1.繪制目標

建模并顯示下圖所示的立方體，要能回應鍵盤操作以旋轉該立方體：
‘x’:繞x軸旋轉
‘y’:繞y軸旋轉
‘z’:繞z軸旋轉
‘r’:復原

2.核心代碼

/**********************自定義變數**********************/
cv::Mat img[6];
int Pw = 0, Ph = 0;
const string picture[] = {
	"side1.png",
	"side2.png",
	"side3.png",
	"side4.png",
	"side5.png",
	"side6.png",
};
/******************************************************/

void loadTexture() {
	/// TO DO 
	///加載立方體六個面的紋理并設定紋理屬性//

	for (int i = 0; i < 6; i++)
	{
		img[i] = loadImage(picture[i], Pw, Ph);
	}

	// 設定紋理屬性
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_REPEAT);

	// 設定線形濾波
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
}

void init()
{
	glClearColor(0.f, 0.f, 0.f, 0.f);
	glEnable(GL_DEPTH_TEST);//開啟深度測驗

	/ TO DO /
	//申請紋理ID、加載紋理、設定紋理環境/
	// 申請紋理ID
	glGenTextures(6, TEXTURE_IDS);

	// 加載紋理
	loadTexture();

	// 設定紋理環境
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

	// 開啟紋理映射
	glEnable(GL_TEXTURE_2D);
}

void drawCube()
{
	/// TO DO 
	// 繪制立方體/
	//需要設計立方體六個面的三維頂點以及對應的紋理坐標///
	glBindTexture(GL_TEXTURE_CUBE_MAP, TEXTURE_IDS[0]);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, Pw, Ph, 0, GL_RGB, GL_UNSIGNED_BYTE, img[0].data);
	glBegin(GL_TRIANGLE_FAN);
	glTexCoord2f(0.f, 1.f); glVertex3f(-50, 50, 50);
	glTexCoord2f(0.f, 0.f); glVertex3f(-50, -50, 50);
	glTexCoord2f(1.f, 0.f); glVertex3f(50, -50, 50);
	glTexCoord2f(1.f, 1.f); glVertex3f(50, 50, 50);
	glEnd();

	glBindTexture(GL_TEXTURE_CUBE_MAP, TEXTURE_IDS[1]);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, Pw, Ph, 0, GL_RGB, GL_UNSIGNED_BYTE, img[1].data);
	glBegin(GL_TRIANGLE_FAN);
	glTexCoord2f(0.f, 1.f); glVertex3f(-50, -50, 50);
	glTexCoord2f(0.f, 0.f); glVertex3f(-50, -50, -50);
	glTexCoord2f(1.f, 0.f); glVertex3f(50, -50, -50);
	glTexCoord2f(1.f, 1.f); glVertex3f(50, -50, 50);
	glEnd();

	glBindTexture(GL_TEXTURE_CUBE_MAP, TEXTURE_IDS[2]);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, Pw, Ph, 0, GL_RGB, GL_UNSIGNED_BYTE, img[2].data);
	glBegin(GL_TRIANGLE_FAN);
	glTexCoord2f(0.f, 1.f); glVertex3f(-50, 50, -50);
	glTexCoord2f(0.f, 0.f); glVertex3f(-50, -50, -50);
	glTexCoord2f(1.f, 0.f); glVertex3f(-50, -50, 50);
	glTexCoord2f(1.f, 1.f); glVertex3f(-50, 50, 50);
	glEnd();

	glBindTexture(GL_TEXTURE_CUBE_MAP, TEXTURE_IDS[3]);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, Pw, Ph, 0, GL_RGB, GL_UNSIGNED_BYTE, img[3].data);
	glBegin(GL_TRIANGLE_FAN);
	glTexCoord2f(0.f, 1.f); glVertex3f(-50, -50, -50);
	glTexCoord2f(0.f, 0.f); glVertex3f(-50, 50, -50);
	glTexCoord2f(1.f, 0.f); glVertex3f(50, 50, -50);
	glTexCoord2f(1.f, 1.f); glVertex3f(50, -50, -50);
	glEnd();

	glBindTexture(GL_TEXTURE_CUBE_MAP, TEXTURE_IDS[4]);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, Pw, Ph, 0, GL_RGB, GL_UNSIGNED_BYTE, img[4].data);
	glBegin(GL_TRIANGLE_FAN);
	glTexCoord2f(0.f, 1.f); glVertex3f(-50, 50, -50);
	glTexCoord2f(0.f, 0.f); glVertex3f(-50, 50, 50);
	glTexCoord2f(1.f, 0.f); glVertex3f(50, 50, 50);
	glTexCoord2f(1.f, 1.f); glVertex3f(50, 50, -50);
	glEnd();

	glBindTexture(GL_TEXTURE_CUBE_MAP, TEXTURE_IDS[5]);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, Pw, Ph, 0, GL_RGB, GL_UNSIGNED_BYTE, img[5].data);
	glBegin(GL_TRIANGLE_FAN);
	glTexCoord2f(0.f, 1.f); glVertex3f(50, 50, 50);
	glTexCoord2f(0.f, 0.f); glVertex3f(50, -50, 50);
	glTexCoord2f(1.f, 0.f); glVertex3f(50, -50, -50);
	glTexCoord2f(1.f, 1.f); glVertex3f(50, 50, -50);
	glEnd();
}

void display()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();

	 TO DO /
	/ 設定模型、視點變換以及立方體顯示 /
	gluLookAt(0.0, 0.0, 260.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

	glRotatef(ZROT, 0.0f, 0.0f, 1.0f);
	glRotatef(YROT, 0.0f, 1.0f, 0.0f);
	glRotatef(XROT, 1.0f, 0.0f, 0.0f);

	glScalef(1, 1, 1);

	drawCube();

	glutSwapBuffers();
	glFlush();
}

void reshape(int w, int h)
{
	glViewport(0, 0, w, h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	// TO DO /
	 設定三維透視投影/
	gluPerspective(60, float(w) / float(h), 10.0, 1000.0);
}

// 鍵盤按鍵回掉函式
void keyboard(unsigned char key, int x, int y) {
	switch (key) {
	case 'x':
		/ TO DO /
		//設定繞x軸的旋轉角度
		XROT += 1.0f;

		glutPostRedisplay(); //更新顯示內容
		break;
	case 'y':
		/ TO DO /
		//設定繞y軸的旋轉角度
		YROT += 1.0f;

		glutPostRedisplay();
		break;
	case 'z':
		/ TO DO /
		//設定繞z軸的旋轉角度
		ZROT += 1.0f;

		glutPostRedisplay();
		break;
	case 'r':
		/ TO DO /
		//復原所有旋轉角度///
		XROT = 0.0f;
		YROT = 0.0f;
		ZROT = 0.0f;

		glutPostRedisplay();
	default:
		break;
	}
}

3.運行結果