C++ LookAt函数代码示例

void display(void)
{

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
    glBindBuffer(GL_ARRAY_BUFFER,buffer);

    mv = LookAt( eye, eye - n, up );
    model_view = mv;

   // for(int i= -5; i<=5; i++)
     //   for(int j= -5; j<=5; ++j)
        {
           // model_view = mv * Translate(i*3.0f,j*3.0f, 0.0f);
            traverse(head);
        }
    glutSwapBuffers();
}

Camera::Camera(float theta, float phi, float radius)
	:
	mPos(XMFLOAT3(0.0f,0.0f,0.0f)),
	mTheta(theta),
	mPhi(phi),
	mRadius(radius),
	mLook(XMFLOAT3(0.0f, 0.0f, 1.0f)),
	mUp(XMFLOAT3(0.0f, 1.0f, 0.0f)),
	mRight(XMFLOAT3(1.0f, 0.0f, 0.0f))
{
	XMMATRIX I = XMMatrixIdentity();
	XMStoreFloat4x4(&mView, I);
	XMStoreFloat4x4(&mProj, I);

	LookAt(mPos, mLook, mUp);
	UpdateView();
}

//----------------------------------------------------------------------------
// The passive motion callback for a window is called when the mouse moves within the window while no mouse buttons are pressed.
void Win_PassiveMotion(int x, int y) {

	g_fPhi = (float)-M_PI*(x - HALF_SIZE)/(HALF_SIZE); // 轉換成 g_fPhi 介於 -PI 到 PI 之間 (-180 ~ 180 之間)
	g_fTheta = (float)M_PI*(float)y/SCREEN_SIZE;
	g_vEye.x = g_fRadius*sin(g_fTheta)*sin(g_fPhi);
	g_vEye.y = g_fRadius*cos(g_fTheta);
	g_vEye.z = g_fRadius*sin(g_fTheta)*cos(g_fPhi);

	g_mxModelView = LookAt( g_vEye, g_vAt, g_vUp );

	// Change ModelView Matrix
	g_pFloor->SetModelViewMatrix(g_mxModelView);
	g_pCube->SetModelViewMatrix(g_mxModelView);
	g_pSphere->SetModelViewMatrix(g_mxModelView);
	g_pLight->SetModelViewMatrix(g_mxModelView);

}

void SetupRC() {
	glClearColor(0.1f, 0.2f, 0.3f, 0.0f);
    shader = gltLoadShaderPairWithAttributes("pass_thru_shader.vp", "pass_thru_shader.fp",2, GLT_ATTRIBUTE_VERTEX, "vVertex", GLT_ATTRIBUTE_COLOR, "vColor");
    fprintf(stdout, "GLT_ATTRIBUTE_VERTEX : %d\nGLT_ATTRIBUTE_COLOR : %d \n",GLT_ATTRIBUTE_VERTEX, GLT_ATTRIBUTE_COLOR);

	MVPMatrixLocation = glGetUniformLocation(shader,"MVMatrix");
	if(MVPMatrixLocation==-1) {
		fprintf(stderr,"uniform MVMatrix could not be found\n");
	}

	M3DVector3f	eye = {0.0f, -0.3f, 2.0f};		//Ustawienia kamery
	M3DVector3f	at = {0.0f, 1.0f, -1.0f};
	M3DVector3f	up = {1.0f, 1.0f, 0.0f};

	LookAt(frame,eye,at,up);

}

void RenderScene(void) {
    // Clear the window with current clearing color
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

    glUseProgram(shader);
	glEnable(GL_CULL_FACE);
	glFrontFace(GL_CW);

	CStopWatch timer;
	float angle = timer.GetElapsedSeconds()*3.14f;

	M3DVector3f mAt={0,0,0};
	M3DVector3f mUp={0,0,1};
	M3DVector3f mEye;

	mEye[0]=6.8f*cos(angle);
	mEye[1]=6.0f*sin(angle);
	mEye[2]=5.0f; 
	LookAt(mFrame,mEye,mAt,mUp);
	mFrame.GetCameraMatrix(mCameraMatrix);

	matrixStack.LoadMatrix(mFrustrum.GetProjectionMatrix());
	matrixStack.MultMatrix(mCameraMatrix);

	glUniformMatrix4fv(MVPMatrixLocation, 1, GL_FALSE, matrixStack.GetMatrix());

	drawGrid();

	matrixStack.Translate(1.0f,7.0f,0.0f);
	matrixStack.Rotate(30.0f,0.0,0.0,1.0);
	glUniformMatrix4fv(MVPMatrixLocation,1,GL_FALSE,matrixStack.GetMatrix());
	drawPyramid();

	matrixStack.PopMatrix();
	matrixStack.Translate(-7.0f,0.0f,0.0f);
	matrixStack.Scale(2.0f, 2.0f, 2.0f);
	glUniformMatrix4fv(MVPMatrixLocation,1,GL_FALSE,matrixStack.GetMatrix());
	drawPyramid();

	matrixStack.PopMatrix();

