STEP 01
1.到https://jsyeh.org/3dcg10/下載data/win32，並解壓縮
2.執行projection.exe，試了解gluLookAt，我們看到三個東西都各有三個參數，分別是eye,center,up
3.透過調整數字，我們大致明白eye是從哪裡看，center是看哪裡
STEP 02
1.up是關於從eye到center，他們之間會形成一個軸線，up會以該軸線作旋轉軸，以360度為限(一圈)，跟攝影機直拍橫拍反著拍有關係，偶爾斜拍，up向量也會向著斜斜的方向
STEP 03
1.上面還有一行程式碼，gluPerspective，他有四個參數值，第一個是fovy，是視野的角度，或許是類似廣角鏡頭的效果，第二個是aspect是長寬比，預設是1，也就是1:1，如果調整成2，那就是2:1，第三個和第四個zNear，zFar，是指視線的最近範圍和最遠範圍
STEP 04
1.用git指令把程式倉庫複製到桌面
2.開啟一個新專案，我們直接建立在程式倉庫裡，並直接使用裡面的freeglut
3.在預設的程式碼加上程式碼，如圖:
STEP 05
1.建立另一個新專案
2.打上程式碼:
#include <GL/glut.h>
void display()
{
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glutSolidTeapot(0.3);
glutSwapBuffers();
}
void reshape(int w, int h){
glViewport(0, 0, w, h);///視窗裡會看到的2D範圍
float ar = w / (float) h;///長寬比
glMatrixMode(GL_PROJECTION);///切換成投影矩陣
glLoadIdentity();///矩陣清空，還原成單位矩陣
gluPerspective(60, ar, 0.01, 1000);
glMatrixMode(GL_MODELVIEW);///切換成MODEL VIEW矩陣
glLoadIdentity();///還原成單位矩陣
gluLookAt(0,0,1, 0,0,0, 0,1,0);
glutPostRedisplay();
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH);
glutCreateWindow("Week15");
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();
}
我們從很近的位置看茶壺，茶壺看起來比較大:
STEP 06
1.我們增加motion函式，令其可以藉由滑鼠調整鏡頭觀看的角度，圖以右上看茶壺為例
STEP07
1.打開final_project
2.將角度改為陣列，程式碼如下:
#include <stdio.h>
#include <GL/glut.h>
#include "glm.h"
GLMmodel * head = NULL;
GLMmodel * body = NULL;
GLMmodel * uparmR = NULL;
GLMmodel * lowarmR = NULL;
int show[4] = {0, 1, 1, 1};
int ID=3;//0頭1身2上手臂3下手臂
void keyboard(unsigned char key, int x, int y){
if(key=='0') ID=0;
if(key=='1') ID=1;
if(key=='2') ID=2;
if(key=='3') ID=3;
///if(key=='0') show[0] = !show[0];
///if(key=='1') show[1] = !show[1];
///if(key=='2') show[2] = !show[2];
///if(key=='3') show[3] = !show[3];
glutPostRedisplay();
}
FILE * fout = NULL;
FILE * fin = NULL;
float teapotX=0, teapotY=0;
float angle[20]={};
void display()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glScalef(0.2, 0.2, 0.2);
if(body==NULL){
body = glmReadOBJ("model/body.obj");
head = glmReadOBJ("model/head.obj");
uparmR = glmReadOBJ("model/uparmR.obj");
lowarmR = glmReadOBJ("model/lowarmR.obj");
//glmUnitize(body);
}
if(ID==0) glColor3f(1,0,0);
else glColor3f(1,1,1);
if(show[0]) glmDraw(head, GLM_MATERIAL);
if(ID==1) glColor3f(1,0,0);
else glColor3f(1,1,1);
if(show[1]) glmDraw(body, GLM_MATERIAL);
glPushMatrix();
glTranslatef(-1.186666, +0.380000, 0);
glRotatef(angle[2], 0, 0, 1);
glTranslatef(1.186666, -0.380000, 0);
if(ID==2) glColor3f(1,0,0);
else glColor3f(1,1,1);
if(show[2]) glmDraw(uparmR, GLM_MATERIAL);
glPushMatrix();
//glTranslatef(teapotX, teapotY, 0);
glTranslatef(-1.953333, +0.120001, 0);
glRotatef(angle[3], 0, 0, 1);
glTranslatef(1.953333, -0.120001, 0);
if(ID==3) glColor3f(1,0,0);
else glColor3f(1,1,1);
if(show[3]) glmDraw(lowarmR, GLM_MATERIAL);
glPopMatrix();
glPopMatrix();
glPopMatrix();
glColor3f(0,1,0);
glutSolidTeapot(0.02);
glutSwapBuffers();
}
int oldX = 0, oldY = 0;
void motion(int x, int y){
teapotX += (x - oldX)/150.0;
teapotY -= (y - oldY)/150.0;
angle[ID] += (x-oldX);
oldX = x;
oldY = y;
printf("glTranslatef(%f, %f, 0);\n", teapotX, teapotY);
glutPostRedisplay();
}
void mouse(int button, int state, int x, int y)
{
if(state==GLUT_DOWN){
oldX = x;
oldY = y;
teapotX = (x-150)/150.0;
teapotY = (150-y)/150.0;
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)
//{
// if(fin==NULL){
// fclose(fout);
// fin = fopen("file4.txt","r");
// }
