Question

计算机图形学C语言画图问题

// Draw a white square against a black background
#include <stdio.h>
#include <GL/glut.h>
void draw(){
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(0.0, 0.0, 0.0);
glBegin(GL_TRIANGLES);
glVertex3f(-0.5f, -0.5f, 0.0f);
glVertex3f( 0.5f, -0.5f, 0.0f);
glVertex3f( 0.0f, 0.5f, 0.0f);
glEnd();
glFlush();
}
int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(400,300);
glutInitWindowPosition(200,100);
glutCreateWindow("sample");
glClearColor(1.0,1.0,1.0,0.0);
gluOrtho2D(0.0,400.0,0.0,300.0);
glutDisplayFunc(draw);
glutMainLoop();
}
画个三角形，为什么这代码运行出来是个大白框，求助！！

Answer 1

gluOrtho2D参数不对，参数分别代表（左下角x坐标，右上角x坐标，左下角y坐标，右上角y坐标），相对于窗口左下角。注释掉它看看就知道了