Question

使用C ++和OpenGL我使用四边形，线条和点绘制了一个立方体。我现在正试图让我的代码更密集。为了达到这个目的，我想使用for循环。

我的立方体的顶点是二维数组，如下所示：

double vertices[8][3] = {
    { 1.0f, 1.0f, 1.0f}, //0
    { 1.0f, 1.0f,-1.0f}, //1
    { 1.0f,-1.0f,-1.0f}, //2
    {-1.0f,-1.0f,-1.0f}, //3
    {-1.0f,-1.0f, 1.0f}, //4
    {-1.0f, 1.0f, 1.0f}, //5
    {-1.0f, 1.0f,-1.0f}, //6
    { 1.0f,-1.0f, 1.0f}  //7
};

目前我使用线条绘制多维数据集的代码是

void drawLines(){
    glBegin(GL_LINES);
    //Front Lines
    //Left
    glVertex3f(vertices[5][0],vertices[5][1],vertices[5][2]);
    glVertex3f(vertices[4][0],vertices[4][1],vertices[4][2]);
    //Top
    glVertex3f(vertices[5][0],vertices[5][1],vertices[5][2]);
    glVertex3f(vertices[0][0],vertices[0][1],vertices[0][2]);
    //Bottom
    glVertex3f(vertices[4][0],vertices[4][1],vertices[4][2]);
    glVertex3f(vertices[7][0],vertices[7][1],vertices[7][2]);
    //Right
    glVertex3f(vertices[7][0],vertices[7][1],vertices[7][2]);
    glVertex3f(vertices[0][0],vertices[0][1],vertices[0][2]);
    //Middle Lines
    //Top Left
    glVertex3f(vertices[6][0],vertices[6][1],vertices[6][2]);
    glVertex3f(vertices[5][0],vertices[5][1],vertices[5][2]);
    //Top Right
    glVertex3f(vertices[1][0],vertices[1][1],vertices[1][2]);
    glVertex3f(vertices[0][0],vertices[0][1],vertices[0][2]);
    //Bottom Left
    glVertex3f(vertices[3][0],vertices[3][1],vertices[3][2]);
    glVertex3f(vertices[4][0],vertices[4][1],vertices[4][2]);
    //Bottom Right
    glVertex3f(vertices[2][0],vertices[2][1],vertices[2][2]);
    glVertex3f(vertices[7][0],vertices[7][1],vertices[7][2]);
    //Back Lines
    //Left
    glVertex3f(vertices[6][0],vertices[6][1],vertices[6][2]);
    glVertex3f(vertices[3][0],vertices[3][1],vertices[3][2]);
    //Top
    glVertex3f(vertices[6][0],vertices[6][1],vertices[6][2]);
    glVertex3f(vertices[1][0],vertices[1][1],vertices[1][2]);
    //Bottom
    glVertex3f(vertices[3][0],vertices[3][1],vertices[3][2]);
    glVertex3f(vertices[2][0],vertices[2][1],vertices[2][2]);
    //Right
    glVertex3f(vertices[2][0],vertices[2][1],vertices[2][2]);
    glVertex3f(vertices[1][0],vertices[1][1],vertices[1][2]);

    glEnd();                    // Done Drawing Edges
}

这实现了这个结果：

为了压缩我的代码，我试图使用for循环获得相同的结果，目前我有这个：

glBegin(GL_LINES);

for ( int i=0; i<8; i+=1 ) {
    for (int j=0; j<8; j+=1) {
        glVertex3f(vertices[i][0],vertices[i][1],vertices[i][2]);
        glVertex3f(vertices[j][0],vertices[j][1],vertices[j][2]);
    }
}
glEnd();

这给了我这个结果：

我的问题是，是否有人能够给我指导以获得与原始代码相同的结果？

Answer 1

为索引添加数组：

int[12][2] indices = {
    {5,4},
    {5,0},

    {4,7},
    {7,0},

    {6,5},
    {1,0},

    {3,4},
    {2,7},

    {6,3},
    {6,1},

    {3,2},
    {2,1}
}

并循环：

glBegin(GL_LINES);

for ( int i=0; i<12; i+=1 ) {

    glVertex3f(vertices[indices[i][0]][0],vertices[indices[i][0]][1],vertices[indices[i][0]][2]);
    glVertex3f(vertices[indices[i][1]][0],vertices[indices[i][1]][1],vertices[indices[i][1]][2]);
}
glEnd();

但是，建议您不要使用旧的（和已弃用的）openGL进行学习。相反，建议的方法是将顶点数据上传到VBO;创建一组着色器并改为使用glDrawArrays或glDrawElements。

使用for循环的OpenGL多维数据集

1 个答案: