Question

我正在尝试使用顶点数组对象在OpenGL 4.1中绘制一些顶点和索引：

float vertices[] = {-0.8, -0.8, 0, 0.8, -0.8, 0, 0, 0.8, 0};
unsigned int indices[] = { 0, 1, 2 };

设置VAO并使用glDrawElements（）绘制后，我得到一个空屏幕。我还尝试使用一对简单的着色器，只返回原始顶点位置和硬编码颜色，但也没有运气。

以下是设置VBO和VAO的代码：

unsigned int vertexArray;
glGenVertexArrays(1, &vertexArray);
glBindVertexArray(vertexArray);

unsigned int vertexBufferID;
unsigned int indexBufferID;

glGenBuffers(1, &vertexBufferID);
glGenBuffers(1, &indexBufferID);

glBindBuffer(GL_ARRAY_BUFFER, vertexBufferID);
glBufferData(GL_ARRAY_BUFFER, 4 * vertexCount, vertices, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 4 * vertexCount, 0);

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBufferID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 4 * indexCount, indices, GL_STATIC_DRAW);

我使用以下方式绘制VAO：

glBindVertexArray(vertexArray);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, (void*)0);

这是所有OpenGL调用的痕迹：

// Setup code

glViewport(0,0,1024,768)
glGetString(GL_RENDERER)="GeForce GT 540M/PCIe/SSE2" 
glGetString(GL_VENDOR)="NVIDIA Corporation" 
glGetString(GL_VERSION)="4.1.0 NVIDIA 359.46" 
glGetString(GL_SHADING_LANGUAGE_VERSION)="4.10 NVIDIA via Cg compil..." 
glEnable(GL_DEPTH_TEST)
glDepthFunc(GL_LESS)
glGenVertexArrays(1,000000000015F9B4)
glBindVertexArray(1)
glGenBuffers(1,000000000015F9D4)
glGenBuffers(1,000000000015F9F4)
glBindBuffer(GL_ARRAY_BUFFER,1)
glBufferData(GL_ARRAY_BUFFER,36,000000000015FA48,GL_STATIC_DRAW)
glEnableVertexAttribArray(0)
glVertexAttribPointer(0,3,GL_FLOAT,false,36,0000000000000000)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,2)
glBufferData(GL_ELEMENT_ARRAY_BUFFER,12,000000000015FA88,GL_STATIC_DRAW)
glClearColor(0.300000,0.300000,0.400000,1.000000)

// End of setup, here's the code rendering two frames (they just repeat):

glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT)
glBindVertexArray(1)
glDrawElements(GL_TRIANGLES,3,GL_UNSIGNED_INT,0000000000000000)
glGetError()=GL_NO_ERROR 
wglSwapBuffers(0000000069011A82)=true 

glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT)
glBindVertexArray(1)
glDrawElements(GL_TRIANGLES,3,GL_UNSIGNED_INT,0000000000000000)
glGetError()=GL_NO_ERROR 
wglSwapBuffers(0000000069011A82)=true

据我所知，我正在做的每个教程都说我应该做的事情，但出于某种原因，我的屏幕上什么都没有出现。我错过了什么？

Answer 1

您的数据紧密打包在数组中，因此glVertexAttribPointer中的stride参数应为0.顺便说一句，如果声明静态数组，则应使用sizeof来传递大小数组而不是依赖于实现的事物，如4 * vertexCount：

glBindBuffer(GL_ARRAY_BUFFER, vertexBufferID);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBufferID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

OpenGL 4.1：顶点数组对象什么都不绘制

1 个答案: