使用 VAO 在 OpenGL 中更改绘制的实例化顺序
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【中文标题】使用 VAO 在 OpenGL 中更改绘制的实例化顺序【英文标题】：Instantiation order changing draw in OpenGL using VAO 【发布时间】：2015-04-20 19:25:28 【问题描述】：我尝试使用 VAO、VBO 和 IBO 在平面上绘制一堆球体。在使用这些之前，一切都按预期绘制。在我开始使用这些之后，事情变得很奇怪。我不能在这里发布我的整个代码，因为我有 5 个类（但如有必要，我可以提供指向我的代码的链接），所以我会尝试发布我认为有用的内容。
通过这个类我可以画一个球体：
SphereShaderProgram::SphereShaderProgram(std::string vertexShaderPath, std::string fragmentShaderPath) : ProgramManager(vertexShaderPath, fragmentShaderPath)
_sphereH = 20;
_sphereW = 20;
_vbo = 0;
_vao = 0;
_ibo = 0;
CreateProgram();
BuildSphere();
BuildVAO();
SphereShaderProgram::~SphereShaderProgram()
glDeleteVertexArrays(1, &_vao);
glDeleteBuffers(1, &_vbo);
glDeleteBuffers(1, &_ibo);
void SphereShaderProgram::DrawSphere(const glm::mat4 &Projection, const glm::mat4 &ModelView)
_ModelViewProjection = Projection * ModelView;
_ModelView = ModelView;
Bind(); //glUseProgram
glBindVertexArray(_vao);
LoadVariables();
glDrawElements(GL_TRIANGLES, _sphereIndexes.size(), GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
UnBind();
int SphereShaderProgram::Get1DIndex(int line, int column)
return line * (int) _sphereH + column;
void SphereShaderProgram::BuildSphere()
for (int l = 0; l < _sphereH - 1; l++)
for (int c = 0; c < _sphereW - 1; c++)
int v1_1 = Get1DIndex(l, c);
int v2_1 = Get1DIndex(l + 1, c + 1);
int v3_1 = Get1DIndex(l + 1, c);
int v1_2 = Get1DIndex(l, c);
int v2_2 = Get1DIndex(l, c + 1);
int v3_2 = Get1DIndex(l + 1, c + 1);
_sphereIndexes.push_back(v1_1);
_sphereIndexes.push_back(v2_1);
_sphereIndexes.push_back(v3_1);
_sphereIndexes.push_back(v1_2);
_sphereIndexes.push_back(v2_2);
_sphereIndexes.push_back(v3_2);
for (int l = 0; l < _sphereH; l++)
for (int c = 0; c < _sphereW; c++)
float theta = ((float) l / (_sphereH - 1)) * (float) PI;
float phi = ((float) c / (_sphereW - 1)) * 2 * (float) PI;
float x = sin(theta) * cos(phi);
float z = sin(theta) * sin(phi);
float y = cos(theta);
_sphereCoordinates.push_back(x);
_sphereCoordinates.push_back(y);
_sphereCoordinates.push_back(z);
void SphereShaderProgram::BuildVAO()
// Generate and bind the vertex array object
glGenVertexArrays(1, &_vao);
glBindVertexArray(_vao);
// Generate and bind the vertex buffer object
glGenBuffers(1, &_vbo);
glBindBuffer(GL_ARRAY_BUFFER, _vbo);
glBufferData(GL_ARRAY_BUFFER, _sphereCoordinates.size() * sizeof(float), &_sphereCoordinates[0], GL_STATIC_DRAW);
// Generate and bind the index buffer object
glGenBuffers(1, &_ibo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _ibo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, _sphereIndexes.size() * sizeof(unsigned int), &_sphereIndexes[0], GL_STATIC_DRAW);
glBindVertexArray(0);
void SphereShaderProgram::LoadUniformVariables()
glm::mat4 MVP = _ModelViewProjection;
glm::mat4 MV = _ModelView;
glm::mat3 N = glm::transpose(glm::inverse(glm::mat3(MV)));
glm::vec4 AC = glm::vec4(0.2, 0.2, 0.2, 1.0);
glm::vec4 DC = glm::vec4(0.7, 0.0, 0.0, 1.0);
glm::vec4 SC = glm::vec4(0.1, 0.1, 0.1, 1.0);
glm::vec3 LP = glm::vec3(1.0, 6.0, 4.0);
// OpenGL Matrices
GLuint ModelViewProjection_location = glGetUniformLocation(GetProgramID(), "mvpMatrix");
glUniformMatrix4fv(ModelViewProjection_location, 1, GL_FALSE, glm::value_ptr(MVP));
GLuint ModelView_location = glGetUniformLocation(GetProgramID(), "mvMatrix");
