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#include <bits/stdc++.h>
#include <GL/glut.h>
using namespace std;const int MAXN = 1000000; //10w条线段
const int WIDTH = 400;
const int HEIGHT = 300;
uniform_real_distribution<double> u(0, 1);
default_random_engine e;vector<int> v;
void myinit(void){glClearColor(0, 0, 0, 0);        //置背景色glMatrixMode(GL_PROJECTION);//设矩阵模式gluOrtho2D(0.0, WIDTH,  0.0, HEIGHT);  //正交投影窗口
}int main(int argc, char* argv[]){uniform_int_distribution<int> u1(0, 400);uniform_int_distribution<int> u2(0, 300);int n = MAXN * 2;for(int i = 0; i < n; i++){v.push_back(u1(e));v.push_back(u2(e));}//int id = 0;//for(int i = 0; i  < n; i++) {//    cout<<v[id++]<<" "<<v[id++]<<endl;//}glutInit(&argc, argv);glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);glutInitWindowSize(800,600);glutInitWindowPosition(0,0);glutCreateWindow("line algorithm");//glutDisplayFunc(Bresenham);glutDisplayFunc(DDA);myinit();glutMainLoop();
}

DDA

void DDA(){int st = clock();int id = 0;glClear(GL_COLOR_BUFFER_BIT);  //清除glPointSize(1.0f);for(int i = 0; i < MAXN; i++){glColor3f(u(e),u(e),u(e));   //绘制颜色double x0 = v[id++], y0 = v[id++];double x1 = v[id++], y1 = v[id++];double dx = x1 - x0, dy = y1 - y0;double step = max(fabs(dx), fabs(dy));double ax = dx / step;double ay = dy / step;glBegin(GL_POINTS);for(int j = 0; j < step; j++){glVertex2i(floor(x0 + 0.5), floor(y0 + 0.5));x0 += ax;y0 += ay;}glEnd();}glutSwapBuffers();int ed = clock();cout<<"DDA: "<<ed - st<<"\n";
}

Bresenham

void Bresenham(void){int st = clock();int id = 0;glClear(GL_COLOR_BUFFER_BIT);glPointSize(1.0f);for(int i = 0; i < MAXN; i++){glColor3f(u(e),u(e),u(e));   //绘制颜色int x0 = v[id++], y0 = v[id++], x1 = v[id++], y1 = v[id++];if(x0 > x1 ){swap(x0, x1);swap(y0, y1);}int x = x1 - x0, y = y1 - y0;int step = max(abs(x), abs(y));int x2 = x * 2, y2 = y * 2;glBegin(GL_POINTS);if(y > 0){//m is the slope of the line//cout<<"m > 0 ";if(abs(x) > abs(y)){//cout<<"m < 1\n";int p0 = y2 - x;for(; x0 <= x1; x0++){glVertex2i(x0, y0);if(p0 < 0) {p0 = p0 + y2;}else{p0 = p0 + y2 - x2;y0++;}}}else {//cout<<"m > 1\n";swap(x0, y0);swap(x1, y1);swap(x2, y2);swap(x, y);int p0 = y2 - x;for(; x0 <= x1; x0++){glVertex2i(y0, x0);if(p0 < 0) {p0 = p0 + y2;}else{p0 = p0 + y2 - x2;y0++;}}}}else{//cout<<"m < 0  ";if(abs(x) > abs(y)){//cout<<"m > -1\n";int p0 = y2 + x;for(; x0 <= x1; x0++){glVertex2i(x0, y0);if(p0 > 0) {p0 = p0 + y2;}else{p0 = p0 + y2 + x2;y0--;}}}else {//cout<<"m < -1\n";swap(x0, y0);swap(x1, y1);swap(x2, y2);swap(x, y);int p0 = y2 + x;for(; x0 <= x1; x0++){glVertex2i(y0, x0);if(p0 > 0) {p0 = p0 + y2;}else{p0 = p0 + y2 + x2;y0--;}}}}glEnd();}glutSwapBuffers();int ed = clock();cout<<"Bresenham: "<<ed - st<<"\n";
}

DDABresenham

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DDA

Bresenham

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