Question

我试图用IBO渲染两个不同的三角形。我将六个顶点存储在一个VBO中，并试图通过两个独立的IBO访问它们。问题是第一次IBO渲染，但第二次没有。初始化时会调用createVertices和createIndices。

    void createVertices()
    {
        //Vertex Data
    GLfloat v[] = { 0.95f, 0.75f, 0.0f, 1.0f,
                0.75f, -0.75f, 0.0f, 1.0f,
                0.0f, -0.75f, 0.0f, 1.0f,                  //END OF TRIANGLE 1 
            -0.75, 0.75f, 0.5f, 1.0f,
            -0.75, -0.75, 0.5f, 1.0f,
                0.0f, -0.75, 0.5f, 1.0f };                  //END OF TRIANGLE 2

        glGenVertexArrays(1, &VAO);
    glBindVertexArray(VAO);
        glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);

    glBufferData(GL_ARRAY_BUFFER, sizeof(v), v, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    }

//////////

    void createIndices()
    {

    GLushort i[] = { 0,1,2};


    glGenBuffers(2, IBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO[0]);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(i), i, GL_STATIC_DRAW);
    size = (sizeof(i)/sizeof(GLushort));   //USED IN DRAWELEMENTS


    GLushort w[] = { 3,4,5};

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO[1]);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(w), w, GL_STATIC_DRAW);
    size2 = (sizeof(i)/sizeof(GLushort));   //USED IN DRAWELEMENTS


    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    }

/////////

    void Render()
    {
    glClear(GL_COLOR_BUFFER_BIT);

    glUseProgram(shader.SProgram);           
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glVertexAttribPointer(0,4, GL_FLOAT, GL_FALSE, 0, 0);


    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO[0]);
    glDrawElements(GL_TRIANGLES,size,GL_UNSIGNED_SHORT,(GLvoid*)IBO[0]);

        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO[1]);
    glDrawElements(GL_TRIANGLES,size2,GL_UNSIGNED_SHORT,(GLvoid*)IBO[1]);

    glUseProgram(0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    }

Answer 1

这没有意义：

glDrawElements(GL_TRIANGLES,size,GL_UNSIGNED_SHORT,(GLvoid*)IBO[0]);
                                                   ^^^^^^^^^^^^^^

带有IBO绑定的glDrawElements参数是缓冲区的偏移量，就像gl ...指针和VBO一样。你可能只想要这个

glDrawElements(GL_TRIANGLES,size,GL_UNSIGNED_SHORT,(GLvoid*)0);

对于您的两个IBO，只需将IBO本身与

绑定

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO[…]);

如何在OpenGL中绑定来自一个VBO的多个IBO

1 个答案: