检索具有广告牌效果的正确相机对象坐标

Question

我正在使用OpenGL中的billboarding effect在世界空间上显示文本。

正常显示：

具有广告牌效果，文本四边形不会跟随红点。奇怪的是，当点沿x轴时，它的确跟随。我认为更改viewModel矩阵的前三列会扭曲相机对象的位置。

如何从viewModel矩阵中提取正确的四边形坐标？

//billboard code
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoord;

out vec2 TexCoord;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{   
    //gl_Position = projection * view  * model * vec4(aPos, 1.0f);

    mat4 mv = view*model; //viewModel matrix

    mv[0][0] = 1.0; 
    mv[0][1] = 0.0; 
    mv[0][2] = 0.0;

    mv[1][0] = 0.0; 
    mv[1][1] = 1.0; 
    mv[1][2] = 0.0;

    mv[2][0] = 0.0; 
    mv[2][1] = 0.0; 
    mv[2][2] = 1.0;

    //mv[3][0] = model[3][0]; 
    //mv[3][1] = model[3][1];
    //mv[3][2] = model[3][2];

    gl_Position = projection * mv * vec4(aPos, 1.0f);
    TexCoord = vec2(aTexCoord.x, aTexCoord.y);
}