// fscanf(fin, "%f %f", &teapotX, &teapotY);
// display();
//}
int main(int argc, char *argv[])//main()主函式 進階版
{
glutInit(&argc,argv);//把參數送給glutInit初始化
glutInitDisplayMode(GLUT_DOUBLE|GLUT_DEPTH);//雙緩衝區+3D深度功能
glutCreateWindow("week15");//開GLUT視窗
glutDisplayFunc(display);//顯示用的函式
glutMouseFunc(mouse);
glutMotionFunc(motion);
glutKeyboardFunc(keyboard);
glutMainLoop();
}
就能夠轉動選擇的位置
3.想用開檔案的方式作簡易的動畫，於是將程式碼改成這樣:
#include <stdio.h>
#include <GL/glut.h>
#include "glm.h"
GLMmodel * head = NULL;
GLMmodel * body = NULL;
GLMmodel * uparmR = NULL;
GLMmodel * lowarmR = NULL;
int show[4] = {0, 1, 1, 1};
int ID=3;//0頭1身2上手臂3下手臂
FILE * fout = NULL;
FILE * fin = NULL;
float teapotX=0, teapotY=0;
float angle[20]={};
void keyboard(unsigned char key, int x, int y){
if(key=='0') ID=0;
if(key=='1') ID=1;
if(key=='2') ID=2;
if(key=='3') ID=3;
if(key=='s'){
if(fout==NULL) fout = fopen("motion.txt", "w");
for(int i=0;i<20;i++){
fprintf(fout, "%.2f ", angle[i] );
}
fprintf(fout, "\n");
}else if(key=='r'){
if(fin==NULL) fin = fopen("motion.txt", "r");
for(int i=0;i<20;i++){
fscanf(fin, "%f", &angle[i] );
}
glutPostRedisplay();
}
///if(key=='0') show[0] = !show[0];
///if(key=='1') show[1] = !show[1];
///if(key=='2') show[2] = !show[2];
///if(key=='3') show[3] = !show[3];
glutPostRedisplay();
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glScalef(0.2, 0.2, 0.2);
if(body==NULL){
body = glmReadOBJ("model/body.obj");
head = glmReadOBJ("model/head.obj");
uparmR = glmReadOBJ("model/uparmR.obj");
lowarmR = glmReadOBJ("model/lowarmR.obj");
//glmUnitize(body);
}
if(ID==0) glColor3f(1,0,0);
else glColor3f(1,1,1);
if(show[0]) glmDraw(head, GLM_MATERIAL);
if(ID==1) glColor3f(1,0,0);
else glColor3f(1,1,1);
if(show[1]) glmDraw(body, GLM_MATERIAL);
glPushMatrix();
glTranslatef(-1.186666, +0.380000, 0);
glRotatef(angle[2], 0, 0, 1);
glTranslatef(1.186666, -0.380000, 0);
if(ID==2) glColor3f(1,0,0);
else glColor3f(1,1,1);
if(show[2]) glmDraw(uparmR, GLM_MATERIAL);
glPushMatrix();
//glTranslatef(teapotX, teapotY, 0);
glTranslatef(-1.953333, +0.120001, 0);
glRotatef(angle[3], 0, 0, 1);
glTranslatef(1.953333, -0.120001, 0);
if(ID==3) glColor3f(1,0,0);
else glColor3f(1,1,1);
if(show[3]) glmDraw(lowarmR, GLM_MATERIAL);
glPopMatrix();
glPopMatrix();
glPopMatrix();
glColor3f(0,1,0);
glutSolidTeapot(0.02);
glutSwapBuffers();
}
int oldX = 0, oldY = 0;
void motion(int x, int y){
teapotX += (x - oldX)/150.0;
teapotY -= (y - oldY)/150.0;
angle[ID] += (x-oldX);
oldX = x;
oldY = y;
printf("glTranslatef(%f, %f, 0);\n", teapotX, teapotY);
glutPostRedisplay();
}
void mouse(int button, int state, int x, int y)
{
if(state==GLUT_DOWN){
oldX = x;
oldY = y;
teapotX = (x-150)/150.0;
teapotY = (150-y)/150.0;
//if(fout==NULL) fout = fopen("file4.txt","w");注:只能有一個開檔案，不然會出錯，這裡註解掉
//fprintf(fout, "%f %f\n", teapotX, teapotY);
}
display();
}
//void keyboard(unsigned char key,int x, int y)
//{
// if(fin==NULL){
// fclose(fout);
// fin = fopen("file4.txt","r");
// }
// fscanf(fin, "%f %f", &teapotX, &teapotY);
// display();
//}
int main(int argc, char *argv[])//main()主函式 進階版
{
glutInit(&argc,argv);//把參數送給glutInit初始化
glutInitDisplayMode(GLUT_DOUBLE|GLUT_DEPTH);//雙緩衝區+3D深度功能
glutCreateWindow("week15");//開GLUT視窗
glutDisplayFunc(display);//顯示用的函式
glutMouseFunc(mouse);
glutMotionFunc(motion);
glutKeyboardFunc(keyboard);
glutMainLoop();
}
按S能存檔案，R可以讀檔案
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