计算机图形学 实验一 旋转的圆与三角形(OPEN_GL入门第一战)

　　图形学的实验。

实验内容 实验一：OpenGL 基本使用

实验目的： 自行配置 OpenGL 环境，熟悉使用 OpenGL

基本要求：

　　 在屏幕上绘制出一个三角形和一个圆形，分别填充上你喜欢的颜色

　　 可以使用鼠标分别拖动和旋转他们。

实现：

　　左键平移，右键旋转，Q退出。如果想立体旋转可以选择将display中的glRotate函数改成x,y轴旋转。查一下该函数用法就知道怎么改了。

　　

#include<GL/glut.h>
#define EXIT_SUCCESS 0
#include<stdio.h>
#include<math.h>
// later Edition
bool mouseLeftDown;     // 实时记录鼠标左键状态
bool mouseRightDown;    // 实时记录鼠标左键状态
float mouseX, mouseY;   // 实时记录鼠标位置，与下一次鼠标位置之间形成微分
float triangleAngleX=0; // 存储三角形的X角度积分
float triangleAngleY=0; // 存储三角形的Y角度积分

float CircleAngleX=0;   // 存储圆形的X角度积分
float CircleAngleY=0;   // 存储圆形的Y角度积分

float PI = 3.415926535;

float triangleBiasX = 0.6;//三角形偏倚X
float triangleBiasY = 0.6;//三角形偏倚Y

int selected = 0;       // -0:未选中 -1:选中三角形 -2:选中圆形
float circleBiasX = 0.0;//圆形偏倚X
float circleBiasY = 0.0;//圆形偏倚Y

int added_z_mode =-1;

void init(void)
{
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glMatrixMode(GL_MODELVIEW);
}


void reshape(int w, int h)
{
    glViewport(0, 0, (GLsizei)w, (GLsizei)h);

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    if (w <= h)

        glOrtho(-1.5, 1.5, -1.5 * (GLfloat)h / (GLfloat)w, 1.5 * (GLfloat)h / (GLfloat)w, -10.0, 10.0);

    else

        glOrtho(-1.5 * (GLfloat)w / (GLfloat)h, 1.5 * (GLfloat)w / (GLfloat)h, -1.5, 1.5, -10.0, 10.0);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

}

void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glColor3f(1.0, 1.0, 0);
    
    //进行视角的初始化
    glLoadIdentity();
    gluLookAt(0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0);

    // ========================圆形的部分==========================
    glPushMatrix();
    // 移动
    glTranslatef(circleBiasX, circleBiasY, 0);                          // 相对于世界原点移动

    //对圆形所在的 模型坐标系 执行旋转，翻转操作

    glRotatef(CircleAngleX+CircleAngleY, 0, 0, 1);// 取消了Z轴旋转功能


    
    // 绘制圆形
    float R = 0.25f;
    int n = 80;            
    glBegin(GL_POLYGON);
    for (int i = 0; i < n; i++)                                         // 通过数学计算来画多边形 拟合圆
    {
        glColor3f(1- sin(4.0 * i * PI / 80),sin(2.0 * i * PI / 80),0);
        glVertex2f(R * cos(2* PI * i / n), R * sin(2 * PI * i / n));
    }
    glEnd();
    glTranslatef(-circleBiasX, -circleBiasY, 0);                        // 复位动
    glPopMatrix();                                                      // 将当前圆形状态区压栈,并且切换回原来的坐标远原点


    

    //=============================================================


    // ==========================三角形============================
    glPushMatrix();
    glTranslatef(triangleBiasX, triangleBiasY, 0);                      // 相对于世界原点移动


    // 对三角型所在的 模型坐标系 执行旋转，翻转操作
  
    glRotatef(triangleAngleX+triangleAngleY, 0, 0, 1);                  // 取消又恢复了Z轴旋转
 

        
    
    
    // 绘制三角形
    glBegin(GL_TRIANGLES);
    glColor3f(1.0, 1.0, 0.7);
    glVertex3f(0, 2.0 / 4, 0);
    glColor3f(0.0, 1.0, 0);
    glVertex3f(-1.732 / 4, -1.0 / 4, 0);
    glColor3f(1.0, 1.0, 0.0);
    glVertex3f( 1.732 / 4, -1.0 / 4, 0);
    glEnd();

    glTranslatef(-triangleBiasX, -triangleBiasY, 0);                    // 复位
    glPopMatrix();
    // ============================================================
    // 将状态全部弹出
    
    
    glutSwapBuffers();
}
int saveStack = 0;
int firstSaveFlag = -1;
void keyboard(unsigned char key, int x, int y)

