Lane-学习OpenGL(1)-七个简单例子

在看了许多实例之后,

准备沿着OpenGL编程指南(第七版)学习OpenGL.

运行环境:

(1)Windows 7

(2)CodeBlocks

(3)GLUT

(4)Author:Lane

2014-12-02

1.黑色背景加白色矩形

核心函数:glOrtho.(通过注释和修改参数测试,参考http://blog.csdn.net/shizhipeng/article/details/4939529)

#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <cstdlib>
#include <cstdio>
#include <cmath>

void display(void){
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,1.0,1.0);//白色
glBegin(GL_POLYGON);
glVertex3f(0.25,0.25,0.0);
glVertex3f(0.75,0.25,0.0);
glVertex3f(0.75,0.75,0.0);
glVertex3f(0.25,0.75,0.0);
glEnd();
glFlush();//刷新,将缓冲区数据输出
}

void init(void){
glClearColor(0.0,0.0,0.0,0.0);//黑色背景
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0,1.0,0.0,1.0,-1.0,1.0);
}

int main(int argc,char** argv){
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
glutInitWindowPosition(100,100);//窗口位置
glutInitWindowSize(250,250);//窗口大小
glutCreateWindow("hello");//窗口命名
init();
glutDisplayFunc(display);
glutMainLoop();
return 0;
}

2.单击触发旋转事件,鼠标轮轴点击停止的白色矩形

测试glShadeModel(GL_FLAT和GL_SMOOTH)

核心函数glutIdleFunc和glutPostRedisplay.

#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <cstdlib>
#include <cstdio>
#include <cmath>

static GLfloat spin = 0.0;

void init(void){
glClearColor(0.0,0.0,0.0,0.0);//黑色背景
glShadeModel(GL_FLAT);
}

void display(void){
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(spin,0.0,0.0,1.0);
glColor3f(1.0,1.0,1.0);//白色
glRectf(-25.0,-25.0,25.0,25.0);
glPopMatrix();
glutSwapBuffers();//交换缓冲
}

//CPU闲暇时间执行此函数
void spinDisplay(void){
spin = spin + 2.0;
if(spin > 360.0)
spin -= 360.0;
glutPostRedisplay();//标记当前窗口重新绘制
}

void reshape(int w,int h){
glViewport(0,0,(GLsizei) w,(GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();//恢复初始坐标
glOrtho(-50.0,50.0,-50.0,50.0,-1.0,1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();//恢复初始坐标
}

void mouse(int button,int state,int x,int y){
switch(button){
case GLUT_LEFT_BUTTON://单击事件
if(state == GLUT_DOWN)
glutIdleFunc(spinDisplay);//触发旋转事件
break;
case GLUT_MIDDLE_BUTTON://轮轴点击事件
if(state == GLUT_DOWN)
glutIdleFunc(NULL);//去除旋转事件
break;
default:
break;
}
}

int main(int argc,char** argv){
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);//双缓冲
glutInitWindowSize(250,250);
glutInitWindowPosition(100,100);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);//设置变形函数
glutMouseFunc(mouse);//设置鼠标事件
glutMainLoop();
return 0;
}

2014-12-03

3.虚线画线

核心函数glLineStipple(1,0x0101);

第一个参数factor,可以理解为倍数.

第二个参数二进制写出 0000 0001 0000 0001 .

1代表需要绘制,0代表忽略.顺序是二进制的逆序.

即表示绘制1个点->忽略7个点->绘制1个点->忽略7个点.

如果factor为2.

即表示绘制2个点->忽略14个点->绘制2个点->忽略14个点.

#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <cstdlib>
#include <cstdio>
#include <cmath>

