OpenGL - 阴影 map/Depth 地图给出奇怪的结果
OpenGL - Shadow map/Depth Map giving weird result
我正在尝试渲染我的深度图，现在我已经将它渲染到场景中的对象上以大致了解我得到的结果。据我了解，黑色值是靠近光线的物体，而白色距离较远。如果我弄错了，请纠正我。这是我得到的结果：Shadow map rendered onto a cube
根据这个结果，我推测我以错误的方式创建了帧缓冲区。这就是我生成它的方式：
void createFrameBuffer()
{
glGenFramebuffers(1, &frameBuffer);
glGenTextures(1, &DepthMap);
glBindTexture(GL_TEXTURE_2D, DepthMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT,
SHADOW_WIDTH, SHADOW_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
GL_TEXTURE_2D, DepthMap, 0);
glDrawBuffer(GL_NONE);
glReadBuffer(GL_NONE);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
我们已经按照 Learn OpenGL - Shadow Mapping 教程进行操作，我们的着色器看起来与他的几乎相同。所以那里应该没有任何问题。我想我误解了阴影映射的 CPU 部分，而不是 GPU.This 是我绘制所有内容、设置矩阵和使用程序的方式。
float orthoValue = 20.0f;
glm::mat4 lightProjection = glm::ortho(-orthoValue,
orthoValue, -orthoValue, orthoValue, NEARPLANE, FARPLANE);
glm::mat4 lightView = glm::lookAt(lightPos, glm::vec3(0.0f),
glm::vec3(0.0, 1.0f, 0.0));
glm::mat4 lightSpaceMatrix = lightProjection * lightView;
//lightSpaceMatrix[3] = glm::vec4(lightPos, 1.0f);
if (shadows == true) {
glUseProgram(sShaderProgram);
glBindVertexArray(mesh.VAO);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
glClear(GL_DEPTH_BUFFER_BIT);
glActiveTexture(GL_TEXTURE0);
glUniformMatrix4fv(glGetUniformLocation(sShaderProgram, "lightSpaceMatrix"),
1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
glUniformMatrix4fv(glGetUniformLocation(sShaderProgram, "modelMatrix"),
1, GL_FALSE, glm::value_ptr(mesh.modelMatrix));
glDrawArrays(GL_TRIANGLES, 0, mesh.vertices.size());
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glBindVertexArray(0);
setViewPort();
}
非常感谢提前提供的所有提示和帮助。如果我遗漏了重要信息，我会添加缺少的内容。
渲染部分的更多代码编辑，也编辑了我们绘制的方式：
这是主循环
glClearColor(0.0, 0.0, 0.5, 1);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDisable(GL_CULL_FACE);
glEnable(GL_LIGHTING);
//Keyboard input
keyPressed();
//Mouse movement
MousePointer();
lightProjection = glm::ortho(-orthoValue,
orthoValue, -orthoValue, orthoValue, NEARPLANE, FARPLANE);
glm::lookAt(lightPos, glm::vec3(0.0f),
glm::vec3(0.0, 1.0, 0.0));
lightSpaceMatrix = lightProjection * lightView;
glUseProgram(sShaderProgram);
glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
glClear(GL_DEPTH_BUFFER_BIT);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, DepthMap);
GLint samplerLoc = glGetUniformLocation(sShaderProgram, "DepthMap");
glUniform1i(samplerLoc, 0);
glUniformMatrix4fv(glGetUniformLocation(sShaderProgram, "lightSpaceMatrix"),
1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
for (int i = 0; i < objmesh.size(); i++) {
RenderShadows(*objmesh[i]);
}
glBindFramebuffer(GL_FRAMEBUFFER, 0);
setViewPort();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//glDisable(GL_DEPTH_TEST);
for (int i = 0; i < objmesh.size(); i++){
RenderVertices(gShaderProgram, *objmesh[i], true);
}
}
这里我们有使用shadow glsl程序的RenderShadows函数：
void RenderShadows(OBJMeshes mesh){
glUniformMatrix4fv(glGetUniformLocation(sShaderProgram, "modelMatrix"),
1, GL_FALSE, glm::value_ptr(mesh.modelMatrix));
glBindVertexArray(mesh.VAO);
glDrawArrays(GL_TRIANGLES, 0, mesh.vertices.size());
glBindVertexArray(0);
}
最后是渲染几何体的普通渲染函数：
