

mat4 buildTranslate(float x, float y, float z)
{ mat4 trans = mat4(1.0, 0.0, 0.0, 0.0, 
                    0.0, 1.0, 0.0, 0.0, 
                    0.0, 0.0, 1.0, 0.0, 
                    x, y, z, 1.0 ); 
  return trans;
} 

构建并返回绕x轴的旋转矩阵

mat4 buildRotateX(float rad)
{ mat4 xrot = mat4(1.0, 0.0, 0.0, 0.0, 
                   0.0, cos(rad), -sin(rad), 0.0, 
                   0.0, sin(rad), cos(rad), 0.0, 
                   0.0, 0.0, 0.0, 1.0 ); 
  return xrot;
}

构建并返回绕y轴的旋转矩阵

mat4 buildRotateY(float rad)
{ mat4 yrot = mat4(cos(rad), 0.0, sin(rad), 0.0, 
                   0.0, 1.0, 0.0, 0.0, 
                   -sin(rad), 0.0, cos(rad), 0.0, 
                   0.0, 0.0, 0.0, 1.0 ); 
  return yrot;
}

构建并返回绕z轴的旋转矩阵

mat4 buildRotateZ(float rad)
{ mat4 zrot = mat4(cos(rad), -sin(rad), 0.0, 0.0, 
                   sin(rad), cos(rad), 0.0, 0.0, 
                   0.0, 0.0, 1.0, 0.0, 
                   0.0, 0.0, 0.0, 1.0 ); 
  return zrot;
}

构建并返回缩放矩阵

mat4 buildScale(float x, float y, float z)
{ mat4 scale = mat4(x, 0.0, 0.0, 0.0, 
                    0.0, y, 0.0, 0.0, 
                    0.0, 0.0, z, 0.0, 
                    0.0, 0.0, 0.0, 1.0 ); 
  return scale;
}

小结