在空间中绘图：线。点、多边形

在空间中绘图：线。点、多边形

三维螺旋线

效果

代码

void RenderScene(void){
GLfloat x,y,z,angle;    //使用当前的清除色清除窗口
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(xRot,1.0f,0.0f,0.0f);
glRotatef(yRot,0.0f,1.0f,0.0f);    //对所有的点调用一次
glBegin(GL_POINTS);
z = -50.0f;
for(angle = 0.0f; angle <= (2.0f*GL_PI)*3.0f;angle += 0.1f)
{
 x = 50.0f*sin(angle);
 y = 50.0f*cos(angle);
glVertex3f(x,y,z);
z += 0.5f;
 }
glEnd();
glPopMatrix();
glFlush();}

改变点大小

效果

代码

void RenderScene(void){
 GLfloat x,y,z,angle;
GLfloat sizes[2];//保存支持点大小的范围
 GLfloat step;   //保存支持的点增长
   GLfloat curSize;//保存当前点大小
 //使用当前的清除色清除窗口
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(xRot,1.0f,0.0f,0.0f);
glRotatef(yRot,0.0f,1.0f,0.0f);    //获取支持点的范围和增长
glGetFloatv(GL_POINT_SIZE_RANGE,sizes);
glGetFloatv(GL_POINT_SIZE_GRANULARITY,&step);    //设置初始点大小
curSize = sizes[0];    //设置z坐标起始值
z = -50.0f;     //对所有的点调用一次

for(angle = 0.0f; angle <= (2.0f*GL_PI)*3.0f;angle += 0.1f)
{
x = 50.0f*sin(angle);
y = 50.0f*cos(angle);
glPointSize(curSize);
glBegin(GL_POINTS);
glVertex3f(x,y,z);
glEnd();
z += 0.5f;
curSize += step;
}
glPopMatrix();
glFlush();
}

扇形

效果

代码

void RenderScene(void){
GLfloat x,y,z,angle;    //使用当前的清除色清除窗口
 glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();     //对所有的点调用一次
glBegin(GL_LINES);
z = 0.0f;
for(angle = 0.0f; angle <= GL_PI*3.0f;angle += 0.5f)
{
x = 50.0f*sin(angle);
y = 50.0f*cos(angle);
glVertex3f(x,y,z);
x = 50.0f*sin(angle+3.1415f);
y = 50.0f*cos(angle+3.1415f);
glVertex3f(x,y,z);
}
glEnd();
glPopMatrix();
glFlush();}

线段的跨接和循环

效果

代码

void RenderScene(void){
GLfloat x,y,z,angle;    //使用当前的清除色清除窗口
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();     //对所有的点调用一次
glBegin(GL_LINE_STRIP);
    glVertex3f(0.0f,0.0f,0.0f);
     glVertex3f(50.0f,50.0f,0.0f);
     glVertex3f(50.0f,100.0f,0.0f);
glEnd();
glPopMatrix();
glFlush();}

将glBegin改为glBegin(GL_LINE_LOOP);后的结果将把最后一个点和第一个点连接起来，形成一个封闭的图形：

线宽度

效果

代码

void RenderScene(void)
{
 GLfloat y;
 GLfloat fSizes[2];
 GLfloat fCurrSize;
 glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
//get line size metrics and save the smallest value
glGetFloatv(GL_LINE_WIDTH_RANGE,fSizes);    //
glGetFloatv(GL_POINT_SIZE_GRANULARITY,&step);
 fCurrSize = fSizes[0];
for(y = -90.0f; y <= 90.0f;y += 20.0f)
  {
//set the line width
  glLineWidth(fCurrSize);
    glBegin(GL_LINES);
     glVertex2f(-80.0f,y);
        glVertex2f(80.0f,y);
      glEnd();
    fCurrSize += 1.0f;
  }