Week04 林憶蓮的上課筆記

hw1:

(1)開啟小葉老師的網站>試試看車子能旋轉(Rotate) 、移動(Translate) 、縮放(Scale)

(2)開啟Glut專案>試試茶壺  移動(Translate)

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#include <GL/glut.h>
void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix();       ///backup the matrix
        glTranslatef(0.5,0,0);      ///Today's Most Important line
        glutSolidTeapot(0.3);
    glPopMatrix();     ///restore the matrix
    glutSwapBuffers();
}
int main (int argc,char ** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutCreateWindow("04160355 Translate Rotate Scale");

    glutDisplayFunc(display);
    ///glutMouseFunc(mouse);
    ///glutMotionFunc(motion);
    glutMainLoop();
}

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(3)加 motion >茶壺能跟著游標點擊來移動

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#include <GL/glut.h>
float mouseX=0,mouseY=0;
void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix();   ///backup the matrix
        glTranslatef(mouseX,mouseY,0); ///Today's Most Important line
        glutSolidTeapot(0.3);
    glPopMatrix(); ///restore the matrix
    glutSwapBuffers();
}

void motion(int x,int y)
{
    mouseX = (x-150)/150.0;
    mouseY = -(y-150)/150.0;
    glutPostRedisplay();
}

int main (int argc,char ** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutCreateWindow("04160355 Translate Rotate Scale");

    glutDisplayFunc(display);
    ///glutMouseFunc(mouse);
    glutMotionFunc(motion);
    glutMainLoop();
}

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↓↓老師截圖講解座標系統不同問題

(4)黃色小精靈會開口

• display() 裡的 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) 會把畫面清空,才能再重畫的時候沒有殘影
• display() 裡的 glutSwapBuffers() 會更新畫面/交換繪圖的 memory buffer
• motion() 裡的 glutPostRedisplay() 會貼個 3M Post便利貼,告訴GLUT要重畫畫面 Re-display
• for(float angle=0 +mouth; angle< 3.1415926 *2 -mouth; angle++) 可以讓 angle 的開始&結束的角度
• for(float angle=0; angle< 3.1415926 *2; angle++) 可以讓 angle從0到 2*PI
• float mouth=0 表示嘴巴張開的角度
• void motion(int x, int y) 可以把現在的mouth位置做改變
• glutMotionFunc(motion) 可以註冊 motion的函式

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#include <GL/glut.h>
#include <math.h>
float mouth=0;
void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glColor3f(1,1,0);
    glBegin(GL_TRIANGLE_FAN);
        glVertex2f(0,0);
        for(float angle=0+mouth; angle<= 3.1415926 *2-mouth; angle+=0.01)
        {
            glVertex2f(cos(angle),sin(angle));
        }
        glEnd();
    glutSwapBuffers();
}

void motion(int x,int y)
{
   mouth = x/300.0;
    glutPostRedisplay();
}
int main (int argc,char ** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutCreateWindow("04160355 Translate Rotate Scale");

    glutDisplayFunc(display);
    ///glutMouseFunc(mouse);
    glutMotionFunc(motion);
    glutMainLoop();
}

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(5)茶壺能夠旋轉 (Rotate) 、放大(Scale)

• glScalef()的參數是 x,y,z 分別表示3個方向的縮放比例
• glScalef() 開頭的 gl表示是 OpenGL的函式
• glScalef() 結尾的f表示是float的參數
• glScalef(0,0,0) 會讓東西變不見
• glScalef(-1,-1, -1) 會讓東西的上下反過來, 左右反過來

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#include <GL/glut.h>
float mouseX=0,mouseY=0;
void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix();   ///backup the matrix
        glScalef(mouseX,mouseY,0); ///Today's Most Important line
        glutSolidTeapot(0.3);
    glPopMatrix(); ///restore the matrix
    glutSwapBuffers();
}

void motion(int x,int y)
{
    mouseX = (x-150)/150.0;
    mouseY = -(y-150)/150.0;
    glutPostRedisplay();
}
int main (int argc,char ** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutCreateWindow("04160355 Translate Rotate Scale");

    glutDisplayFunc(display);
    ///glutMouseFunc(mouse);
    glutMotionFunc(motion);
    glutMainLoop();
}

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