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#pragma comment(linker, "/SUBSYSTEM:WINDOWS /ENTRY:mainCRTStartup")
#include <GL/freeglut/freeglut.h>
#include <math.h>
#define PI 3.1415926
#define WIDTH 320
#define HEIGHT 240
//平行移動用
float x = 0.0f;
bool flag = false;
//緑
GLfloat green[] = { 0.0, 1.0, 0.0, 1.0 };
//ライトの位置
GLfloat lightpos[] = { 200.0, 150.0, -500.0, 1.0 };
//単位行列
GLfloat mat[]={
1,0,0,0,
0,1,0,0,
0,0,1,0,
0,0,0,1
};
//平行移動用
GLfloat move[]={
1,0,0,0,
0,1,0,0,
0,0,1,0,
0,0,0,1
};
GLfloat modelview[16];
GLfloat multi[16];
//合成 glMultMatrixfの代わり
void multiplication(GLfloat* src1,GLfloat* src2,GLfloat* dst)
{
for(int y=0;y<4;y++){
for(int x=0;x<4;x++){
dst[y*4+x]=src2[y*4]*src1[x]+src2[y*4+1]*src1[x+4]+src2[y*4+2]*src1[x+8]+src2[y*4+3]*src1[x+12];
}
}
}
//正規化
void normalize(GLfloat* v){
float m=sqrt(v[0]*v[0]+v[1]*v[1]+v[2]*v[2]);
if(m > 0.0f){m = 1.0f / m;}else{m = 0.0f;}
v[0]*=m;
v[1]*=m;
v[2]*=m;
}
//外積
void cross( float* src1, float* src2 ,float* dst){
dst[0] = src1[1]*src2[2] - src1[2]*src2[1];
dst[1] = src1[2]*src2[0] - src1[0]*src2[2];
dst[2] = src1[0]*src2[1] - src1[1]*src2[0];
}
//gluLookAtと同じ
void LookAt(GLfloat eyex, GLfloat eyey, GLfloat eyez, GLfloat centerx,
GLfloat centery, GLfloat centerz, GLfloat upx, GLfloat upy,
GLfloat upz)
{
float forward[3], side[3], up[3];
forward[0] = centerx - eyex;
forward[1] = centery - eyey;
forward[2] = centerz - eyez;
up[0] = upx;
up[1] = upy;
up[2] = upz;
normalize(forward);
cross(forward, up, side);
normalize(side);
cross(side, forward, up);
GLfloat m[]={
side[0],up[0],-forward[0],0,
side[1],up[1],-forward[1],0,
side[2],up[2],-forward[2],0,
0,0,0,1
};
GLfloat mov[]={
1,0,0,0,
0,1,0,0,
0,0,1,0,
-eyex,-eyey,-eyez,1
};
multiplication(m,mov,multi);
glLoadMatrixf(multi);
}
//gluPerspectiveと同じ
void perspective(float fovy,float aspect,float znear,float zfar)
{
float radian=2*PI*fovy/360.0;
float t = (float)(1.0 / tan(radian/2));
GLfloat m[]={
t / aspect,0,0,0,
0,t,0,0,
0,0,(zfar + znear) / (znear - zfar),-1,
0,0,(2 * zfar * znear) / (znear - zfar),0
};
glLoadMatrixf(m);
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glViewport(0, 0, WIDTH, HEIGHT);
glMatrixMode(GL_PROJECTION);
//glLoadIdentity();と同じ↓
glLoadMatrixf(mat);
//視野角,アスペクト比(ウィンドウの幅/高さ),描画する範囲(最も近い距離,最も遠い距離)
//gluPerspective(30.0, (double)WIDTH / (double)HEIGHT, 1.0, 1000.0);と同じ↓
perspective(30.0, (double)WIDTH / (double)HEIGHT, 1.0, 1000.0);
glMatrixMode(GL_MODELVIEW);
//glLoadIdentity();と同じ↓
glLoadMatrixf(mat);
//視点の設定
//gluLookAt(150.0,100.0,-200.0,0.0,0.0,0.0,0.0,1.0,0.0);と同じ↓
LookAt(150.0,100.0,-200.0, //カメラの座標
0.0,0.0,0.0, // 注視点の座標
0.0,1.0,0.0); // 画面の上方向を指すベクトル
//ライトの設定
glLightfv(GL_LIGHT0, GL_POSITION, lightpos);
//マテリアルの設定
glMaterialfv(GL_FRONT, GL_DIFFUSE, green);
//平行移動
//glTranslatef(x,0.0f,0.0f);と同じ↓
move[12]=x; //X軸の平行移動成分を設定
//glMultMatrixf(move);と同じ↓
glGetFloatv(GL_MODELVIEW_MATRIX,modelview);
multiplication(modelview,move,multi);
glLoadMatrixf(multi);
glutSolidSphere(40.0,16,16);
glutSwapBuffers();
}
void idle(void)
{
if(flag){x-=1.0f;}else{x+=1.0f;}
if(x>50.0f)flag=true;
if(x<-50.0f)flag=false;
Sleep(1);
glutPostRedisplay();
}
void Init(){
glClearColor(0.3f, 0.3f, 0.3f, 1.0f);
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
}
int main(int argc, char *argv[])
{
glutInitWindowPosition(100, 100);
glutInitWindowSize(WIDTH, HEIGHT);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
glutCreateWindow("gluLookAtを置き換える");
glutDisplayFunc(display);
glutIdleFunc(idle);
Init();
glutMainLoop();
return 0;
}
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