2023電腦圖學二乙: 小葉老師一步步教圖學 Week12 檔案、鍵盤、滑鼠

Week12

step01-1

step01-1_新的空白檔案 week12-1_printf_fprintf.cpp 要練習寫檔案。和 printf()很像, fprintf()的前面, 要有一個 f 也就是檔案指標。檔案指標 fout = fopen("檔名", "w") 就會寫檔出去。

```cpp

///Week12-1_printf_fprintf.cpp

///要開檔案指標 fopen()

#include <stdio.h>

int main()

{///檔案指標 fout = fopen("檔名", "模式"); 要開檔

FILE * fout = fopen("file.txt", "w");///w:write

printf("Hello World\n");

fprintf(fout, "Hello World在檔案裡\n");

}

```

step01-2

step01-2_新的空白檔案 week12-2_fscanf.cpp 要把檔案讀進來, 檔案指標 fin = fopen("檔名", "r") 之後 fscanf()便能把 fin 當前面的參數來讀檔。前一個程式 fprintf()印出字串, 這裡就宣告字串 char line[20]; 再用 %s 讀進來。因為空格斷開, 所以分2次讀入。

```cpp

///Week12-2_scanf.cpp

#include <stdio.h>

int main()

{

char line[20];

///scanf("%s", line);

FILE * fin = fopen("file.txt", "r");///r:read讀

fscanf(fin, "%s", line);

printf("讀到了:%s\n", line);///馬上印

fscanf(fin, "%s", line);

printf("讀到了:%s\n", line);///馬上印

}

```

step01-3

step01-3_接下來就辛苦了, 我們想要在同一個程式中, 又有寫檔案、又有讀檔案。新的空白檔案 week12-3_fopen_fclose_fprintf_fscanf.cpp 在這個範例裡, 我們想寫的是一堆數字、想讀的也是一堆數字(因為期末作品,要做出動畫的動作時, 有很多關節的角度要存起來, 之後再播放)。因為是同一個檔案, 明顯會出問題, 一定要記得 fopen() 結束時要fclose()。

```cpp

///week12-3_fopen_fclose_fprintf_fscanf.cpp

#include <stdio.h>

int main()

{

int a[10] = {10,20,30,40,50,60,70,80,90,100};

FILE * fout = fopen("file3.txt", "w");

for(int i=0; i<10; i++){

fprintf(fout, "%d ", a[i] ); ///寫到檔案去,同時

printf("%d ", a[i] ); ///順便印出來,讓你看看

}

fclose(fout);

int b[10];

FILE * fin = fopen("file3.txt", "r");

for(int i=0; i<10; i++){

fscanf(fin, "%d", &b[i] ); ///讀到陣列 b[i]裡

printf("%d ", b[i] );

}

fclose(fin);

}

```

step02-0

step02-0_介紹buffer_overflow相關的議題,小心指標容易出錯

step02-1

step02-1_新的GLUT專案 week12-4_keyboard_mouse 想要用 mouse 來控制 teapot 的位置, 使用 teapotX 和 teapotY 變數, 再 glTranslatef(teapotX, teapotY, 0) 來移動茶壼。

```cpp

///Week12-4_keyboard_mouse 要能用 mouse來移動, 同時要解決存讀檔的問題

#include <stdio.h> ///要檔案的Input/Output

#include <GL/glut.h>

float teapotX = 0, teapotY = 0;

void display()

{

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

glPushMatrix();

glTranslatef(teapotX, teapotY, 0);

glutSolidTeapot( 0.3 );

glPopMatrix();

glutSwapBuffers();

}

void mouse(int button, int state, int x, int y)

{

teapotX = (x-150)/150.0;

teapotY = (150-y)/150.0;

display();

}

int main(int argc, char** argv)

{

glutInit(&argc, argv);

glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH);

glutCreateWindow("week12");

glutDisplayFunc(display);

glutMouseFunc(mouse); ///step02-1

glutMainLoop();

}

