【计算机图形学】一、直线的生成

1. 算法：

2. 源代码：

#include "stdafx.h"

#include "GL/glut.h"
#include "stdlib.h"
#include "math.h"

void init()
{
	glClearColor(1.0,1.0,1.0,0.0);
	
	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(0.0,200.0,0.0,150.0);
}

inline int round(const float a)
{
	return int(a+0.5);
}

void setPixel(int x, int y)
{
	glBegin(GL_POINTS);
	glVertex2i(x,y);
	glEnd();
}

void lineDDA(int x0,int y0,int xEnd,int yEnd)
{
	int dx=xEnd-x0, dy=yEnd-y0, steps, k;
	float xIncrement, yIncrement, x=x0, y=y0;
	
	if(fabs(dx)>fabs(dy))
		steps=fabs(dx);
	else
		steps=fabs(dy);
	xIncrement=float(dx)/float(steps);
	yIncrement=float(dy)/float(steps);
    
	setPixel(round(x),round(y));
	for(k=0; k<steps; k++)
	{
		x+=xIncrement;
		y+=yIncrement;
		setPixel(round(x),round(y));
	}
	
}

void render()
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(1.0,0.0,0.0);

	lineDDA(0,150,150,0);
	lineDDA(1,1,300,300);

	glFlush();
}

int main(int argc, char* argv[])
{
	glutInit(&argc,argv);
	glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
	glutInitWindowPosition(50,100);
	glutInitWindowSize(600,400);
	glutCreateWindow("Line");
	
	init();
	glutDisplayFunc(render);
	glutMainLoop();
	
	return 0;
}

3. 结果：