OpenGL---箱子沿斜面下滑

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假设箱子只受重力。

#include <windows.h> #include <gl/Gl.h>#include <gl/Glu.h>#include <gl/glut.h>#include "math.h"#include "vector2.h"#pragma comment(lib, "glut.lib")const int windowWidth = 800;const int windowHeight = 600;const double    rads_per_deg = 0.01745;  //度换算成弧度const double    pixels_per_meter = 10;   //米换算成像素const double    g           = 9.81;      //重力加速度 9,81 m/s^2double          theta       = 30;        //坡度double      mass    = 1;        //箱子的重量，1kgbool simulation_over = false;   //箱子移动是否结束double  box_pos = 0;            //箱子的位置double  box_vel = 0;            //箱子的速度Vector2         force_grav;     //箱子所受重力LARGE_INTEGER   clock_freq;   LARGE_INTEGER   last_time;void myDisplay(void) {     glClear(GL_COLOR_BUFFER_BIT);  //清屏    glColor3f( 1, 1, 1 );    //箱子所受重力    force_grav.x = mass * g * sin( theta * rads_per_deg );    force_grav.y = -mass * g * cos( theta * rads_per_deg );    LARGE_INTEGER i;    QueryPerformanceCounter( &i );    double elapsed_time = double( i.QuadPart - last_time.QuadPart ) / clock_freq.QuadPart;    last_time = i;    if(! simulation_over )     {        //F = ma -> a = F/m        double acc = force_grav.x / mass;    //加速度        box_vel += ( acc * elapsed_time );   //速度        box_pos += ( box_vel * pixels_per_meter ) * elapsed_time;  //位置    }    if( box_pos >= 600 )     {        simulation_over = true;    }    //地面    glBegin( GL_LINES );        glVertex2i( 700, 100 );        glVertex2i( 100, 100 );    glEnd();    double dw = 600;    //斜面，原始位置为（700，100）    glPushMatrix();          //原点        glTranslatef( 700, 100, 0 );        glRotatef( -theta, 0, 0, 1);        //斜坡        glBegin( GL_LINES );            glVertex2i( 0, 0 );            glVertex2i( -dw, 0 );        glEnd();        //箱子的位置        glTranslatef( box_pos-dw, 50, 0 );        //箱子        glBegin( GL_LINE_LOOP );            glVertex2i( -50, 50 );            glVertex2i( 50, 50 );            glVertex2i( 50, -50 );            glVertex2i( -50, -50 );        glEnd();    glPopMatrix();    glutSwapBuffers();    glutPostRedisplay();} void myInit(){    glMatrixMode( GL_PROJECTION );     glLoadIdentity();    gluOrtho2D( 0, windowWidth, 0, windowHeight );    glClearColor(0, 0, 0, 0);      //背景颜色是黑色    glViewport(0, 0, windowWidth, windowHeight);}int main(int argc, char *argv[]) {     if( QueryPerformanceFrequency( &clock_freq ) )     {        QueryPerformanceCounter( &last_time );        glutInit(&argc, argv);         glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);         glutInitWindowPosition(50, 50);         glutInitWindowSize(windowWidth, windowHeight);        glutCreateWindow("DEMO");         myInit();        glutDisplayFunc(myDisplay);     }    glutMainLoop();     return 0; }

vector2.h

#ifndef _Vector2_H#define _Vector2_H#include <cmath>#include <iostream>using namespace std;class Vector2 {public:    // vars    float x, y;    // constructors    Vector2() {}    Vector2( float x1, float y1 ) : x(x1), y(y1) {}    // vector ops    void normalize()     {        float temp = 1 / length();        x *= temp;        y *= temp;    }    inline double length() const     {        return( sqrt((x * x) + (y * y)) );    }    Vector2 perp() const     {        return( Vector2( y, -x ) );    }    //  operators    Vector2 operator + ( const Vector2 & rhs ) const     {        return( Vector2(x + rhs.x, y + rhs.y) );    }    Vector2 operator - ( const Vector2 & rhs ) const     {        return( Vector2( x - rhs.x, y - rhs.y ) );    }    Vector2 operator / ( float k ) const     {        return( Vector2(x / k, y / k) );    }    float operator * ( const Vector2 & rhs ) const     {        // dot product        return( (x * rhs.x) + (y * rhs.y) );    }    Vector2 operator * ( const float & rhs ) const     {        // scale by scalar        return( Vector2( x * rhs, y * rhs ) );    }    bool operator == ( const Vector2 & rhs )     {        return( rhs.x == x && rhs.y == y );    }    friend Vector2 operator * ( const float & lhs, const Vector2 & rhs )     {        // scale by scalar        return( Vector2( rhs.x * lhs, rhs.y * lhs ) );    }    friend istream & operator >> ( istream & i, Vector2 & v )     {        i >> v.x >> v.y;        return( i );    }    friend ostream & operator << ( ostream & o, Vector2 & v )     {        o << v.x << " " << v.y;        return( o );    }}; // end class#endif // _Vector2_H

这里写图片描述

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