{
    switch (key) {
    case 033: case 'q': case 'Q':// 退出
        exit(EXIT_SUCCESS);
        break;
    }    
}


void mouse_process(int button, int state, int x, int y)
{
    mouseX = x;
    mouseY = y;
    if (button == GLUT_LEFT_BUTTON)
    {
        if (state == GLUT_DOWN)
        {
            mouseLeftDown = true;
        }
        else if (state == GLUT_UP)
            mouseLeftDown = false;
    }

    else if (button == GLUT_RIGHT_BUTTON)
    {
        if (state == GLUT_DOWN)
        {
            mouseRightDown = true;
        }
        else if (state == GLUT_UP)
            mouseRightDown = false;
    }


    
    // ==================================判断选中=========================================================
    // 三角形以外接圆为范围,圆以半径为范围
    float Y = -10.0 * (x- 0.5 * glutGet(GLUT_WINDOW_WIDTH)) / 3.0 / glutGet(GLUT_WINDOW_WIDTH);
    float X = -10.0 * (y - 0.5 * glutGet(GLUT_WINDOW_HEIGHT)) / 3.0 / glutGet(GLUT_INIT_WINDOW_HEIGHT);
    float mouseToTriangle = (triangleBiasX - X) * (triangleBiasX - X) + (triangleBiasY - Y) * (triangleBiasY - Y);
    float mouseToCircle = (circleBiasX - X) * (circleBiasX - X) + (circleBiasY - Y) * (circleBiasY - Y);
    if (mouseToTriangle < 0.25 && mouseToCircle < 0.11)selected = 1;
    else if (mouseToTriangle < 0.25)selected = 1;
    else if (mouseToCircle < 0.11)selected = 2;
    else selected = 0;
    // ===================================================================================================

}

void mouse_process_active(int x, int y)
{
  
    if (mouseLeftDown){// 进行平移，为了实现鼠标追踪，需要在窗口坐标系和世界坐标系之间进行转换
        //==================================移动========================================
        if (selected==1) {
             triangleBiasY -= 3*((float)x - mouseX)/ glutGet(GLUT_WINDOW_WIDTH);
             triangleBiasX -= 3*((float)y - mouseY)/ glutGet(GLUT_WINDOW_HEIGHT);
             //printf("(%.2f ,%.2f)", triangleBiasX, triangleBiasY);
        }
        else if (selected == 2) {
            circleBiasY -= 3 * ((float)x - mouseX) / glutGet(GLUT_WINDOW_WIDTH);
            circleBiasX -= 3 * ((float)y - mouseY) / glutGet(GLUT_WINDOW_HEIGHT);
            //printf("(% .2f, % .2f)", circleBiasX, circleBiasY);
        }

        mouseX = x;
        mouseY = y;
        //printf("(%d,%d)", x, y);// 检查屏幕坐标系的分布情况
        // ============================================================================
    }
    if(mouseRightDown)
    {   // 实时改变被选中图形的旋转积分量
        //============================旋转、翻转=======================================
        if (selected == 1) {
            triangleAngleY += (y - mouseY) * 0.2f;
            triangleAngleX += (x - mouseX) * 0.2f;
        }
        else if (selected == 2) {
            CircleAngleY += (y - mouseY) * 0.2f;
            CircleAngleX += (x - mouseX) * 0.2f;
        }
        // ============================================================================
        mouseX = x;
        mouseY = y;
    }

    glutPostRedisplay();

}
void mouse_process_passtive(int x, int y) {}


int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
    glutInitWindowSize(512, 512);
    glutCreateWindow("右键旋转 左键平移 Q退出");

    init();

    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    // later Edition
    glutMouseFunc(mouse_process);
    glutMotionFunc(mouse_process_active);
    glutPassiveMotionFunc(mouse_process_passtive);


    glutKeyboardFunc(keyboard);
    glutMainLoop();

    return 0;
}