	// Perform the buffer swap to display back buffer
    glutSwapBuffers();
	glutPostRedisplay();
}

	void DefenderManager::UpdateSpawning()
	{
		if(m_WaveTimer < 0.0f)
		{
			auto angleStep = 90.0f / (GSETTINGS->m_DefenderManagerSettings->m_SpotsPerQuarter + 1);
			for(int i=0; i<4; ++i)
			{
				auto angleStart = 90.0f*i;
				auto angleEnd = 90.0f*(i+1);
				for (int j = 0; j < GSETTINGS->m_DefenderManagerSettings->m_CountPerWavePerQuarter; ++j)
				{
					auto spawnAngle = angleStart + angleStep*(m_RandomSpots.GetNext()+1);
					auto spawnDir = Vector3::Create(Math::Cos(spawnAngle*Math::DegToRadFactor), Math::Sin(spawnAngle*Math::DegToRadFactor), 0.0f);
					auto pos = spawnDir * GSETTINGS->m_DefenderManagerSettings->m_Radius;
					auto range = GSETTINGS->m_DefenderManagerSettings->m_AngleRange;
					auto angle = Random::GetFloat(-range, range);
					auto dir = (-spawnDir).Rotate(Vector3::Up, angle * Math::DegToRadFactor);

					// Spawn actor
					auto newActor = static_cast<Defender*>(m_PreloadedActor->Copy());
					AddChild(newActor);
					newActor->SetPosition(pos);
					newActor->LookAt(dir);
					newActor->SwitchState(Defender::S_Hover);
					newActor->InitActor(GSETTINGS->m_DefenderSettings);
					m_lDefenders.push_back(newActor);
				}
			}

			m_WaveTimer = GSETTINGS->m_DefenderManagerSettings->m_WaveFrequency;
		}
		else
			m_WaveTimer -= g_fDeltaTime;

		if (m_SpawnTimer < 0.0f)
		{
			SwitchState(S_Defending);

			auto camera = EntityRenderer::Instance()->Get3DCamera();
			if (camera == FOLLOWCAM)
				FOLLOWCAM->OnDefendersSpawned();
		}
		else
			m_SpawnTimer -= g_fDeltaTime;
	}

void
init( void )
{
  // Read model in
  woman.LoadMesh( "woman" );

  // Load shaders and use the resulting shader program
  GLuint program = InitShader( "shaders/vshader.glsl", "shaders/fshader.glsl" );
  glUseProgram( program );

  GLuint loc;

  // Initialize shader lighting parameters
  point4 light_position( 0.0, 0.0, 1.0, 0.0 );
  color4 light_ambient( 0.5, 0.5, 0.5, 1.0 );
  color4 light_diffuse( 1.0, 1.0, 1.0, 1.0 );

  // Calculate products
  color4 ambient_product = light_ambient;

  // Pass in light products
  glUniform4fv( glGetUniformLocation( program, "AmbientProduct" ),
                1, ambient_product );
  glUniform4fv( glGetUniformLocation( program, "DiffuseProduct" ),
                1, light_diffuse );
  glUniform4fv( glGetUniformLocation( program, "LightPosition" ),
                1, light_position );
  MaterialColorLoc = glGetUniformLocation( program, "MaterialColor" );

  // Set our vertex projection matrix
  orthoProjection = Ortho( -20.0, 20.0, -20.0, 20.0, -20.0, 20.0 );
  loc = glGetUniformLocation( program, "Projection" );
  glUniformMatrix4fv( loc, 1, GL_TRUE, orthoProjection );

  // Set up our camera
  vec4 eye( 0.0, 0.0, 1.0, 1.0 );
  vec4 at( 0.0, 0.0, 0.0, 1.0 );
  vec4 up( 0.0, 1.0, 0.0, 0.0 );
  N = LookAt( eye, at, up );
  glUniformMatrix4fv( glGetUniformLocation( program, "ModelView" ),
                      1, GL_TRUE, N );

  glEnable( GL_DEPTH );
  glClearColor( 1.0, 1.0, 1.0, 1.0 ); // white background
}

		NViewDataSet NRealisticCamerasRing(size_t nviews, size_t npoints,
			const NViewDatasetConfigurator config)
		{
			// 设置相机参数
			NViewDataSet d;
			d.actual_camera_num_ = nviews;
			d.camera_matrix_.resize(nviews);
			d.rotation_matrix_.resize(nviews);
			d.translation_vector_.resize(nviews);
			d.camera_center_.resize(nviews);
			d.projected_points_.resize(nviews);
			d.projected_point_ids_.resize(nviews);

			d.point_3d_.resize(3, npoints);
			d.point_3d_.setRandom();
			d.point_3d_ *= 0.6;