```

step02-2

step02-2_剛剛的 week12_keyboard_mouse專案裡, 還沒有加檔案的部分, 我們將在 mouse()裡的 GLUT_DOWN 按下mouse時寫檔, 再用 keyboard() 來觸發讀檔的動作。

```cpp

///Week12-4_keyboard_mouse 要能用 mouse來移動, 同時要解決存讀檔的問題

#include <stdio.h> ///要檔案的Input/Output

#include <GL/glut.h>

float teapotX = 0, teapotY = 0;

FILE * fout = NULL;///step02-1

FILE * fin = NULL;///step02-2

void display()

{

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

glPushMatrix();

glTranslatef(teapotX, teapotY, 0);

glutSolidTeapot( 0.3 );

glPopMatrix();

glutSwapBuffers();

}

void mouse(int button, int state, int x, int y)

{

teapotX = (x-150)/150.0;

teapotY = (150-y)/150.0;

if(state==GLUT_DOWN){ ///如果mouse按下去

if(fout==NULL) fout = fopen("file4.txt", "w");

fprintf(fout, "%f %f\n", teapotX, teapotY);

}

display();

}

void keyboard(unsigned char key, int x, int y)///step02-2

{

if(fin==NULL){

fclose(fout);///step02-2

fin = fopen("file4.txt", "r");///step02-2

}

fscanf(fin, "%f%f", &teapotX, &teapotY);///step02-2

display();///step02-2

}///step02-2

int main(int argc, char** argv)

{

glutInit(&argc, argv);

glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH);

glutCreateWindow("week12");

glutDisplayFunc(display);

glutKeyboardFunc(keyboard); ///step02-2

glutMouseFunc(mouse); ///step02-1

glutMainLoop();

}

```

step03-1

step03-1_再來調整工作執行目錄 CodeBlocks 的 Project-Properties 裡可改

```cpp

///Week12-4_keyboard_mouse 要能用 mouse來移動, 同時要解決存讀檔的問題

#include <stdio.h> ///要檔案的Input/Output

#include <GL/glut.h>

///step03-1

///CodeBlocks的專案設定 Project-Properties裡第二個Build Target

/// Executing working dir 工作執行目錄

///原本是 C:\Users\Administrator\Desktop\freeglut\bin

///改成 . (小數點) 再 File-Save Everything 便能將專案檔設好、存檔。

///之後你的工作執行目錄, 就在你的程式專案的那一目錄裡

///但執行時, 就會少了 freeglut.dll 檔, 你再手動copy到你的專案檔裡。

/// 註: 你可以看到 .cbp CodeBlocks Project 專案裡 working_dir 有變動哦

float teapotX = 0, teapotY = 0;

FILE * fout = NULL;///step02-1

FILE * fin = NULL;///step02-2

void display()

{

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

glPushMatrix();

glTranslatef(teapotX, teapotY, 0);

glutSolidTeapot( 0.3 );

glPopMatrix();

glutSwapBuffers();

}

void mouse(int button, int state, int x, int y)

{

teapotX = (x-150)/150.0;

teapotY = (150-y)/150.0;

if(state==GLUT_DOWN){ ///如果mouse按下去

if(fout==NULL) fout = fopen("file4.txt", "w");

fprintf(fout, "%f %f\n", teapotX, teapotY);

}

display();

}

void keyboard(unsigned char key, int x, int y)///step02-2

{

if(fin==NULL){

fclose(fout);///step02-2

fin = fopen("file4.txt", "r");///step02-2

}

fscanf(fin, "%f%f", &teapotX, &teapotY);///step02-2

display();///step02-2

}///step02-2

int main(int argc, char** argv)

{

glutInit(&argc, argv);

glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH);

glutCreateWindow("week12");

glutDisplayFunc(display);

glutKeyboardFunc(keyboard); ///step02-2

glutMouseFunc(mouse); ///step02-1

glutMainLoop();

}

step03-2

step03-2_想在同一個目錄裡, 寫期末作品Final_Project 所以,把CodeBlocks關掉(確認檔案都有存好),整個 week12-4_keyboard_mouse目錄,都copy 目錄改成 Final_Project, 把專案檔 week12-4_keyboard_mouse.cbp 改成 Final_Project.cbp。再把 Project-Properties裡的title改成 Final_Project, Save Everything。之後雲端這份, 到處都能用。只用這個來寫期末作品。