OpenGL GLUT solor system code example

    
        标签：
        
            OpenGL
        
            C++
        
    发布于：2020-04-09 22:55:07
    编辑于：2022-11-15 12:18:53
    浏览量：1321

        /*
title: OpenGL GLUT solor system code example
tags: 
- OpenGL
- C++
*/
#include <GL/glut.h>
#include <Math.h>

const float PI = 3.14159265f;

GLfloat sunRadius = 0.15f;
GLfloat earthRadius = 0.07f;
GLfloat moonRadius = 0.01f;
GLfloat sunTrackRadius = 0.5f;
GLfloat earthTrackRadius = 0.15f; // 0.1
GLfloat sunX = 0.0f;
GLfloat sunY = 0.0f;
GLfloat earthX, earthY, moonX, moonY;
GLfloat earthSpeed = 0.03;
GLfloat moonSpeed = 0.05;
GLfloat currentEarthAngle = 0;
GLfloat currentMoonAngle = 0;

bool isPaused = false;
int refreshMillis = 16;

GLdouble clipAreaXLeft, clipAreaXRight, clipAreaYBottom, clipAreaYTop;

void init()
{
	glClearColor(0.0, 0.0, 0.0, 1.0);
}

void drawCirle(float circleX, float circleY, float radius, float r, float g, float b, int segmantNumber = 100)
{
	glLoadIdentity();  // very important
	glTranslatef(circleX, circleY, 0.0f);
	glBegin(GL_TRIANGLE_FAN);
	glColor3f(r, g, b);
	GLfloat angle;
	for (int i = 0; i <= segmantNumber; i++)
	{
		angle = i * 2.0f * PI / segmantNumber;
		glVertex2f(cos(angle) * radius, sin(angle) * radius);
	}
	glEnd();
}

void circularMove(float centerX, float centerY, float& targetX, float& targetY, float& currentAngle, float speed, float radius)
{
	currentAngle += speed;
	targetX = centerX + cos(currentAngle) * radius;
	targetY = centerY + sin(currentAngle) * radius;
}

void display()
{
	if (isPaused) return;
	glClear(GL_COLOR_BUFFER_BIT);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	circularMove(sunX, sunY, earthX, earthY, currentEarthAngle, earthSpeed, sunTrackRadius);
	circularMove(earthX, earthY, moonX, moonY, currentMoonAngle, moonSpeed, earthTrackRadius);
	drawCirle(sunX, sunY, sunRadius, 1, 0, 0);
	drawCirle(earthX, earthY, earthRadius, 0, 0, 1);
	drawCirle(moonX, moonY, moonRadius, 0.7925, 0.7925, 0.7925);
	glutSwapBuffers();
}

void reshape(GLsizei width, GLsizei height)
{
	if (height == 0) height = 1;
	GLfloat aspect = (GLfloat)width / (GLfloat)height;
	glViewport(0, 0, width, height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	if (width >= height)
	{
		clipAreaXLeft = -1.0 * aspect;
		clipAreaXRight = 1.0 * aspect;
		clipAreaYBottom = -1.0;
		clipAreaYTop = 1.0;
	}
	else
	{
		clipAreaXLeft = -1.0;
		clipAreaXRight = 1.0;
		clipAreaYBottom = -1.0 / aspect;
		clipAreaYTop = 1.0 / aspect;
	}
	gluOrtho2D(clipAreaXLeft, clipAreaXRight, clipAreaYBottom, clipAreaYTop);
}

void timer(int value)
{
	glutPostRedisplay();
	glutTimerFunc(refreshMillis, timer, 0);
}

void keyboard(unsigned char key, int x, int y) {
	switch (key)
	{
	case 32:
		isPaused = !isPaused; break;
	default: break;
	}
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE);
	glutInitWindowSize(1000, 1000);
	glutCreateWindow("solar-system");
	glutDisplayFunc(display);
	glutReshapeFunc(reshape);
	glutKeyboardFunc(keyboard);
	glutTimerFunc(0, timer, 0);
	init();
	glutMainLoop();
	return 0;
}