			Vecu all_point_ids(npoints);
			for (size_t j = 0; j < npoints; ++j)
				all_point_ids[j] = j;

			for (size_t i = 0; i < nviews; ++i) {
				Vec3 camera_center, t, jitter, lookdir;

				const double theta = i * 2 * M_PI / nviews;
				// 圆的方程式
				camera_center << sin(theta), 0.0, cos(theta); // Y axis UP
				camera_center *= config._dist;
				d.camera_center_[i] = camera_center;

				jitter.setRandom();
				jitter *= config._jitter_amount / camera_center.norm();
				lookdir = -camera_center + jitter;

				d.camera_matrix_[i] << config._fx, 0, config._cx,
					0, config._fy, config._cy,
					0, 0, 1;
				d.rotation_matrix_[i] = LookAt(lookdir);  // Y axis UP
				d.translation_vector_[i] = -d.rotation_matrix_[i] * camera_center; // [t]=[-RC] Cf HZ.
				d.projected_points_[i] = Project(d.P(i), d.point_3d_);
				d.projected_point_ids_[i] = all_point_ids;
			}
			return d;
		}

NViewDataSet NRealisticCamerasRing(size_t nviews, size_t npoints,
                                   const nViewDatasetConfigurator config)
{
  //-- Setup a camera circle rig.
  NViewDataSet d;
  d._n = nviews;
  d._K.resize(nviews);
  d._R.resize(nviews);
  d._t.resize(nviews);
  d.C.resize(nviews);
  d._x.resize(nviews);
  d._x_ids.resize(nviews);

  d.X.resize(3, npoints);
  d.X.setRandom();
  d.X *= 0.6;

  Vecu all_point_ids(npoints);
  for (size_t j = 0; j < npoints; ++j)
    all_point_ids[j] = j;

  for (size_t i = 0; i < nviews; ++i) {
    Vec3 camera_center, t, jitter, lookdir;

    const double theta = i * 2 * M_PI / nviews;
    //-- Circle equation
    camera_center << sin(theta), 0.0, cos(theta); // Y axis UP
    camera_center *= config._dist;
    d.C[i] = camera_center;

    jitter.setRandom();
    jitter *= config._jitter_amount / camera_center.norm();
    lookdir = -camera_center + jitter;

    d._K[i] << config._fx,           0, config._cx,
                        0,  config._fy, config._cy,
                        0,           0,          1;
    d._R[i] = LookAt(lookdir);  // Y axis UP
    d._t[i] = -d._R[i] * camera_center; // [t]=[-RC] Cf HZ.
    d._x[i] = Project(d.P(i), d.X);
    d._x_ids[i] = all_point_ids;
  }
  return d;
}

FocusCamera::FocusCamera(Level * level_, GameObject * focus_, Vec3 position_) : Camera(level_){
	focus = focus_;

	stateMachine.ChangeState(new ::Stare(this));
	
	behaviour = LookState::Stare;
	position = position_;
	if (focus){
		followDistance = Vec3::length(position - focus->position);
		LookAt(focus->position);
		MinCameraDistance = int(followDistance / 3.0f);
		MaxCameraDistance = int(followDistance * 3.0f);
		selfieStick = position - focus->position;
	}

	xInverted = 1;
	yInverted = 1;
	lookSpeed = 1.f;
}

void Pointer::Update(float timeStep_)
{
	GameObject::Update(timeStep_);

	position.y = ball->position.y;

	if (Input->isKeyDown(SDLK_RIGHT) || Input->isKeyDown(SDLK_d))
	{
		RotateAround(ball->position, Vec3::BasisY(), 3 * timeStep_);
	}
	if (Input->isKeyDown(SDLK_LEFT) || Input->isKeyDown(SDLK_a))
	{
		RotateAround(ball->position, Vec3::BasisY(), -3 * timeStep_);

	}

	if (Input->isKeyReleased(SDLK_k))
		followCam = !followCam;

	if (Input->isMouseDown(SDL_BUTTON_RIGHT) && followCam)
	{
		//RotateAround(ball->position, Vec3::BasisY(), Input->deltaMouse().x * timeStep_);
		PointAtBall();
	}

	if (((DIY_Level*)GAME->currentLevel)->levelState == DIY_Level_State::PLAYING &&
		((DIY_Level*)GAME->currentLevel)->playingState == DIY_Level_Playing_State::SHOOTING)
	{
		if (!isEnabled)
		{
			PointAtBall();
		}
		isEnabled = true;
	}
	else
		isEnabled = false;

	renderer->isEnabled = isEnabled;

