渲染阴影的OpenGL正交投影问题

Question

我一直在尝试在 SFML 2.2 的 OpenGL 引擎中实现阴影映射，但它们似乎无法正确渲染。我相信我将问题缩小到用于计算阴影的正射投影。

/* before the main loop, creating the depth buffer for shadow mapping */
glm::vec3 lightPos(glm::vec3(-45.f, 45.f, -40.f));

const GLuint SHADOW_WIDTH = 1024, SHADOW_HEIGHT = 1024;
GLuint depthMapFBO;
glGenFramebuffers(1, &depthMapFBO);

GLuint depthMap;
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_CLAMP_TO_BORDER);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
GLfloat borderColor[] = { 1.0, 1.0, 1.0, 1.0 };
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);

glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthMap, 0);
glDrawBuffer(GL_NONE);
glReadBuffer(GL_NONE);
glBindFramebuffer(GL_FRAMEBUFFER, 0);

glClearColor(0.1f, 0.1f, 0.1f, 1.0f);

/* in the main loop, sending information to the appropiate shaders and setting viewports */
glm::mat4 lightProjection, lightView;
glm::mat4 lightSpaceMatrix;
GLfloat near_plane = 1.f, far_plane = 300.f;
lightProjection = glm::ortho(-10.f, 10.f, -10.f, 10.f, near_plane, far_plane);
lightView       = glm::lookAt(lightPos, glm::vec3(0.0f), glm::vec3(0.0, 1.0, 0.0));
lightSpaceMatrix = lightProjection * lightView;

glUseProgram(simpleDepthShader);
glUniformMatrix4fv(glGetUniformLocation(simpleDepthShader, "lightSpaceMat"), 1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
    glClear(GL_DEPTH_BUFFER_BIT);
    RenderScene();
glBindFramebuffer(GL_FRAMEBUFFER, 0);

// reset viewport, and display the scene as normal
glViewport(0, 0, window.getSize().x, window.getSize().y);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glUniform3fv(glGetUniformLocation(lightingShader, "lightPos_shade"), 1, &lightPos[0]);
glUniform3fv(glGetUniformLocation(lightingShader, "viewPos"), 1, &getPos()[0]);
glUniformMatrix4fv(glGetUniformLocation(lightingShader, "lightSpaceMat"), 1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, depthMap);

RenderScene();

我已将视图和投影矩阵应用于相机以查看光线所看到的内容，this was the result (along with the view from the depth buffer)。

这是场景的样子with the shadows（由于某种原因，摊位的阴影甚至没有投射到自己身上）。

Answer 1

您的着色器似乎没有正确获取您的阴影像素。

当您使用光照矩阵变换顶点时，它们在 [-1, 1] 范围内，但纹理采样在 [0, 1] 范围内。

http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-16-shadow-mapping/