OpenGL关于glEnable(GL_LINE_STIPPLE) glLineStipple() glLineWidth() glDisable()的实例

#include <GL/glut.h>
#include <stdlib.h>


#define drawOneLine(x1,y1,x2,y2)  glBegin(GL_LINES);  \
glVertex2f((x1), (y1)); glVertex2f((x2), (y2)); glEnd();
/*“\”的作用是把一行的内容当做两行来处理*/



void init(void)
{
glClearColor(0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
/* GL_SMOOTH采用的顶点颜色渐变颜色着色
* GLFLAT只用定点颜色着色*/
}


void display(void)
{
int i;


glClear(GL_COLOR_BUFFER_BIT);


/* select white for all lines  */
glColor3f(1.0, 1.0, 1.0);


/* in 1st row, 3 lines, each with a different stipple  */
glEnable(GL_LINE_STIPPLE);/*执行后，画虚线*/

glLineStipple(1, 0x0101);  /*  此时模式为Ox3F07（二进制形式为0000000100000001），它所画出来的直线是这样的：
   *  先连续绘制1个像素，然后连续7个像素留空，再连续绘制1个像素，最后7个像素留空
* （注意，首先是从低位开始的）。  */
drawOneLine(50.0, 125.0, 150.0, 125.0);
glLineStipple(1, 0x00FF);  /*  dashed  */
drawOneLine(150.0, 125.0, 250.0, 125.0);
glLineStipple(1, 0x1C47);  /*  dash/dot/dash  */
drawOneLine(250.0, 125.0, 350.0, 125.0);


/* in 2nd row, 3 wide lines, each with different stipple */
glLineWidth(5.0);/* 像素的宽度 */
glLineStipple(1, 0x0101);  /*  dotted  */
drawOneLine(50.0, 100.0, 150.0, 100.0);
glLineStipple(1, 0x00FF);  /*  dashed  */
drawOneLine(150.0, 100.0, 250.0, 100.0);
glLineStipple(1, 0x1C47);  /*  dash/dot/dash  */
drawOneLine(250.0, 100.0, 350.0, 100.0);
glLineWidth(1.0);


/* in 3rd row, 6 lines, with dash/dot/dash stipple  */
/* as part of a single connected line strip         */
glLineStipple(1, 0x1C47);  /*  dash/dot/dash  */
glBegin(GL_LINE_STRIP);
for (i = 0; i < 7; i++)
glVertex2f(50.0 + ((GLfloat)i * 50.0), 75.0);
glEnd();


/* in 4th row, 6 independent lines with same stipple  */
for (i = 0; i < 6; i++) {
drawOneLine(50.0 + ((GLfloat)i * 50.0), 50.0,
50.0 + ((GLfloat)(i + 1) * 50.0), 50.0);
}


/* in 5th row, 1 line, with dash/dot/dash stipple    */
/* and a stipple repeat factor of 5                  */
glLineStipple(5, 0x1C47);  /*  dash/dot/dash  */
drawOneLine(50.0, 25.0, 350.0, 25.0);


glDisable(GL_LINE_STIPPLE);/*与glEnable参数一致*/
glFlush();
}


void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0.0, (GLdouble)w, 0.0, (GLdouble)h);
}


void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 27:
exit(0);
break;
}
}


int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(400, 150);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMainLoop();
return 0;
}