glUniformMatrix4fv(ModelView_location, 1, GL_FALSE, glm::value_ptr(MV));
GLuint Normal_location = glGetUniformLocation(GetProgramID(), "normalMatrix");
glUniformMatrix3fv(Normal_location, 1, GL_FALSE, glm::value_ptr(N));
// Lighting
GLuint AmbientColor_location = glGetUniformLocation(GetProgramID(), "ambientColor");
glUniform4fv(AmbientColor_location, 1, glm::value_ptr(AC));
GLuint DiffuseColor_location = glGetUniformLocation(GetProgramID(), "diffuseColor");
glUniform4fv(DiffuseColor_location, 1, glm::value_ptr(DC));
GLuint SpecularColor_location = glGetUniformLocation(GetProgramID(), "specularColor");
glUniform4fv(SpecularColor_location, 1, glm::value_ptr(SC));
GLuint LightPosition_location = glGetUniformLocation(GetProgramID(), "vLightPosition");
glUniform3fv(LightPosition_location, 1, glm::value_ptr(LP));
void SphereShaderProgram::LoadAtributeVariables()
// Vertex Attributes
GLuint VertexPosition_location = glGetAttribLocation(GetProgramID(), "vPosition");
glEnableVertexAttribArray(VertexPosition_location);
glVertexAttribPointer(VertexPosition_location, 3, GL_FLOAT, GL_FALSE, 0, 0);
void SphereShaderProgram::LoadVariables()
LoadUniformVariables();
LoadAtributeVariables();
还有一架飞机：
PlaneShaderProgram::PlaneShaderProgram(std::string vertexShaderPath, std::string fragmentShaderPath) : ProgramManager(vertexShaderPath, fragmentShaderPath)
CreateProgram();
_vbo = 0;
_vao = 0;
_ibo = 0;
BuildPlane();
BuildVAO();
PlaneShaderProgram::~PlaneShaderProgram()
glDeleteVertexArrays(1, &_vao);
glDeleteBuffers(1, &_vbo);
glDeleteBuffers(1, &_ibo);
void PlaneShaderProgram::DrawPlane(const glm::mat4 &Projection, const glm::mat4 &ModelView)
_ModelViewProjection = Projection * ModelView;
_ModelView = ModelView;
Bind();
glBindVertexArray(_vao);
LoadVariables();
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
UnBind();
void PlaneShaderProgram::BuildPlane()
_coordinates[0] = -1.0f;
_coordinates[1] = 0.0f;
_coordinates[2] = -1.0f;
_coordinates[3] = -1.0f;
_coordinates[4] = 0.0f;
_coordinates[5] = 1.0f;
_coordinates[6] = 1.0f;
_coordinates[7] = 0.0f;
_coordinates[8] = 1.0f;
_coordinates[9] = 1.0f;
_coordinates[10] = 0.0f;
_coordinates[11] = -1.0f;
_indexes[0] = 0;
_indexes[1] = 1;
_indexes[2] = 2;
_indexes[3] = 0;
_indexes[4] = 2;
_indexes[5] = 3;
void PlaneShaderProgram::BuildVAO()
// Generate and bind the vertex array object
glGenVertexArrays(1, &_vao);
glBindVertexArray(_vao);
// Generate and bind the vertex buffer object
glGenBuffers(1, &_vbo);
glBindBuffer(GL_ARRAY_BUFFER, _vbo);
glBufferData(GL_ARRAY_BUFFER, 12 * sizeof(GLfloat), _coordinates, GL_STATIC_DRAW);
// Generate and bind the index buffer object
glGenBuffers(1, &_ibo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _ibo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(GLuint), _indexes, GL_STATIC_DRAW);
glBindVertexArray(0);
void PlaneShaderProgram::LoadUniformVariables()
// OpenGL Matrices
GLuint ModelViewProjection_location = glGetUniformLocation(GetProgramID(), "mvpMatrix");
glUniformMatrix4fv(ModelViewProjection_location, 1, GL_FALSE, glm::value_ptr(_ModelViewProjection));
void PlaneShaderProgram::LoadAtributeVariables()
// Vertex Attributes
GLuint VertexPosition_location = glGetAttribLocation(GetProgramID(), "vPosition");
glEnableVertexAttribArray(VertexPosition_location);
