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像真正的风力涡轮机一样旋转对象

coordinate-transformation glut opengl c++

4

Muddy · 技术社区 · 6 年前

#include <stdio.h>
#include <math.h>
#include "glut.h"

void init() {
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    gluOrtho2D(0.0, 400, 0.0, 300.0);
}

void drawTurbine() {
    // draw the tower
    glBegin(GL_LINES);
    glColor3f(1.0, 1.0, 1.0);
    glVertex2f(160, 40);
    glVertex2f(163, 180);
    glVertex2f(160, 40);
    glVertex2f(175, 40); 
    glVertex2f(175, 40);
    glVertex2f(172, 180);
    glEnd();
    // Rotate object
    glPushMatrix();
    glRotatef(100, 0, 1, 0);
    // draw first rotor blade
    glBegin(GL_TRIANGLES);
    glColor3f(1.0, 1.0, 1.0);
    glVertex2f(173, 180);
    glVertex2f(163, 180);
    glVertex2f(168, 270);
    glEnd();
    // draw second rotor blade
    glBegin(GL_TRIANGLES);
    glColor3f(1.0, 1.0, 1.0);
    glVertex2f(170, 174);
    glVertex2f(175, 180);
    glVertex2f(247, 140);
    glEnd();
    // draw third rotor blade
    glBegin(GL_TRIANGLES);
    glColor3f(1.0, 1.0, 1.0);
    glVertex2f(162, 180);
    glVertex2f(167, 174);
    glVertex2f(88, 140);
    glEnd();
    // circle in the middle
    float theta;
    glBegin(GL_POLYGON);
    glColor3f(1.0, 1.0, 1.0);
    for (int i = 0; i <= 360; i++) {
           theta = i * 3.142 / 180;
           glVertex2f(168 + 7 * cos(theta), 180 + 6.5 * sin(theta));
    }
    glEnd();
    glPopMatrix();
}

void display() {
    glClear(GL_COLOR_BUFFER_BIT);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    drawTurbine();
    glFlush();
    glutSwapBuffers();
    glutPostRedisplay();
}

void idle() {
    display();
}

int main(int argc, char** argv) {
    glutInit(&argc, argv); 
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(700, 600);
    glutInitWindowPosition(10, 10); 
    glutCreateWindow("Wind Turbine");
    init(); 
    glutIdleFunc(idle);
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}

1 回复 | 直到 5 年前

1

3

Rabbid76 6 年前

您需要一个用于风力涡轮机当前角度的变量( current_angle step_angle center_x , center_y

float current_angle = 0.0f;
float step_angle = 0.2f;
float center_x = 168.0f;
float center_y = 180.0f;

若要围绕轴旋转,必须定义模型矩阵,该矩阵通过反转轴置换,然后旋转并最终变换回轴。旋转轴是z轴(0,0,1),因为几何图形是在xy平面中绘制的:

glTranslatef( center_x, center_y, 0.0f );
glRotatef(current_angle, 0, 0, 1);
current_angle += step_angle;
glTranslatef(-center_x, -center_y, 0.0f );

预览:

函数的完整代码 drawTurbine

void drawTurbine() {
    // draw the tower
    glBegin(GL_LINES);
    glColor3f(1.0, 1.0, 1.0);
    glVertex2f(160, 40);
    glVertex2f(163, 180);
    glVertex2f(160, 40);
    glVertex2f(175, 40); 
    glVertex2f(175, 40);
    glVertex2f(172, 180);
    glEnd();
    // Rotate object
    glPushMatrix();

    glTranslatef( center_x, center_y, 0.0f );
    glRotatef(current_angle, 0, 0, 1);
    current_angle += step_angle;
    glTranslatef(-center_x, -center_y, 0.0f );

    // draw first rotor blade
    glBegin(GL_TRIANGLES);
    glColor3f(1.0, 1.0, 1.0);
    glVertex2f(173, 180);
    glVertex2f(163, 180);
    glVertex2f(168, 270);
    glEnd();
    // draw second rotor blade
    glBegin(GL_TRIANGLES);
    glColor3f(1.0, 1.0, 1.0);
    glVertex2f(170, 174);
    glVertex2f(175, 180);
    glVertex2f(247, 140);
    glEnd();
    // draw third rotor blade
    glBegin(GL_TRIANGLES);
    glColor3f(1.0, 1.0, 1.0);
    glVertex2f(162, 180);
    glVertex2f(167, 174);
    glVertex2f(88, 140);
    glEnd();
    // circle in the middle
    float theta;
    glBegin(GL_POLYGON);
    glColor3f(1.0, 1.0, 1.0);
    for (int i = 0; i <= 360; i++) {
           theta = i * 3.142 / 180;
           glVertex2f(168 + 7 * cos(theta), 180 + 6.5 * sin(theta));
    }
    glEnd();
    glPopMatrix();
}