#define drawOneLine(x1,y1,x2,y2) glBegin(GL_LINES);glVertex2f((x1),(y1));glVertex2f((x2),(y2));glEnd();

void init(void){
glClearColor(0.0,0.0,0.0,0.0);//黑色背景
glShadeModel(GL_FLAT);
}

void display(void){
int i;

glClear(GL_COLOR_BUFFER_BIT);//设置背景

glColor3f(1.0,1.0,1.0);
glEnable(GL_LINE_STIPPLE);//设置启用虚线
glLineStipple(1,0x0101);
drawOneLine(50.0,125.0,150.0,125.0);
glLineStipple(1,0x00FF);
drawOneLine(150.0,125.0,250.0,125.0);
glLineStipple(1,0x1C47);
drawOneLine(250.0,125.0,350.0,125.0);

glLineWidth(5.0);
glLineStipple(1,0x0101);
drawOneLine(50.0,100.0,150.0,100.0);
glLineStipple(1,0x00FF);
drawOneLine(150.0,100.0,250.0,100.0);
glLineStipple(1,0x1C47);
drawOneLine(250.0,100.0,350.0,100.0);

glLineWidth(1.0);
glLineStipple(1,0x1C47);
glBegin(GL_LINE_STRIP);
for(i = 0; i < 7; i++)
glVertex2f(50.0+((GLfloat) i * 50.0),75.0);
glEnd();
for(i = 0; i < 6; i++){
drawOneLine(50.0 + ((GLfloat) i * 50.0),50.0,50.0+((GLfloat)(i+1)*50.0),50.0);
}
glLineStipple(5,0x1C47);
drawOneLine(50.0,25.0,350.0,25.0);

glDisable(GL_LINE_STIPPLE);
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);
}

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);
glutMainLoop();
return 0;
}

4.多边形画点
核心函数:glPolygonStipple

#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <cstdlib>
#include <cstdio>
#include <cmath>

void display(void){
GLubyte fly[] = {
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x03,0x80,0x01,0xC0,0x06,0xC0,0x03,0x60,
0x04,0x60,0x06,0x20,0x04,0x30,0x0C,0x20,
0x04,0x18,0x18,0x20,0x04,0x0C,0x30,0x20,

0x04,0x06,0x60,0x20,0x04,0x03,0xC0,0x22,
0x44,0x01,0x80,0x22,0x44,0x01,0x80,0x22,
0x44,0x01,0x80,0x22,0x44,0x01,0x80,0x22,
0x44,0x01,0x80,0x22,0x44,0x01,0x80,0x22,

0x66,0x01,0x80,0x66,0x33,0x01,0x80,0xCC,
0x19,0x81,0x81,0x98,0x0C,0xC1,0x83,0x30,
0x07,0xe1,0x87,0xe0,0x03,0x3f,0xfc,0xc0,
0x03,0x31,0x8c,0xc0,0x03,0x33,0xCC,0xC0,

0x06,0x64,0x26,0x60,0x0c,0xcc,0x33,0x30,
0x18,0xcc,0x33,0x18,0x10,0xc4,0x23,0x08,
0x10,0x63,0xc6,0x08,0x10,0x30,0x0c,0x08,
0x10,0x18,0x18,0x08,0x10,0x00,0x00,0x08,
};

GLubyte halftone[] = {
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
};

glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,1.0,1.0);
glRectf(25.0,25.0,125.0,125.0);
glEnable(GL_POLYGON_STIPPLE);
glPolygonStipple(fly);
glRectf(125.0,25.0,225.0,125.0);
glPolygonStipple(halftone);
glRectf(225.0,25.0,325.0,125.0);
glDisable(GL_POLYGON_STIPPLE);
glFlush();
}

void init(void){
glClearColor(0.0,0.0,0.0,0.0);
glShadeModel(GL_FLAT);
}

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);
}

int main(int argc,char** argv){
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
glutInitWindowSize(350,150);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}

5.反馈模式

#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <cstdlib>
#include <cstdio>
#include <cmath>

void init(void){
glEnable(GL_LIGHTING);//启用光源
glEnable(GL_LIGHT0);//启用光源0
}

void drawGeometry(GLenum mode){
glBegin(GL_LINE_STRIP);
glNormal3f(0.0,0.0,1.0);
glVertex3f(30.0,30.0,0.0);
glVertex3f(50.0,60.0,0.0);
glVertex3f(70.0,40.0,0.0);
glEnd();
if(mode == GL_FEEDBACK)
glPassThrough(1.0);
glBegin(GL_POINTS);
glVertex3f(-100.0,-100.0,-100.0);
glEnd();
if(mode == GL_FEEDBACK)
glPassThrough(2.0);
glBegin(GL_POINTS);
glNormal3f(0.0,0.0,1.0);
glVertex3f(50.0,50.0,0.0);
glEnd();
glFlush();
}

void print3DcolorVertex(GLint size,GLint *count,GLfloat *buffer){
int i;
printf(" ");
for(i = 0; i < 7; i++){
printf("%4.2f ",buffer[size-(*count)]);
*count = *count - 1;
}
printf("\n ");
}

void printBuffer(GLint size,GLfloat *buffer){
GLint count;
GLfloat token;

count = size;
while(count){
token = buffer[size-count];
count--;
if(token == GL_PASS_THROUGH_TOKEN){
printf("GL_PASS_THROUGH_TOKEN \n ");
printf(" %4.2f \n ",buffer[size-count]);
count--;
}else if(token == GL_POINT_TOKEN){
printf("GL_POINT_TOKEN \n ");
print3DcolorVertex(size,&count,buffer);
}else if(token == GL_LINE_TOKEN){
printf("GL_LINE_TOKEN \n ");
print3DcolorVertex(size,&count,buffer);
print3DcolorVertex(size,&count,buffer);
}else if(token == GL_LINE_RESET_TOKEN){
printf("GL_LINE_RESET_TOKEN \n ");
print3DcolorVertex(size,&count,buffer);
print3DcolorVertex(size,&count,buffer);
}
}
}

void display(void){
GLfloat feedBuffer[1024];
GLint size;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0,100.0,0.0,100.0,0.0,1.0);

glClearColor(0.0,0.0,0.0,0.0);
glClear(GL_COLOR_BUFFER_BIT);
drawGeometry(GL_RENDER);

glFeedbackBuffer(1024,GL_3D_COLOR,feedBuffer);
(void)glRenderMode(GL_FEEDBACK);
drawGeometry(GL_FEEDBACK);
size = glRenderMode(GL_RENDER);
printBuffer(size,feedBuffer);
}

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

6.变换立方体

核心函数:gluLookAt(参考http://blog.csdn.net/ivan_ljf/article/details/8764737)

核心函数:glFrustum(透视)

#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <cstdlib>
#include <cstdio>
#include <cmath>

void init(void){
glClearColor(0.0,0.0,0.0,0.0);//黑色背景
glShadeModel(GL_FLAT);//单调着色
}

void display(void){
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,1.0,1.0);//白色
glLoadIdentity();//恢复初始坐标系
gluLookAt(0.0,0.0,5.0,0.0,0.0,0.0,0.0,1.0,0.0);
glScalef(1.0,2.0,1.0);//缩放
glutWireCube(1.0);//绘制立方体
glFlush();
}

void reshape(int w,int h){
glViewport(0,0,(GLsizei)w,(GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-1.0,1.0,-1.0,1.0,1.5,20.0);
glMatrixMode(GL_MODELVIEW);
}

int main(int argc,char** argv){
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
glutInitWindowPosition(100,100);
glutInitWindowSize(500,500);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}

7.经过两个裁剪平面裁剪的线框球体

核心函数:glClipPlane

测试gluPerspective(透视)

#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <cstdlib>
#include <cstdio>
#include <cmath>

void init(void){
glClearColor(0.0,0.0,0.0,0.0);//黑色
glShadeModel(GL_FLAT);//单调着色
}

void display(void){
GLdouble eqn[4] = {0.0,1.0,0.0,0.0};//Y轴裁剪
GLdouble eqn2[4] = {1.0,0.0,0.0,0.0};//X轴裁剪

glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,1.0,1.0);

glPushMatrix();
glTranslatef(0.0,0.0,-5.0);
glClipPlane(GL_CLIP_PLANE0,eqn);//启用裁剪平面0
glEnable(GL_CLIP_PLANE0);//启用裁剪0
glClipPlane(GL_CLIP_PLANE1,eqn2);//启用裁剪平面1
glEnable(GL_CLIP_PLANE1);//启用裁剪1
glRotatef(90.0,1.0,0.0,0.0);
glutWireSphere(1.0,20,16);//绘制球体
glPopMatrix();
glFlush();
}

void reshape(int w,int h){
glViewport(0,0,(GLsizei)w,(GLsizei)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60.0,(GLfloat)w/(GLfloat)h,1.0,20.0);
glMatrixMode(GL_MODELVIEW);
}

int main(int argc,char** argv){
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
glutInitWindowSize(500,500);
glutInitWindowPosition(100,100);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}