void RenderVertices(GLuint shaderProgram, OBJMeshes mesh, bool shadows) {
GLuint CPUValuesID = glGetUniformLocation(gUbo, "MVP");
glBindBuffer(GL_UNIFORM_BUFFER, gUbo);
glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(CPUMatricies), &globalCPU);
glBindBuffer(GL_UNIFORM_BUFFER, mtlBuff);
glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(mtlValues), &mtl);
glUniformMatrix4fv(CPUValuesID, 1, GL_FALSE, &globalCPU.MVP[0][0]);
glUseProgram(shaderProgram);
glBindVertexArray(mesh.VAO);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, mesh.texture);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, DepthMap);
GLint samplerLoc = glGetUniformLocation(shaderProgram, "DepthMap");
glUniform1i(samplerLoc, 1);
glUniformMatrix4fv(glGetUniformLocation(shaderProgram, "modelMatrix"),
1, GL_FALSE, glm::value_ptr(mesh.modelMatrix));
glUniformMatrix4fv(glGetUniformLocation(shaderProgram, "lightSpaceMatrix"),
1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
glUniform3f(glGetUniformLocation(shaderProgram, "lightPos"), lightPos.x, lightPos.y, lightPos.z);
glDrawArrays(GL_TRIANGLES, 0, mesh.vertices.size());
glBindVertexArray(0);
}
如果你想将你的深度缓冲区渲染到一个纹理你必须绑定一个 GL_DEPTH_COMPONENT 格式的纹理到
帧缓冲缓冲区的渲染缓冲区。您所做的是将纹理绑定到帧缓冲区的颜色计划 0，因为您使用 GL_COLOR_ATTACHMENT0 在代码中绑定纹理。
glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, ColorMap0, 0 );
您需要做的是创建一个渲染缓冲区并将其绑定到您的帧缓冲区。
GLuint frameBuffer;
glGenFramebuffers(1, &frameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
GLuint renderbuffer;
glGenRenderbuffers( 1, &renderbuffer );
glBindRenderbuffer( GL_RENDERBUFFER, renderbuffer );
然后您必须使用 GL_DEPTH_ATTACHMENT:
将深度纹理绑定到帧缓冲区
glFramebufferTexture2D( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, DepthMap, 0 );
请注意，您可以将深度缓冲区和所有颜色平面的单独纹理绑定到帧缓冲区。
正确完成此操作后，您必须绘制场景并填充缓冲区 and/or 纹理。
// enable the depth test
glEnable( GL_DEPTH_TEST );
// bind frame buffer and clear the frame buffer and the depth buffer
glBindFramebuffer( GL_FRAMEBUFFER, frameBuffer );
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)`
// draw the scene
// ...
// unbind frame buffer
glBindFramebuffer( GL_FRAMEBUFFER, 0 );
// clear the drawing buffer and the depth buffer
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
帧缓冲区解除绑定后，您可以将其纹理用作阴影通道的输入。
要将纹理绑定到着色器，您必须将纹理绑定到纹理单元并将纹理单元的索引分配给着色器的统一采样器。
将纹理绑定到纹理单元：
GLuint DepthMap;
int textureUnit = 1;
glActiveTexture( GL_TEXTURE0 + textureUnit );
glBindTexture( GL_TEXTURE_2D, DepthMap );
使用程序并将纹理单元的索引分配给均匀采样器：
GLuint depthProg = ...;
glUseProgram( depthProg );
GLint depthSamplerLocation = glGetUniformLocation( u_depthAttachment );
glUniform1i( depthSamplerLocation, textureUnit );
答案的扩展
您的代码中还有一些问题：
在调用 RenderShadows 之前，在主循环中您清除了帧缓冲区 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);，但是在函数内部您绑定了一个帧缓冲区 glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);，因此清除是无用的。
在 RenderShadows 中，您尝试将 DepthMap 纹理绑定到纹理采样器，
但是 DepthMap 纹理是当前绑定帧缓冲区的目标纹理。纹理不能同时作为源和目标，这会导致未定义的行为。
在RenderVertices中，您必须将纹理单元的索引分配给
纹理采样器不是纹理对象：
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, DepthMap);
GLint samplerLoc = glGetUniformLocation(shaderProgram, "DepthMap");
// glUniform1i(samplerLoc, DepthMap); <- this is wrong
