opengl鼠标画圆

计算机图形学的第二次作业，使用了Bresenham方法。 使用Visual studio 2019，管理NuGet程序包添加nupengl，复制代码就能直接运行。

运行时直接左键点击就可拖拽画圆。

#include <string> #include <assert.h> #include <cmath> #include <iostream> #include <vector> #include <GL/glut.h> using namespace std; typedef vector<int> list; vector<list> cs; int old_x, old_y, new_x, new_y, cx, cy, cr; int mouse_type; // draw point void drawPoint(int x, int y) { /* Draw a point */ //glPointSize(2.0f); glBegin(GL_POINTS); glColor3f(1.0, 0.0, 0.0); // Red glVertex2i(x, y); glEnd(); } // HomeWork void Bresenham_Circle(int xc, int yc, int r) { int x, y, d; x = 0; y = r; d = 5 - 4 * r; drawPoint(x + xc, y + yc); while (x < y) { if (d < 0) d = d + 8 * x + 12; else { d = d + 8 * (x - y) + 20; y--; } x++; drawPoint(x + xc, y + yc); drawPoint(y + xc, x + yc); drawPoint(y + xc, -x + yc); drawPoint(x + xc, -y + yc); drawPoint(-x + xc, -y + yc); drawPoint(-y + xc, -x + yc); drawPoint(-x + xc, y + yc); drawPoint(-y + xc, x + yc); } } void draw() { int i; for (i = 0; i < cs.size(); ++i) Bresenham_Circle(cs[i][0], cs[i][1], cs[i][2]); if (mouse_type == 3) Bresenham_Circle(cx, cy, cr); } void display() { glClear(GL_COLOR_BUFFER_BIT); glColor3i(0, 0, 0); draw(); glutSwapBuffers(); } void mouseclick(int button, int state, int x, int y) { cout << "(" << x << "," << y << ")"; switch (button) { case GLUT_LEFT_BUTTON: if (state == GLUT_DOWN) { cx = x; cy = 600 - y; mouse_type = 3; } else if (state == GLUT_UP) { list l; l.push_back(cx); l.push_back(cy); cr = int(sqrt(double(x - cx) * (x - cx) + (600 - y - cy) * (600 - y - cy)) + 0.5); l.push_back(cr); cs.push_back(l); mouse_type = 2; glutPostRedisplay(); for (int i = 0; i < cs.size(); ++i) cout << endl << "circle_" << i << ": " << cs[i][0] << "," << cs[i][1] << " " << cs[i][2]; } break; case GLUT_MIDDLE_BUTTON: break; case GLUT_RIGHT_BUTTON: break; } } void screenmotion(int x, int y) { if (mouse_type == 3) { cr = int(sqrt(double(x - cx) * (x - cx) + (600 - y - cy) * (600 - y - cy)) + 0.5); cout << endl << "new-circle: " << cx << "," << cy << " " << cr << endl; } glutPostRedisplay(); } void init() { glClearColor(1.0, 1.0, 1.0, 0.0); glMatrixMode(GL_PROJECTION); gluOrtho2D(-1.0, 600, 0.0, 601); } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); glutInitWindowPosition(100, 50); glutInitWindowSize(600, 600); glutCreateWindow("OpenGL"); init(); glutDisplayFunc(display); glutMotionFunc(screenmotion); glutMouseFunc(mouseclick); glutMainLoop(); return 0; }

实验结果：

参考链接: https://blog.csdn.net/baidu_41560343/article/details/101060204