OpenGL 在不同的 VBO 中绘制具有不同颜色、顶点位置和顶点颜色的点？

Question

我想用不同的颜色画不同的点。我把顶点位置数据和颜色数据放在不同的VBO中，如下图：

这是我的 C++ 代码：

    m_Points.push_back(glm::vec3(4, 0, 0));
    m_Points.push_back(glm::vec3(0, 2, 0));
    m_Points.push_back(glm::vec3(0, 0, 3));
    m_Points.push_back(glm::vec3(0, 0, 6));

    m_Colors.push_back(glm::vec3(0, 1.0, 0));
    m_Colors.push_back(glm::vec3(1.0, 0, 0));
    m_Colors.push_back(glm::vec3(0, 0, 1.0));
    m_Colors.push_back(glm::vec3(1.0, 1.0, 0));

    glEnable(GL_PROGRAM_POINT_SIZE);


    glGenVertexArrays(1, &m_VAO);
    glBindVertexArray(m_VAO);

    // the first VBO, it is the coordinates
    glGenBuffers(1, &m_VBO);
    glBindBuffer(GL_ARRAY_BUFFER, m_VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec3) * sizeof(m_Points), &m_Points[0][0], GL_DYNAMIC_DRAW);

    // the second VBO, the color
    glGenBuffers(1, &m_VBO_Color);
    glBindBuffer(GL_ARRAY_BUFFER, m_VBO_Color);
    glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec3) * sizeof(m_Colors), &m_Colors[0][0], GL_DYNAMIC_DRAW);

    glEnableVertexAttribArray(0);
    // in file axis.vs, there is a statement
    // layout (location = 0) in vec3 vertex;
    // the first argument 0 means (location = 0)
    glVertexAttribPointer(0,                 // location = 0 in vertics shader file
                          3,                 // the position has X,Y,Z 3 elements
                          GL_FLOAT,          // element type
                          GL_FALSE,          // do not normalize
                          sizeof(glm::vec3), // Stride
                          (void *) nullptr); // an offset of into the array, it is 0


    glEnableVertexAttribArray(1);
    // in file axis.vs, there is a statement
    // layout (location = 1) in vec3 vertex;
    // the first argument 1 means (location = 1)
    glVertexAttribPointer(1,                 // location = 1 in vertics shader file
                          3,                 // the position has R,G,B 3 elements
                          GL_FLOAT,          // element type
                          GL_FALSE,          // do not normalize
                          sizeof(glm::vec3), // Stride
                          (void *) nullptr); // an offset of into the array, it is 0


    glBindVertexArray(0);

m_Points 和 m_Colors 都是某种 std::vector<glm::vec3>

这是我的顶点着色器和帧着色器：

layout (location = 0) in vec3 vertex;
layout (location = 1) in vec3 color;

uniform mat4 projection;
uniform mat4 view;
uniform mat4 model;

out vec3 ObjectColor;

void main()
{
    gl_Position = projection * view * model * vec4(vertex, 1.0);
    gl_PointSize = 10.0;
    ObjectColor = color;

}

#version 330 core

in vec3 ObjectColor;

out vec4 FragColor;

void main()
{
    FragColor = vec4(ObjectColor, 1.0f);
}

绘制代码如下所示：

    shader.use();
    glBindVertexArray(m_VAO);
    glDrawArrays(GL_POINTS, 0, m_Points.size());

但是我想通过AddPoint()函数动态添加一些点，所以这里是在向量中添加顶点和颜色元素的代码：

void AddPoint() 
{
    glm::vec3 p(5.0, 6.0, 0.0);    
    m_Points.push_back(p);
    glBindBuffer(GL_ARRAY_BUFFER, m_VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec3) * m_Points.size(), &m_Points[0][0], GL_DYNAMIC_DRAW);

    glm::vec3 b(1.0, 0.0, 0.0);
    m_Colors.push_back(b);
    glBindBuffer(GL_ARRAY_BUFFER, m_VBO_Color);
    glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec3) * m_Colors.size(), &m_Colors[0][0], GL_DYNAMIC_DRAW);
}

问题是：最初的 4 个点以 4 种不同的颜色正确显示，但 AddPoint() 始终不起作用，我没有看到任何新添加和渲染的点。

我知道如果我把顶点位置放在一个VBO中，

如：

日期数组可以是：

x, y, z, r, g, b
x, y, z, r, g, b
x, y, z, r, g, b
x, y, z, r, g, b

它没有任何问题。

但是为什么把location和color放在不同的VBO里就不行了？

有什么想法吗？谢谢。

这个问题(c++ - Storing different vertex attributes in different VBO's - Stack Overflow)是相关的，但我仍然不知道为什么我的问题仍然出现。

编辑 Rabbid76 指出 glVertexAttribPointer() 函数仅通过 glBindBuffer 附加（复制）来自先前绑定 VBO 的数据。这表明我不能将顶点位置数组和顶点颜色数组放在不同的 VBO 中？

EDIT2 我的 AddPoint() 功能在这里错了吗？

Answer 1

glVertexAttribPointer associated the buffer object, which is bound to the GL_ARRAY_BUFFER target, to the specified attribute. The specification is stored in the state vector of the current Vertex Array Object.
调用 glBindBuffer, before glVertexAttribPointer 必须绑定正确的缓冲区对象：

// the first VBO, it is the coordinates
glGenBuffers(1, &m_VBO);
glBindBuffer(GL_ARRAY_BUFFER, m_VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec3) * sizeof(m_Points), &m_Points[0][0], GL_DYNAMIC_DRAW);

// the second VBO, the color
glGenBuffers(1, &m_VBO_Color);
glBindBuffer(GL_ARRAY_BUFFER, m_VBO_Color);
glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec3) * sizeof(m_Colors), &m_Colors[0][0], GL_DYNAMIC_DRAW);

glEnableVertexAttribArray(0);

glBindBuffer(GL_ARRAY_BUFFER, m_VBO); // <--- bind `m_VBO`

glVertexAttribPointer(0,                 // location = 0 in vertics shader file
                      3,                 // the position has X,Y,Z 3 elements
                      GL_FLOAT,          // element type
                      GL_FALSE,          // do not normalize
                      sizeof(glm::vec3), // Stride

glEnableVertexAttribArray(1);

glBindBuffer(GL_ARRAY_BUFFER, m_VBO_Color); // <--- bind `m_VBO_Color`

glVertexAttribPointer(1,                 // location = 1 in vertics shader file
                      3,                 // the position has R,G,B 3 elements
                      GL_FLOAT,          // element type
                      GL_FALSE,          // do not normalize
                      sizeof(glm::vec3), // Stride
                      (void *) nullptr); // an offset of into the array, it is 0

OpenGL 在不同的 VBO 中绘制具有不同颜色、顶点位置和顶点颜色的点？

OpenGL draw points with different colors, vertex location and vertex color in different VBOs?

c++

opengl

glsl

vbo

glm-math