glUniform1i(samplerLoc, 1); // 1 because the texture is bound to GL_TEXTURE1
我正在尝试渲染我的深度图，现在我已经将它渲染到场景中的对象上以大致了解我得到的结果。据我了解，黑色值是靠近光线的物体，而白色距离较远。如果我弄错了，请纠正我。这是我得到的结果：Shadow map rendered onto a cube
根据这个结果，我推测我以错误的方式创建了帧缓冲区。这就是我生成它的方式：
void createFrameBuffer()
{
glGenFramebuffers(1, &frameBuffer);
glGenTextures(1, &DepthMap);
glBindTexture(GL_TEXTURE_2D, DepthMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT,
SHADOW_WIDTH, SHADOW_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
GL_TEXTURE_2D, DepthMap, 0);
glDrawBuffer(GL_NONE);
glReadBuffer(GL_NONE);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
我们已经按照 Learn OpenGL - Shadow Mapping 教程进行操作，我们的着色器看起来与他的几乎相同。所以那里应该没有任何问题。我想我误解了阴影映射的 CPU 部分，而不是 GPU.This 是我绘制所有内容、设置矩阵和使用程序的方式。
float orthoValue = 20.0f;
glm::mat4 lightProjection = glm::ortho(-orthoValue,
orthoValue, -orthoValue, orthoValue, NEARPLANE, FARPLANE);
glm::mat4 lightView = glm::lookAt(lightPos, glm::vec3(0.0f),
glm::vec3(0.0, 1.0f, 0.0));
glm::mat4 lightSpaceMatrix = lightProjection * lightView;
//lightSpaceMatrix[3] = glm::vec4(lightPos, 1.0f);
if (shadows == true) {
glUseProgram(sShaderProgram);
glBindVertexArray(mesh.VAO);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
glClear(GL_DEPTH_BUFFER_BIT);
glActiveTexture(GL_TEXTURE0);
glUniformMatrix4fv(glGetUniformLocation(sShaderProgram, "lightSpaceMatrix"),
1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
glUniformMatrix4fv(glGetUniformLocation(sShaderProgram, "modelMatrix"),
1, GL_FALSE, glm::value_ptr(mesh.modelMatrix));
glDrawArrays(GL_TRIANGLES, 0, mesh.vertices.size());
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glBindVertexArray(0);
setViewPort();
}
非常感谢提前提供的所有提示和帮助。如果我遗漏了重要信息，我会添加缺少的内容。
渲染部分的更多代码编辑，也编辑了我们绘制的方式：
这是主循环
glClearColor(0.0, 0.0, 0.5, 1);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDisable(GL_CULL_FACE);
glEnable(GL_LIGHTING);
//Keyboard input
keyPressed();
//Mouse movement
MousePointer();
lightProjection = glm::ortho(-orthoValue,
orthoValue, -orthoValue, orthoValue, NEARPLANE, FARPLANE);
glm::lookAt(lightPos, glm::vec3(0.0f),
glm::vec3(0.0, 1.0, 0.0));
lightSpaceMatrix = lightProjection * lightView;
glUseProgram(sShaderProgram);
glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
glClear(GL_DEPTH_BUFFER_BIT);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, DepthMap);
GLint samplerLoc = glGetUniformLocation(sShaderProgram, "DepthMap");
glUniform1i(samplerLoc, 0);
glUniformMatrix4fv(glGetUniformLocation(sShaderProgram, "lightSpaceMatrix"),
1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
for (int i = 0; i < objmesh.size(); i++) {
RenderShadows(*objmesh[i]);
}
glBindFramebuffer(GL_FRAMEBUFFER, 0);
setViewPort();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//glDisable(GL_DEPTH_TEST);
for (int i = 0; i < objmesh.size(); i++){
RenderVertices(gShaderProgram, *objmesh[i], true);
}
}
这里我们有使用shadow glsl程序的RenderShadows函数：
void RenderShadows(OBJMeshes mesh){
glUniformMatrix4fv(glGetUniformLocation(sShaderProgram, "modelMatrix"),
1, GL_FALSE, glm::value_ptr(mesh.modelMatrix));
glBindVertexArray(mesh.VAO);
glDrawArrays(GL_TRIANGLES, 0, mesh.vertices.size());
glBindVertexArray(0);
}
最后是渲染几何体的普通渲染函数：
void RenderVertices(GLuint shaderProgram, OBJMeshes mesh, bool shadows) {
GLuint CPUValuesID = glGetUniformLocation(gUbo, "MVP");
glBindBuffer(GL_UNIFORM_BUFFER, gUbo);
glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(CPUMatricies), &globalCPU);
glBindBuffer(GL_UNIFORM_BUFFER, mtlBuff);
glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(mtlValues), &mtl);
glUniformMatrix4fv(CPUValuesID, 1, GL_FALSE, &globalCPU.MVP[0][0]);
glUseProgram(shaderProgram);
glBindVertexArray(mesh.VAO);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, mesh.texture);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, DepthMap);
GLint samplerLoc = glGetUniformLocation(shaderProgram, "DepthMap");
glUniform1i(samplerLoc, 1);
glUniformMatrix4fv(glGetUniformLocation(shaderProgram, "modelMatrix"),
1, GL_FALSE, glm::value_ptr(mesh.modelMatrix));
glUniformMatrix4fv(glGetUniformLocation(shaderProgram, "lightSpaceMatrix"),
1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
glUniform3f(glGetUniformLocation(shaderProgram, "lightPos"), lightPos.x, lightPos.y, lightPos.z);
glDrawArrays(GL_TRIANGLES, 0, mesh.vertices.size());
glBindVertexArray(0);
}
如果你想将你的深度缓冲区渲染到一个纹理你必须绑定一个 GL_DEPTH_COMPONENT 格式的纹理到
帧缓冲缓冲区的渲染缓冲区。您所做的是将纹理绑定到帧缓冲区的颜色计划 0，因为您使用 GL_COLOR_ATTACHMENT0 在代码中绑定纹理。
glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, ColorMap0, 0 );
您需要做的是创建一个渲染缓冲区并将其绑定到您的帧缓冲区。
GLuint frameBuffer;
glGenFramebuffers(1, &frameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
GLuint renderbuffer;
glGenRenderbuffers( 1, &renderbuffer );
glBindRenderbuffer( GL_RENDERBUFFER, renderbuffer );
然后您必须使用 GL_DEPTH_ATTACHMENT:
glFramebufferTexture2D( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, DepthMap, 0 );
请注意，您可以将深度缓冲区和所有颜色平面的单独纹理绑定到帧缓冲区。
正确完成此操作后，您必须绘制场景并填充缓冲区 and/or 纹理。
// enable the depth test
glEnable( GL_DEPTH_TEST );
// bind frame buffer and clear the frame buffer and the depth buffer
glBindFramebuffer( GL_FRAMEBUFFER, frameBuffer );
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)`
// draw the scene
// ...
// unbind frame buffer
glBindFramebuffer( GL_FRAMEBUFFER, 0 );
// clear the drawing buffer and the depth buffer
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
帧缓冲区解除绑定后，您可以将其纹理用作阴影通道的输入。
要将纹理绑定到着色器，您必须将纹理绑定到纹理单元并将纹理单元的索引分配给着色器的统一采样器。
将纹理绑定到纹理单元：
GLuint DepthMap;
int textureUnit = 1;
glActiveTexture( GL_TEXTURE0 + textureUnit );
glBindTexture( GL_TEXTURE_2D, DepthMap );
使用程序并将纹理单元的索引分配给均匀采样器：
GLuint depthProg = ...;
glUseProgram( depthProg );
GLint depthSamplerLocation = glGetUniformLocation( u_depthAttachment );
glUniform1i( depthSamplerLocation, textureUnit );
答案的扩展
您的代码中还有一些问题：
在调用 RenderShadows 之前，在主循环中您清除了帧缓冲区 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);，但是在函数内部您绑定了一个帧缓冲区 glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);，因此清除是无用的。
在 RenderShadows 中，您尝试将 DepthMap 纹理绑定到纹理采样器，
但是 DepthMap 纹理是当前绑定帧缓冲区的目标纹理。纹理不能同时作为源和目标，这会导致未定义的行为。
在RenderVertices中，您必须将纹理单元的索引分配给
纹理采样器不是纹理对象：
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, DepthMap);
GLint samplerLoc = glGetUniformLocation(shaderProgram, "DepthMap");
// glUniform1i(samplerLoc, DepthMap); <- this is wrong
glUniform1i(samplerLoc, 1); // 1 because the texture is bound to GL_TEXTURE1