glVertexAttribPointer(VertexPosition_location, 3, GL_FLOAT, GL_FALSE, 0, 0);
void PlaneShaderProgram::LoadVariables()
LoadUniformVariables();
LoadAtributeVariables();
另一方面，这是我的主要内容：
int main(void)
// Set the error callback
glfwSetErrorCallback(ErrorCallback);
// Initialize GLFW
if (!glfwInit())
printf("Error initializing GLFW!\n");
exit(EXIT_FAILURE);
// Set the GLFW window creation hints - these are optional
glfwWindowHint(GLFW_SAMPLES, 4);
// Create a window and create its OpenGL context
GLFWwindow* window = glfwCreateWindow(width, height, "OpenGL 4 Base", NULL, NULL);
// If the window couldn't be created
if (!window)
fprintf(stderr, "Failed to open GLFW window.\n");
glfwTerminate();
exit(EXIT_FAILURE);
// Sets the context of the specified window on the calling thread
glfwMakeContextCurrent(window);
// Initialize GLEW
glewExperimental = true;
GLenum glewError = glewInit();
if (glewError != GLEW_OK)
printf("Error initializing GLEW! %s\n", glewGetErrorString(glewError));
glfwDestroyWindow(window);
glfwTerminate();
exit(EXIT_FAILURE);
glfwSetKeyCallback(window, KeyCallback);
glfwSetWindowSizeCallback(window, WindowSizeCallback);
glfwSetScrollCallback(window, ScrollCallback);
// Set the view matrix
glm::mat4 ModelView = glm::lookAt(glm::vec3(0.0f, 7.0f, 15.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
// Init matrix stack
glm_ModelViewMatrix.push(ModelView);
PlaneShaderProgram PlaneShaderProgram("FloorVertexShader.txt", "FloorFragShader.txt");
SphereShaderProgram SphereShaderProgram("ADSPerVertexVertexShader.txt", "ADSPerVertexFragShader.txt");
//SphereShaderProgram SphereShaderProgram = SphereShaderProgram("ADSPerPixelVertexShader.txt", "ADSPerPixelFragShader.txt");
// Set a background color
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
// 3D objects
glEnable(GL_DEPTH_TEST);
float d = 2.0f;
float p0 = -10.0f + d / 2;
// Main Loop
while (!glfwWindowShouldClose(window))
// Clear color buffer
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Clone current modelview matrix, which can now be modified
glm_ModelViewMatrix.push(glm_ModelViewMatrix.top());
//------- ModelView Transformations
// Zoom in/out
glm_ModelViewMatrix.top() = glm::translate(glm_ModelViewMatrix.top(), glm::vec3(0.0, 0.0, zoom));
// Rotation
glm_ModelViewMatrix.top() = glm::rotate(glm_ModelViewMatrix.top(), beta, glm::vec3(1.0, 0.0, 0.0));
glm_ModelViewMatrix.top() = glm::rotate(glm_ModelViewMatrix.top(), alpha, glm::vec3(0.0, 0.0, 1.0));
//------- Draw the plane
glm_ModelViewMatrix.push(glm_ModelViewMatrix.top());
glm_ModelViewMatrix.top() = glm::scale(glm_ModelViewMatrix.top(), glm::vec3(7.0f, 1.0f, 7.0f));
PlaneShaderProgram.DrawPlane(Projection, glm_ModelViewMatrix.top());
glm_ModelViewMatrix.pop();
//------- Draw spheres
for (int i = 0; i < 10; i++)
for (int j = 0; j < 10; j++)
glm_ModelViewMatrix.push(glm_ModelViewMatrix.top());
glm_ModelViewMatrix.top() = glm::scale(glm_ModelViewMatrix.top(), glm::vec3(0.5f, 0.5f, 0.5f));
glm_ModelViewMatrix.top() = glm::translate(glm_ModelViewMatrix.top(), glm::vec3(p0 + i * d, 1.0f, p0 + j * d));
SphereShaderProgram.DrawSphere(Projection, glm_ModelViewMatrix.top());
glm_ModelViewMatrix.pop();
glm_ModelViewMatrix.pop();
// Swap buffers
glfwSwapBuffers(window);
// Get and organize events, like keyboard and mouse input, window resizing, etc...
