我有一个代码(游戏),在正射投影中有固定的相机。它运行平稳,直到我将相机位置从(0,0,1)
更改为(0,0,-1)
。
简而言之,我有2个纹理:
{ //texture 1
960.0f, 0.0f, -5.0f, 0.0f, 0.0f,
960.0f, 1080.0f, -5.0f, 1.0f, 0.0f,
1920.0f, 0.0f, -5.0f, 0.0f, 1.0f,
1920.0f, 1080.0f, -5.0f, 1.0f, 1.0f
}
{ // texture 2
1290.0f, 390.0f, -7.0f, 0.0f, 0.0f,
1290.0f, 690.0f, -7.0f, 1.0f, 0.0f,
1590.0f, 390.0f, -7.0f, 0.0f, 1.0f,
1590.0f, 690.0f, -7.0f, 1.0f, 1.0f
}
转换矩阵:
view = glm::lookAt
(
glm::vec3( 0.0f, 0.0f, 1.0f ),
glm::vec3( 0.0f, 0.0f, 0.0f ),
glm::vec3( 0.0f, 1.0f, 0.0f )
);
projection = glm::ortho
(
0.0f,
1920.0f,
0.0f,
1080.0f,
1.0f, // zNear
10.0f // zFar
);
顶点着色器:
#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, 1.0 );
TexCoord = vec2( aTexCoord.x, aTexCoord.y );
}
如果我运行此代码,它会正确显示两种纹理,进行深度测试,......
但是,如果我将相机位置更改为(0, 0, -1)
并将纹理的Z坐标更改为其反+5
和+7
,并保持相同方向(0, 0, 0)
,则不会显示(渲染)纹理。它不应该显示与更改前相同的内容吗?
该问题与正交投影矩阵有关,因为它不是居中的。当视图的z轴反转时,x轴也反转。注意Right-hand rule必须仍然满足,x.axis是y轴和z轴的叉积。
当几何图形位于z-5
and时,视图和投影矩阵如下所示
view = glm::lookAt( glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f); projection = glm::ortho(0.0f, 1920.0f, 0.0f, 1080.0f, 1.0f, 10.0f);
然后将对象投影到视口:
但是,如果切换几何体和视图的z位置,则会出现以下情况:
view = glm::lookAt( glm::vec3(0.0f, 0.0f, -1.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f);
然后该对象位于视口旁边:
沿X轴移动正交投影,以解决您的问题:
projection = glm::ortho(-1920.0f, 0.0f, 0.0f, 1080.0f, 1.0f, 10.0f);