OpenGL学习笔记 之一 （基本的图形绘制）

参考网址：http://www.cnblogs.com/FredCong/archive/2012/10/13/2722893.html

 

#include <glut.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

void myDisplay1(void)
{

    glClear(GL_COLOR_BUFFER_BIT);
    glRectf(-0.5f, -0.5f, 0.5f, 0.5f);
    glFlush();
}

void myDisplay2()
{

    glClear(GL_COLOR_BUFFER_BIT);
    glBegin(GL_LINES);//GL_POINTS GL_LINE_STRIP，GL_LINE_LOOP，GL_TRIANGLES，GL_TRIANGLE_STRIP，GL_TRIANGLE_FAN
    glVertex2f(-0.5f, -0.5f);//LINE1
    glVertex2f(0.5f, 0.5f);//LINE1
    glVertex2f(-0.5f, 0.5f);//LINE2
    glVertex2f(0.5f, -0.5f);//LINE2
    glEnd();
    glFlush();
}
const int n = 100;
const GLfloat R = 0.5f;
const GLfloat Pi = 3.1415926f;
void myDisplay3()
{
    int i;
    glClear(GL_COLOR_BUFFER_BIT);
    glBegin(GL_POLYGON);
    for (i=0; i<n; ++i)
    {
        glVertex2f(R*cos(2*Pi/n*i), R*sin(2*Pi/n*i));
    }
    glEnd();
    glFlush();
}
void myDisplay4(void)
{
    GLfloat a = 1 / (2-2*cos(72*Pi/180));
    GLfloat bx = a * cos(18 * Pi/180);
    GLfloat by = a * sin(18 * Pi/180);
    GLfloat cy = -a * cos(18 * Pi/180);
    GLfloat
        PointA[2] = { 0, a },
        PointB[2] = { bx, by },
        PointC[2] = { 0.5, cy },
        PointD[2] = { -0.5, cy },
        PointE[2] = { -bx, by };

    glClear(GL_COLOR_BUFFER_BIT);
    // 按照A->C->E->B->D->A的顺序，可以一笔将五角星画出
    glBegin(GL_LINE_LOOP);
    glVertex2fv(PointA);
    glVertex2fv(PointC);
    glVertex2fv(PointE);
    glVertex2fv(PointB);
    glVertex2fv(PointD);
    glEnd();
    glFlush();
}
void myDisplay5()
{

    glClear(GL_COLOR_BUFFER_BIT);
    //glLineWidth(5.0f);
    //glPointSize(2.0f);
    glEnable(GL_LINE_STIPPLE);
    glLineStipple(1, 0X0f01);//第一个参数是单位像素点的个数， 第二个参数16位，每位控制了param1 个像素点是否显示
    glBegin(GL_LINES);
        glVertex2f(-1.0f, 0.0f);
        glVertex2f(1.0f,0.0f);
        glVertex2f(0.0f,-1.0f);
        glVertex2f(0.0f,1.0f);
    glEnd();
    glBegin(GL_LINE_STRIP);
        for (int i=0; i<100; i++)
            glVertex2f(1.0f/100*i, 0.5*cos(2.0f*Pi/100*i));
    glEnd();
    glFlush();
}
void myDisplay6()
{
    glClear(GL_COLOR_BUFFER_BIT);
    glPolygonMode(GL_FRONT,GL_FILL);//设置正面的显示模式 填充
    glPolygonMode(GL_BACK, GL_LINE);//设置反面的现实模式 线形
    glFrontFace(GL_CCW);//设置哪个是正面，这里将逆时针设置为多边形的正面
    glBegin(GL_POLYGON);
    glVertex2f(-0.5f, -0.5f);//逆时针画一个多边形
    glVertex2f(0.0f, -0.5f);
    glVertex2f(0.0f, 0.0f);
    glVertex2f(-0.5f, 0.0f);
    glEnd();
    glBegin(GL_POLYGON);
    glVertex2f(0.0f,0.0f);//顺时针刷一个多边形
    glVertex2f(0.0f, 0.5f);
    glVertex2f(0.5f, 0.5f);
    glVertex2f(0.5f, 0.0f);
    glEnd();
    glFlush();

}
void myDisplay7()
{
    static GLubyte Mask[128];
    FILE *fp;
    fp = fopen("C:\\Users\\sunny\\Desktop\\mask.bmp", "rb");//32x32尺寸单色图像，每个像素占用1bit，坐标原点可能是在左下角
    if(!fp)
        exit(0);
    if(fseek(fp, -(int)sizeof(Mask), SEEK_END))//直接从后128byte开始读取，这样是为了跳过bmp文件头
        exit(0);
    if(!fread(Mask, sizeof(Mask), 1,fp))
        exit(0);
    fclose(fp);
    glClear(GL_COLOR_BUFFER_BIT);
    glEnable(GL_POLYGON_STIPPLE);
    glPolygonStipple(Mask);
    glRectf(-0.5f, -0.5f, 0.0f, 0.0f); 
    glDisable(GL_POLYGON_STIPPLE);
    glRectf(0.0f, 0.0f, 0.5f, 0.5f);     // 在右上方绘制一个无镂空效果的正方形
    glFlush();

}
int main(int argc, char* argv[])
{

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB|GLUT_SINGLE);
    glutInitWindowPosition(100,100);
    glutInitWindowSize(400,400);
    glutCreateWindow("我的第一个opengl程序");
    glutDisplayFunc(&myDisplay7);
    glutMainLoop();
    return 0;
}

 

 

myDisplay1～7的效果

mask：