glfwPollEvents();
// Close OpenGL window and terminate GLFW
glfwDestroyWindow(window);
// Finalize and clean up GLFW
glfwTerminate();
exit(EXIT_SUCCESS);
实例化平面然后是球体程序，我得到以下结果（根本没有平面）：
改变顺序，就是结果：
我正试图找出我所缺少的线索，因为我不知道哪里出了问题。在使用 VAO 之前（仅使用 glVertexAttribPointer 和 glDrawElements），一切都已正确绘制。
提前谢谢你。
【问题讨论】：
绘制时不要在每一帧都调用 LoadAtributeVariables 函数，而应该在 BuildVAO 函数中调用一次，因为 VAO 存储属性绑定。 当我这样做时，什么都没有画出来，@user3256930。 那么您可能还缺少其他东西。 VAO 的基本思想是它们存储属性绑定，因此您不必每次绘制时都调用它。本教程展示了如何正确设置它们并使用它们进行绘制：swiftless.com/tutorials/opengl4/4-opengl-4-vao.html。 【参考方案1】：问题在于glVertexAttribPointer() 调用的位置。您在 LoadAtributeVariables() 方法中调用它，而该方法又从 Draw*() 方法中调用。
这应该是 VAO 设置的一部分，原因如下：
在每次重绘时调用是低效的。此调用设置作为 VAO 状态一部分的状态。这就是首先使用 VAO 的全部想法。您可以在设置过程中将所有这些状态设置一次，然后只需要在绘制调用之前再次绑定 VAO，即可通过一次调用再次设置所有状态。 在您的情况下，VBO 在您拨打电话时未绑定。glVertexAttribPointer() 设置属性以从当前绑定的 VBO 中提取数据，即绑定为GL_ARRAY_BUFFER 的缓冲区。
第一个问题只是性能问题。第二个是您的代码不起作用的原因，因为在调用 glVertexAttribPointer() 时您没有正确的 VBO 绑定。
要解决此问题，您只需将LoadAtributeVariables() 调用移动到BuildVAO()，在此位置：
// Generate and bind the vertex buffer object
glGenBuffers(1, &_vbo);
glBindBuffer(GL_ARRAY_BUFFER, _vbo);
glBufferData(GL_ARRAY_BUFFER, _sphereCoordinates.size() * sizeof(float), &_sphereCoordinates[0], GL_STATIC_DRAW);
LoadAtributeVariables();
并将其从当前位置移除，以便在每次绘制调用之前不再调用它。
【讨论】：
嗨，@Reto。我做了你说的修改，现在我的绘图调用只包含 VAO 绑定、LoadUniformVariables 和 drawElements。但是，这导致程序崩溃。 :S 我错过了你说的话吗？ 为了让它工作，我必须在 draw call 中进行 VBO 和 IBO 绑定（我已经评论过它）。对吗？ 不，如果VAO的初始设置正确完成，您只需在draw call中绑定VAO。以上是关于使用 VAO 在 OpenGL 中更改绘制的实例化顺序的主要内容，如果未能解决你的问题，请参考以下文章
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