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OpenGL GL_POLYGON concave polygon doesn't color in（1个答案）
6个月前关闭。
我有一个问题，当opengl无法读取顶点的某个部分时，我该怎么办？我的意思是，当我运行代码时，它没有遵循我在坐标纸上所做的坐标网格，即使我删除了那个顶点，它仍然显示相同的输出。我想做枫叶。
我想通过降低某个顶点的y值，用直线画出一条曲线，但是当我运行代码时，它没有画出我已经设定好的坐标，而是跳过了我设定的那个顶点，转到了另一个顶点，画出了一条直线。
假设我对顶点A设（-0.44，0.16）B（-0.46，0.16）C（-0.52，0.18）D（-0.54，0.24），它不是从A到B再到C，而是跳过B和C，去了D。

# include <windows.h>

# include <gl/glut.h>

void display() {

    glClearColor(0.3, 0.1, 0.1, 0.2);
    glClear(GL_COLOR_BUFFER_BIT);

    //glTranslatef(0.5, 0, 0);
    //glScalef(0.5, 0.5, 0);
    //glRotatef(0, 0, 0, 0);

    //Unifolié also known as Maple Leaf
    glBegin(GL_POLYGON);
    glColor3f(1, 0, 0);
    glVertex2f(0.00, 0.00);
    glVertex2f(0.00, 0.90);
    glVertex2f(-0.08, 0.70);
    glVertex2f(-0.12, 0.66);
    glVertex2f(-0.16, 0.66);
    glVertex2f(-0.20, 0.68);
    glVertex2f(-0.24, 0.74);
    glVertex2f(-0.22, 0.64);
    glVertex2f(-0.22, 0.62);
    glVertex2f(-0.24, 0.56);
    glVertex2f(-0.26, 0.54);
    glVertex2f(-0.30, 0.54);
    glVertex2f(-0.34, 0.56);
    glVertex2f(-0.36, 0.60);
    glVertex2f(-0.36, 0.56);
    glVertex2f(-0.38, 0.54);
    glVertex2f(-0.40, 0.54);
    glVertex2f(-0.42, 0.54);
    glVertex2f(-0.56, 0.60);
    glVertex2f(-0.52, 0.54);
    glVertex2f(-0.50, 0.50);
    glVertex2f(-0.48, 0.44);
    glVertex2f(-0.48, 0.42);
    glVertex2f(-0.50, 0.38);
    glVertex2f(-0.54, 0.34);
    glVertex2f(-0.48, 0.32);
    glVertex2f(-0.44, 0.28);
    glVertex2f(-0.42, 0.22);
    glVertex2f(-0.42, 0.20);
    glVertex2f(-0.44, 0.16);
    glVertex2f(-0.46, 0.16); //this 1st
    glVertex2f(-0.52, 0.18);
    glVertex2f(-0.54, 0.24);
    glVertex2f(-0.54, 0.20);
    glVertex2f(-0.56, 0.16);
    glVertex2f(-0.60, 0.14);
    glVertex2f(-0.62, 0.14);
    glVertex2f(-0.70, 0.16);
    glVertex2f(-0.76, 0.20);
    glVertex2f(-0.78, 0.24);
    glVertex2f(-0.76, 0.18);
    glVertex2f(-0.74, 0.14);
    glVertex2f(-0.70, 0.08);
    glVertex2f(-0.68, 0.06);
    glVertex2f(-0.66, 0.02);
    glVertex2f(-0.66, 0.00);
    glVertex2f(-0.68, -0.04);
    glVertex2f(-0.64, -0.02);
    glVertex2f(-0.62, -0.02);
    glVertex2f(-0.56, -0.04);
    glVertex2f(-0.52, -0.08);
    glVertex2f(-0.48, -0.16);
    glVertex2f(-0.48, -0.20);
    glVertex2f(-0.50, -0.26);
    glVertex2f(-0.52, -0.30);
    glVertex2f(-0.58, -0.34);
    glVertex2f(-0.42, -0.32);
    glVertex2f(-0.30, -0.28);
    glVertex2f(-0.18, -0.22);
    glVertex2f(-0.10, -0.20);
    glVertex2f(0.00, -0.22);

    glVertex2f(0.10, -0.20);
    glVertex2f(0.18, -0.22);
    glVertex2f(0.30, -0.28);
    glVertex2f(0.42, -0.32);
    glVertex2f(0.58, -0.34);
    glVertex2f(0.52, -0.30);
    glVertex2f(0.50, -0.26);
    glVertex2f(0.48, -0.20);
    glVertex2f(0.48, -0.16);
    glVertex2f(0.52, -0.08);
    glVertex2f(0.56, -0.04);
    glVertex2f(0.62, -0.02);
    glVertex2f(0.64, -0.02);
    glVertex2f(0.68, -0.04);
    glVertex2f(0.66, 0.00);
    glVertex2f(0.66, 0.02);
    glVertex2f(0.68, 0.06);
    glVertex2f(0.70, 0.08);
    glVertex2f(0.74, 0.14);
    glVertex2f(0.76, 0.18);
    glVertex2f(0.78, 0.24);
    glVertex2f(0.76, 0.20);
    glVertex2f(0.70, 0.16);
    glVertex2f(0.62, 0.14);
    glVertex2f(0.60, 0.14);
    glVertex2f(0.56, 0.16);
    glVertex2f(0.54, 0.20);
    glVertex2f(0.54, 0.24);
    glVertex2f(0.52, 0.18);
    glVertex2f(0.46, 0.16);
    glVertex2f(0.44, 0.16);
    glVertex2f(0.42, 0.20);
    glVertex2f(0.42, 0.22);
    glVertex2f(0.44, 0.28);
    glVertex2f(0.48, 0.32);
    glVertex2f(0.54, 0.34);
    glVertex2f(0.50, 0.38);
    glVertex2f(0.48, 0.42);
    glVertex2f(0.48, 0.44);
    glVertex2f(0.50, 0.50);
    glVertex2f(0.52, 0.54);
    glVertex2f(0.56, 0.60);
    glVertex2f(0.42, 0.54);
    glVertex2f(0.40, 0.54);
    glVertex2f(0.38, 0.54);
    glVertex2f(0.36, 0.56);
    glVertex2f(0.36, 0.60);
    glVertex2f(0.34, 0.56);
    glVertex2f(0.30, 0.54);
    glVertex2f(0.26, 0.54);
    glVertex2f(0.24, 0.56);
    glVertex2f(0.22, 0.62);
    glVertex2f(0.22, 0.64);
    glVertex2f(0.24, 0.74);
    glVertex2f(0.20, 0.68);
    glVertex2f(0.16, 0.66);
    glVertex2f(0.12, 0.66);
    glVertex2f(0.08, 0.70);
    glVertex2f(0.00, 0.90);
    glEnd();

    glFlush();

}

int main(int argc, char* argv[]) {
    glutInit(&argc, argv);
    glutInitWindowSize(1000, 1000);
    glutInitWindowPosition(10, 10);
    glutCreateWindow("Maple Leaf");
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}