10160305賴奕廷Week02

week02

前置作業:

將上週freeglut應用的GLUT打開

*step01:做茶壺

#include <GL/glut.h>
void display()
{
    glutSolidTeapot(0.3);
    glutSwapBuffers();  //交換顯示
}
int main(int argc, char *argv[])
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);  //設定顯示模式
    glutCreateWindow("week02");  //視窗名稱
    glutDisplayFunc(display);  //顯示的函式
    glutMainLoop();  //主要迴圈最後
}

*step02:把茶壺弄上顏色

#include <GL/glut.h>

void display()

{

    glColor3f(1,1,1);  //選擇顏色

    glutSolidTeapot(0.3);  //實心茶壺

    glColor3f(1,0,0.6);  //粉色

    glutSolidTeapot(0.2);

    glutSwapBuffers();

}

int main(int argc, char *argv[])

{

    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);

    glutCreateWindow("week02");

    glutDisplayFunc(display);

    glutMainLoop();

}

*step03:放一個三角形

#include <GL/glut.h>

void display()

{

    glColor3f(1,1,1);

    glBegin(GL_POLYGON);

        glVertex2f(0,1);  //上面頂點

        glVertex2f(-1,-1);  //左下角頂點

        glVertex2f(1,-1);  //右下角頂點

    glEnd();

    glColor3f(1,0,0.6);

    glutSolidTeapot(0.3);

    glutSwapBuffers();

}

int main(int argc, char *argv[])

{

    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);

    glutCreateWindow("week02");

    glutDisplayFunc(display);

    glutMainLoop();

}

*step04:加三角形的顏色

#include <GL/glut.h>

void display()

{

    glBegin(GL_POLYGON);

        glColor3f(1,1,1);   glVertex2f(0,1);

        glColor3f(0.5,0,0.5); glVertex2f(-1,-1);

        glColor3f(0.8,0,0.8);   glVertex2f(1,-1);

    glEnd();

    glColor3f(1,0,0.6);

    glutSolidTeapot(0.3);

    glutSwapBuffers();

}

int main(int argc, char *argv[])

{

    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);

    glutCreateWindow("week02");

    glutDisplayFunc(display);

    glutMainLoop();

}

*step05:用小畫家找圖的位置和顏色

頂點:

開200*200的畫布把找到的圖貼上去，滑鼠移動左下角有像素，左邊為X軸，右邊為Y軸

丟進程式時需先減一半，再除一半，且Y軸須為負

 0 ~ 200 => -100 ~ +100 => -1.0 ~ +1.0

例: glVertex2f ( (103-100) /100.0 ,  - (7-100) /100.0 ); 

顏色:

用滴管吸圖上的顏色，再點選編輯色彩，即可看到色碼

丟進程式時需除255.0  //不可以超過0 ~ 1

例: glColor3f ( 255/255.0 , 128/255.0 , 192/255.0 );

*step06:畫圓

#include <GL/glut.h>

#include <math.h>

void myCircle(float r, float x, float y)

{

    glBegin(GL_POLYGON);

    for(float a=0; a<=2*3.141592; a+=0.01)

    {

        glVertex2f( r*cos(a)+x, r*sin(a)+y);

    }

    glEnd();

}

void display()

{

    glColor3f(1,1,1);  //大圓

    myCircle(0.5,0,0);

    glColor3f(1,0,0.5);  //左上

    myCircle(0.3,-0.4,0.6);

    glColor3f(0.8,0,0.8);  //右下

    myCircle(0.3,0.4,-0.6);

    glutSwapBuffers();

}

int main(int argc, char *argv[])

{

    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);

    glutCreateWindow("week02");

    glutDisplayFunc(display);

    glutMainLoop();

}