swing.cpp

openGL中在屏幕上渲染一个秋千

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

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

#define SWING 1
#define BAR 2

GLfloat angle;////angle of swing
int direction;///direction of swing

void CALLBACK reshape(int width,int height);
void CALLBACK draw(void);

void CALLBACK reshape(int width,int height)
{

	///set the new viewpoint size
	glViewport(0,0,(GLint)width,(GLint)height);

	///choose the projection matrix to be the matrix 
	glMatrixMode(GL_PROJECTION);
	
	////set the projection to be the identity matrix
	glLoadIdentity();
 
	///define the dimensions of the orthographtic viewing volume
	glOrtho(-50.0,50.0,-50.0,50.0,-150.0,150.0);

	///choose the modelview matrix to be the matrix
	glMatrixMode(GL_MODELVIEW);
}

void CALLBACK draw(void)
{
	///clear the RGB buffer and the depth buffer
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	/////set the modelview matrix to be the indentity matrix
	glLoadIdentity();

	///rotate the bar and swing
	glRotatef(60.0,0.0,1.0,0.0);

	///draw the bar
	glCallList(BAR);


	//translate and rotate the swing to make it "swing"
	glTranslatef(0.0,30.0,0.0);
	glRotatef(angle,1.0,0.0,0.0);
	glTranslatef(0.0,-30.0,0.0);


	////draw the swing
	glCallList(SWING);

	///flush the bufffer to force drawing of the all objects thus bar
	glFlush();

	///swap the buffers
	auxSwapBuffers();

	///make the is swing back or forth depengding upon direction
	if(direction==1)
		angle++;
	else
		angle--;

	////change the direction if 40 or -40 is reached
	if(angle==40.0){
		direction=1;
	}
	if(angle==-40.0){
		direction=0;
	}

}

void make_bar()
{
	glNewList(BAR,GL_COMPILE);

	/////////Darw the pole
	glBegin(GL_QUADS);

			glColor3f(1.0,1.0,1.0);


			//botom
			glVertex3d(-50,30,-1);
			glVertex3d(50,30,-1);
			glVertex3d(50,30,1);
			glVertex3d(-50,30,1);

			///top
			glVertex3d(-50,33,-1);
			glVertex3d(50,33,-1);
			glVertex3d(50,33,1);
			glVertex3d(-50,33,1);
	        ////turn the color
			glColor3f(1.0f,0.65f,0.0f);
	
			///front
			glVertex3d(-50,33,1);
			glVertex3d(-50,30,1);
			glVertex3d(50,30,1);
			glVertex3d(50,33,1);

			///back
			glVertex3d(50,33,-1);
			glVertex3d(50,30,-1);
			glVertex3d(-50,30,-1);
			glVertex3d(-50,33,-1);
		
			glColor3f(1.0,0.0,0.0);


			////left 
			glVertex3d(-50,33,-1);
			glVertex3d(-50,30,-1);
			glVertex3d(-50,30,1);
			glVertex3d(-50,33,1);

			///right
			glVertex3d(50,33,1);
			glVertex3d(50,30,1);
			glVertex3d(50,30,-1);
			glVertex3d(50,33,-1);

		glEnd();

	glEndList();

}


void make_swing()
{
	glNewList(SWING,GL_COMPILE);

			glColor3f(1.0,0.0,1.0);
			glLineWidth(5.0);

			/////draw the ropes
			glBegin(GL_LINES);
					glVertex3d(-20,30,0);
					glVertex3d(-20,-30,0);
					glVertex3d(20,30,0);
					glVertex3d(20,-30,0);
			glEnd();

			glColor3f(0.0,1.0,0.0);

			///draw the sides of the bar
			glBegin(GL_QUAD_STRIP);
					glVertex3d(20,-30,-10);
					glVertex3d(20,-33,-10);
					glVertex3d(-20,-30,-10);
					glVertex3d(-20,-33,-10);
					glVertex3d(-20,-30,10);
					glVertex3d(-20,-30,10);
					glVertex3d(20,-30,10);
					glVertex3d(20,-33,10);
					glVertex3d(20,-30,-10);
					glVertex3d(20,-33,-10);
			glEnd();

			glColor3f(0.0,0.0,1.0);

			///draw the top and bottom of the seat
			glBegin(GL_QUADS);
					glVertex3d(-20,-33,-10);
					glVertex3d(20,-33,-10);
					glVertex3d(20,-33,10);
					glVertex3d(-20,-33,10);

					glVertex3d(-20,-30,-10);
					glVertex3d(20,-30,-10);
					glVertex3d(20,-30,10);
					glVertex3d(-20,-30,10);
			glEnd();
			glEndList();

}

void main(int argc,char **argv)
{
	///set the left corner of window to be at location(0.0)
	////set the window size to be 500*500
	auxInitPosition(0,0,500,500);

	///initialize the RGB and Depth buffers
	auxInitDisplayMode(AUX_RGB | AUX_DEPTH | AUX_DOUBLE);

	///open a window, name it swing
	auxInitWindow("swing");

	////set the clear color to black
	glClearColor(0.0,0.0,0.0,0.0);

	///set the shade model
	glShadeModel(GL_FLAT);

	/////set the polygon mode to fill
	glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);

	///enable depth testing for hidden line removal
	glEnable(GL_DEPTH_TEST);

	///create the display lists
	make_bar();
	make_swing();

	angle=-39.0;
	direction=1;

	////assign reshape() to be the function called whenever
	///a reshape event occours
	auxReshapeFunc(reshape);

	///assign draw() to be the function called whenever a display
	////event occours,generally after a resize or expose event
	auxMainLoop(draw);
	auxIdleFunc(draw);
}