我已经成功地从我的光源视角渲染了场景到深度立方图中,但我不太明白如何将其投影到我的场景上。
这里是当前情况的短片:http://youtu.be/54WXDWxqmXw
我在这里找到了一个实现示例:
这似乎很容易理解,因此我认为这是一个很好的入门方式,但我在矩阵方面遇到了一些困难(如上面的视频所示)。
我的顶点着色器:
#version 330 core
layout(std140) uniform ViewProjection
{
mat4 V;
mat4 P;
};
layout(location = 0) in vec3 vertexPosition;
layout(location = 1) in vec2 vertexUV;
out vec2 UV;
out vec4 posCs;
uniform mat4 M;
uniform mat4 lightView;
void main()
{
mat4 MVP = P *V *M;
gl_Position = MVP *vec4(vertexPosition,1);
UV = vertexUV;
posCs = V *M *vec4(vertexPosition,1);
}
片段着色器:
#version 330 core
in vec2 UV;
in vec4 posCs;
out vec4 color;
// Diffuse texture
uniform sampler2D renderTexture;
uniform samplerCubeShadow shadowCubeMap;
uniform mat4 lightView;
uniform mat4 lightProjection;
uniform mat4 camViewInv;
void main()
{
color = texture2D(renderTexture,UV).rgba;
mat4 lView = mat4(1); // The light is currently at the world origin, so we'll skip the transformation for now (The less potential error sources the better)
vec4 posLs = lView *camViewInv *posCs;
vec4 posAbs = abs(posLs);
float fs_z = -max(posAbs.x,max(posAbs.y,posAbs.z));
vec4 clip = lightProjection *vec4(0.0,0.0,fs_z,1.0);
float depth = (clip.z /clip.w) *0.5 +0.5;
vec4 r = shadowCube(shadowCubeMap,vec4(posLs.xyz,depth));
color *= r;
}
lightProjection是我用来将场景渲染到立方体贴图中的投影矩阵。
关于'camViewInv',我不是完全确定,但从我上面链接的示例中得出了以下结论:
glm::mat4 camViewInv(
camView[0][0],camView[1][0],camView[2][0],0.0f,
camView[0][1],camView[1][1],camView[2][1],0.0f,
camView[0][2],camView[1][2],camView[2][2],0.0f,
camPos[0],camPos[1],camPos[2],1.0f
);
camView是相机的视图矩阵,camPos是相机的世界空间位置。
我认为其他所有内容都应该是不言自明的。
我看不出着色器有什么问题,但我相当确定场景被正确地渲染到了立方体贴图中(如上面的视频所示)。也许比我更熟练的人可以发现问题。
// 更新:
关于创建/使用阴影立方体贴图的一些额外信息:
创建立方体贴图纹理:
unsigned int frameBuffer;
glGenFramebuffers(1,&frameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER,frameBuffer);
unsigned int texture;
glGenTextures(1,&texture);
glBindTexture(GL_TEXTURE_CUBE_MAP,texture);
glTexParameteri(GL_TEXTURE_CUBE_MAP,GL_TEXTURE_COMPARE_FUNC,GL_LEQUAL);
glTexParameteri(GL_TEXTURE_CUBE_MAP,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_CUBE_MAP,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_CUBE_MAP,GL_TEXTURE_WRAP_R,GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_CUBE_MAP,GL_TEXTURE_WRAP_S,GL_CLAMP_TO_BORDER);
glTexParameteri(GL_TEXTURE_CUBE_MAP,GL_TEXTURE_WRAP_T,GL_CLAMP_TO_BORDER);
glTexParameteri(GL_TEXTURE_CUBE_MAP,GL_TEXTURE_COMPARE_MODE,GL_COMPARE_R_TO_TEXTURE);
for(int i=0;i<6;i++)
{
glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X +i,0,GL_DEPTH_COMPONENT,size,size,0,GL_DEPTH_COMPONENT,GL_FLOAT,0);
glFramebufferTexture2D(GL_FRAMEBUFFER,GL_DEPTH_ATTACHMENT,GL_TEXTURE_CUBE_MAP_POSITIVE_X +i,texture,0);
glDrawBuffer(GL_NONE);
}
灯光矩阵:
glm::perspective<float>(90.f,1.f,2.f,m_distance); // Projection Matrix
// View Matrices
glm::vec3 pos = GetPosition(); // Light worldspace position
glm::lookAt(pos,pos +glm::vec3(1,0,0),glm::vec3(0,1,0));
glm::lookAt(pos,pos +glm::vec3(-1,0,0),glm::vec3(0,1,0));
glm::lookAt(pos,pos +glm::vec3(0,1,0),glm::vec3(0,0,-1))
glm::lookAt(pos,pos +glm::vec3(0,-1,0),glm::vec3(0,0,1))
glm::lookAt(pos,pos +glm::vec3(0,0,1),glm::vec3(0,1,0))
glm::lookAt(pos,pos +glm::vec3(0,0,-1),glm::vec3(0,1,0))
顶点着色器:
#version 330 core
layout(location = 0) in vec4 vertexPosition;
uniform mat4 shadowMVP;
void main()
{
gl_Position = shadowMVP *vertexPosition;
}
片段着色器:
#version 330 core
layout(location = 0) out float fragmentDepth;
void main()
{
fragmentdepth = gl_FragCoord.z;
}
GL_CLAMP_TO_BORDER
。默认的边框颜色是0.0(换句话说,它的行为就像深度缓冲区中有一个距离为0单位的东西),因此这可能解释了只有Z方向的光照起作用的异常行为。你应该对所有3个方向使用GL_CLAMP_TO_EDGE
。我明天会仔细看一下其余部分。 - Andon M. Coleman