如何在现代 openGL 中绘制带有 3D 点的多边形？

Question

我知道在 2.0- openGL 中我们可以像这样简单地画一条线。

glBegin(GL_LINES);  
glVertex3f(20.0f,150.0f,0.0f);  
glVertex3f(220.0f,150.0f,0.0f);  
glVertex3f(200.0f,160.0f,0.0f);  
glVertex3f(200.0f,160.0f,0.0f);  
glEnd();

但是如何在现代 openGL(3.0+) 中做类似的事情

我看过Drawing round points using modern OpenGL但是答案不是关于某个点的，因为我想用具有特定坐标的点绘制多边形，这不是很有帮助。

我使用了这段代码，但它除了蓝色之外什么也没有显示background.what我错过了吗？

GLuint VertexArrayID;
    glGenVertexArrays(1, &VertexArrayID);
    glBindVertexArray(VertexArrayID);

static const GLfloat g_vertex_buffer_data[] = {
        20.0f, 150.0f, 0.0f, 1.0f,
            220.0f, 150.0f, 0.0f, 1.0f,
            200.0f, 160.0f, 0.0f, 1.0f
    };

GLuint vertexbuffer;
glGenBuffers(1, &vertexbuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);

do{

    // Clear the screen
    glClear( GL_COLOR_BUFFER_BIT );

    // 1rst attribute buffer : vertices
    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
    glVertexAttribPointer(
        0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
        4,                  // size
        GL_FLOAT,           // type
        GL_FALSE,           // normalized?
        0,                  // stride
        (void*)0            // array buffer offset
    );

    // Draw the triangle !
    glDrawArrays(GL_LINES, 0, 2); // 3 indices starting at 0 -> 1 triangle

    glDisableVertexAttribArray(0);

    // Swap buffers
    glfwSwapBuffers(window);


} // Check if the ESC key was pressed or the window was closed
while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
       glfwWindowShouldClose(window) == 0 );

Answer 1

1) 您必须定义一个顶点数组，其中包含多边形线的点。就像你的例子：

GLfloat vertices[] =
{
    20.0f, 150.0f, 0.0f, 1.0f,
    220.0f, 150.0f, 0.0f, 1.0f,
    200.0f, 160.0f, 0.0f, 1.0f
};

2) 您必须定义并绑定一个顶点缓冲区对象 (VBO) 才能将您的 vertices 传递给顶点着色器。像这样：

// This is the identifier for your vertex buffer
GLuint vbo;
// This creates our identifier and puts it in vbo
glGenBuffers(1, &vbo);
// This binds our vbo
glBindBuffer(GL_ARRAY_BUFFER, vbo);
// This hands the vertices into the vbo and to the rendering pipeline    
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

3) 现在我们准备画画了。这样做：

// "Enable a port" to the shader pipeline
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
// pass information about how vertex array is composed
glVertexAttribPointer(0, // same as in glEnableVertexAttribArray(0)
                      4, // # of coordinates that build a vertex
                      GL_FLOAT, // data type
                      GL_FALSE, // normalized?
                      0,        // stride
                      (void*)0);// vbo offset

glDrawArrays(GL_LINES, 0, 2);
glDisableVertexAttribArray(0);

步骤1)和2)可以在渲染之前完成作为初始化。步骤 3) 在您的渲染循环中完成。此外，您还需要一个顶点着色器和一个片段着色器来可视化带有颜色的线条。

如果您对这些事情一无所知并且想从 OpenGL 3 开始，我建议您从这样的教程重新开始： http://www.opengl-tutorial.org/beginners-tutorials/tutorial-1-opening-a-window/

如何在现代 openGL 中绘制带有 3D 点的多边形？

How to draw polygon with 3D points in modern openGL?

c++

opengl

opengl-3