OpenGL织梦之旅【第四章】第2节．简单的3D动画

上一小节中，我们已经成功地搭建好了一个“小剧场”，“观众席”已经设置好了，但是“演员”还没有到位。所以这一小节，我们就来请一些“演员”，让他们做一些“动作”。

还记得读取纹理那章的内容吧~2D纹理在这里同样是可以使用的。为了方便，我把LoadBitmap函数放到了"bmpLoader.h"中，这样方便调用。

在bmpLoader.h中：

但是，我们还没有给他“剧本”，所以他们是不会动的！
在这个init()-Update()-Draw()框架中，Update()函数会每分钟执行很多次，Update来负责这个给定剧本工作的。


附本节全部代码：
#include <GL/glut.h>   #include <stdio.h>   #include <math.h>   #include <time.h>   #include <iostream>#include "bmpLoader.h"#define PI 3.1415926   int WinWidth,WinHeight;double posX,posY,posZ,viewX,viewY,viewZ,upX,upY,upZ;struct point3D{double x;double y;double z;};point3D box[3];GLint boxTexture;void setAll(double px,double py,double pz,double vx,double vy,double vz,double ux,double uy,double uz){posX=px;posY=py;posZ=pz;viewX=vx;viewY=vy;viewZ=vz;upX=ux;upY=uy;upZ=uz;}void setLookAt(){gluLookAt(posX,posY,posZ,  viewX,viewY,viewZ,  upX,upY,upZ);}void setPos(double x,double y,double z){posX=x;posY=y;posZ=z;}void DrawBox(float bx,float by,float bz){glPushAttrib(GL_CURRENT_BIT); glPushMatrix();glTranslatef(bx,by,bz);glEnable(GL_TEXTURE_2D);glBindTexture(GL_TEXTURE_2D, boxTexture);glBegin(GL_QUADS);glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,  1.0f,  1.0f);glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,  1.0f,  1.0f);glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f);glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f);glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);glEnd();glPopMatrix();glPopAttrib();glDisable(GL_TEXTURE_2D);}void DrawGrid(){glPushAttrib(GL_CURRENT_BIT);glLineWidth(2);glColor3f(0.0,1.0,1.0);for (int i=-100; i<=100; i+=10){glBegin(GL_LINES);glVertex3f(i,0.0f,-100.0f);glVertex3f(i,0.0f,100.0f);glEnd();glBegin(GL_LINES);glVertex3f(-100.0f,0.0f,i);glVertex3f(100.0f,0.0f,i);glEnd();}glPopAttrib();}void Draw(){    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);DrawBox(box[0].x,box[0].y,box[0].z);DrawBox(box[1].x,box[1].y,box[1].z);DrawBox(box[2].x,box[2].y,box[2].z);DrawGrid();glutSwapBuffers();}void Update(){static int count;if (count >= 0){box[0].y+=0.02;box[1].y+=0.04;box[2].y+=0.08;}else{box[0].y-=0.02;box[1].y-=0.04;box[2].y-=0.08;}count++;if (count == 100)count=-count;glLoadIdentity();setLookAt();    glutPostRedisplay();}void Reshape(int w,int h){WinWidth=w;WinHeight=h;glMatrixMode(GL_PROJECTION);glLoadIdentity();    glViewport(0,0,w,h);gluPerspective(45,1.0*w/h,1,1000);glMatrixMode(GL_MODELVIEW);glLoadIdentity();}void init(){glClearColor(0.0,0.0,0.0,0.0);glEnable(GL_DEPTH_TEST);setAll(20,1.75,0,0,1.75,0,0,1,0);boxTexture=LoadBitmap("Box.bmp");box[0].x=-2.0;box[0].y=0.5;box[0].z=0.0;box[1].x=0.0;box[1].y=0.5;box[1].z=0.0;box[2].x=2.0;box[2].y=0.5;box[2].z=0.0;}void ProcessKeyboard(unsigned char key,int x,int y){static double delta;if (key == 'a'){delta+=0.03;}if (key == 'd'){delta-=0.03;}setPos(20*cos(delta),posY,20*sin(delta));}int main(int argc, char *argv[]){WinWidth=400;WinHeight=400;    glutInit(&argc, argv);    glutInitDisplayMode(GLUT_DEPTH | GLUT_RGB | GLUT_DOUBLE);    glutInitWindowPosition(100, 100);    glutInitWindowSize(WinWidth, WinHeight);    glutCreateWindow("HelloOpenGL");    glutReshapeFunc(&Reshape);    glutIdleFunc(&Update);    glutDisplayFunc(&Draw);glutKeyboardFunc(&ProcessKeyboard);init();    glutMainLoop();    return 0;  }
作者：plusplus7
日期：2013年3月1日
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