看我为了水作业速通 opengl freeglut！

news2024/9/17 0:24:30

参考视频计算机图形学基础–OpenGL的实现_哔哩哔哩_bilibiliT

图形绘制

点

GL_POINTS

#define FREEGLUT_STATIC // Define a static library for calling functions
#include <GL/freeglut.h> // Include the header file

void myPoints() { //show three points in screen
	glClear(GL_COLOR_BUFFER_BIT);
	glPointSize(3);
	glBegin(GL_POINTS); //show what to draw,here we draw points
	glColor3f(1.0, 0.0, 0.0); //color:red
	glVertex2i(-3, 3);//coordinate
	glColor3f(0.0, 1.0, 0.0); //color:green
	glVertex2i(10, 20);//coordinate
	glColor3f(0.0, 0.0, 1.0); //color:blue
	glVertex2i(0, -15);//coordinate
	glEnd();
	glFlush(); //把绘制的缓存推送到屏幕上
}

void init() {
	glClearColor(1.0, 1.0, 1.0, 1.0); //black background
	glMatrixMode(GL_PROJECTION); 
	glLoadIdentity;
	gluOrtho2D(-100, 100, -100, 100); //可以显示的范围

}

int main(int argc, char* argv[]) {
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowPosition(200, 300); //在屏幕中的位置
	glutInitWindowSize(300, 300);
	glutCreateWindow("Display Points");

	init();
	glutDisplayFunc(myPoints); //回调函数
	glutMainLoop();
	return 0;
}

结果:

注意：颜色改一次换一次（废话），如果不改的话那就一直一个颜色

glFlush()很重要！是把图片推送到屏幕上！

线段

GL_LINES

两个两个配对连线

void lines() {
	int p1[] = { 6,4 };
	int p2[] = { 1,1 };
	int p3[] = { 3,7 };
	int p4[] = { 5,1 };
	int p5[] = { 0,4 };
	glClear(GL_COLOR_BUFFER_BIT);//clear
	glColor3f(0.3, 0.1, 0.8); 
	glPointSize(3);
	glBegin(GL_LINES); //这个以及后面几个改的是这里
	glVertex2iv(p1);
	glVertex2iv(p2);
	glVertex2iv(p3);
	glVertex2iv(p4);
	glVertex2iv(p5); //绘制两个线段是因为P5没有匹配的
	glEnd();
	glFlush();
}

GL_LINE

GL_LINE_LOOP

多边形 POLYGON

GL_POLYGON

void polygonTraingle() {
	int p1[] = { 1,3 };
	int p2[] = { 3,0 };
	int p3[] = { 6,0 };
	int p4[] = { 7,3 };
	int p5[] = { 6,6 };
	int p6[] = { 3,6 };
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(0.6, 0.5, 0.2);
	glPointSize(3);
	glBegin(GL_POLYGON); //point first
	glVertex2iv(p1);
	glVertex2iv(p2);
	glVertex2iv(p3);
	glVertex2iv(p4);
	glVertex2iv(p5);
	glVertex2iv(p6);
	glEnd();
	glFlush();
}

结果

GL_TRIANGLES

GL_QUADS

键鼠交互

键盘

glutKeyboardFunc()

这里重点关注一下那个mykeyboard和mian中的glutkeyboardfuc()

#define FREEGLUT_STATIC // Define a static library for calling functions
#include <GL/freeglut.h> // Include the header file


int xd=0, yd = 0;

void myDisplay() {
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(0.8,0.5,0.6);
	glPointSize(5);
	glBegin(GL_POLYGON);
	glVertex2i(10 + xd,10 + yd);
	glVertex2i(20 + xd,10 + yd);
	glVertex2i(20 + xd,0 + yd);
	glVertex2i(10 + xd,0 + yd);
	glEnd();
	glFlush();
}

void myKeyBoard(unsigned char key, int x, int y) {
	switch (key) {
	case 'w':yd++; break;
	case 's':yd--; break;
	case 'a':xd--; break;
	case 'd':xd++; break;
	}
	glutPostRedisplay(); //要求重新绘制窗口的内容
}


void init() {
	glClearColor(1.0, 1.0, 1.0, 1.0); //black background
	glMatrixMode(GL_PROJECTION);

	glLoadIdentity;
	gluOrtho2D(-20, 30, -20, 30); //可以显示的范围
}


void main(int argc, char* argv[]) {
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowPosition(300, 100); //在屏幕中的位置
	glutInitWindowSize(600, 500);
	glutCreateWindow("Key interaction");

	init();
	glutDisplayFunc(myDisplay); //回调函数
	glutKeyboardFunc(myKeyBoard);
	glutMainLoop();
}

效果

可爱粉色方坨坨会随着你的wasd键上下左右移动

鼠标

glutMouseFunc

重点关注一下mouseMotion函数

#define FREEGLUT_STATIC // Define a static library for calling functions
#include <GL/freeglut.h> // Include the header file


GLint xd=0, yd = 0; //GLint 主要用于在OpenGL中处理整数数据，用于配置和表示与图形渲染相关的各种参数和信息。
GLint w = 600, h = 500; 

void myDisplay() {
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(0.8, 0.5, 0.6);
	glPointSize(5);
	glBegin(GL_POLYGON);
	glVertex2i(10 + xd, 10 + yd);
	glVertex2i(20 + xd, 10 + yd);
	glVertex2i(20 + xd, 0 + yd);
	glVertex2i(10 + xd, 0 + yd);
	glEnd();
	glFlush();
}

void mouseMotion(GLint button,GLint state, GLint x,GLint y) { //鼠标的按钮，鼠标是按下还是弹起，x,y
	if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) { //鼠标左键并按下
		xd = x;
		yd = h-y;
		glutPostRedisplay();
	}
}


void init() {
	glClearColor(1.0, 1.0, 1.0, 1.0); //black background
	glMatrixMode(GL_PROJECTION);

	glLoadIdentity;
	gluOrtho2D(0, w, 0, h); //可以显示的范围
}


void main(int argc, char* argv[]) {
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowPosition(300, 100); //在屏幕中的位置
	glutInitWindowSize(w, h);
	glutCreateWindow("Mouse Motion");

	init();
	glutDisplayFunc(myDisplay); //回调函数
	glutMouseFunc(mouseMotion);
	glutMainLoop();
}

结果