	//position += (level->currentCamera->right() * 0.5f);
	LookAt(ball->position);
	Rotate(Quat(M_PI / 2, Vec3::BasisY()));
}

        // Called when the state should become visible and start runnnig
        void GameState::Enter()
        {
            // Create Camera
            auto cameraNode = _scene->CreateChild("Camera");
            
            auto camera = cameraNode->CreateComponent<Urho3D::Camera>();
            auto soundListener = cameraNode->CreateComponent<Urho3D::SoundListener>();
             
             cameraNode->SetPosition(Urho3D::Vector3(0.f, 10.f, -10.f));
             cameraNode->LookAt(Urho3D::Vector3(0, 0, 0));
             
            // Setup viewport
            Urho3D::SharedPtr<Urho3D::Viewport> viewport(new Urho3D::Viewport(context_, _scene, camera));
			GetSubsystem<Urho3D::Renderer>()->SetViewport(0, viewport);
			GetSubsystem<Urho3D::Audio>()->SetListener(soundListener);
            
            // Set debug camera view
            _scene->GetComponent<Urho3D::DebugRenderer>()->SetView(camera);
        }

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

	// Create new eye vector from sphericaleye vector
	eye.z = sphericaleye.x * cos(sphericaleye.y) * sin(sphericaleye.z);
	eye.x = sphericaleye.x * sin(sphericaleye.y) * sin(sphericaleye.z);
	eye.y = sphericaleye.x * cos(sphericaleye.z);

	std::cout << "Eye: (" << eye.x << "," << eye.y << "," << eye.z << ")  \t";
	std::cout << "Spherical Eye: (" << sphericaleye.x << "," << sphericaleye.y << "," << sphericaleye.z << ")" << std::endl;

    mat4 model_view = LookAt( eye, at, up );
    glUniformMatrix4fv( ModelView, 1, GL_TRUE, model_view );

    glDrawElements( GL_TRIANGLE_STRIP,sizeof(elems),GL_UNSIGNED_BYTE,NULL);
    glutSwapBuffers();
}

void RenderScene(void) {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
    glFrontFace(GL_CW);
    glUseProgram(shader);
    M3DVector3f at={0.0f, 0.0f, 0.0f};
    M3DVector3f up={0.0f, 0.0f, 1.0f};
    M3DVector3f eye;
    float angle = timer.GetElapsedSeconds()*3.14159f/8;
    eye[0]= 6.8f * cos(angle);
    eye[1]= 6.0f * sin(angle);
    eye[2]= 25.0f;
    LookAt(cameraFrame,eye,at,up);

    projection.LoadMatrix(viewFrustum.GetProjectionMatrix());
    modelView.PushMatrix();
    M3DMatrix44f mCamera;
    cameraFrame.GetCameraMatrix(mCamera);

    modelView.LoadMatrix(mCamera);
    modelView.PushMatrix();
	glUniformMatrix4fv(MVMatrixLocation,1,GL_FALSE,geometryPipeline.GetModelViewProjectionMatrix());
		szachownica();
    modelView.Translate(0.0f, 0.0f, 0.0f);
    glUniformMatrix4fv(MVMatrixLocation,1,GL_FALSE,geometryPipeline.GetModelViewProjectionMatrix());
		rysujPiramidke();
    modelView.PopMatrix();
    modelView.PushMatrix();
    modelView.Translate(5.0f, 0.0f, 0.0f);
    glUniformMatrix4fv(MVMatrixLocation,1,GL_FALSE,geometryPipeline.GetModelViewProjectionMatrix());
		rysujPiramidke();
    modelView.PopMatrix();
    modelView.PushMatrix();
    modelView.Translate(-5.0f, 0.0f, 0.0f);
    modelView.Scale(2.0f, 2.0f, 2.0f);
    glUniformMatrix4fv(MVMatrixLocation,1,GL_FALSE,geometryPipeline.GetModelViewProjectionMatrix());
		rysujPiramidke();
    modelView.PopMatrix();
    modelView.PopMatrix();

	glutSwapBuffers();
    glutPostRedisplay();
}

void Entity::rotate(glm::vec3 rotation)
{
	
	this->_modelMatrix = glm::rotate(this->_modelMatrix, rotation.x, glm::vec3(1.0f, 0.0f, 0.0f));
	this->_modelMatrix = glm::rotate(this->_modelMatrix, rotation.y, glm::vec3(0.0f, 1.0f, 0.0f));
	this->_modelMatrix = glm::rotate(this->_modelMatrix, rotation.z, glm::vec3(0.0f, 0.0f, 1.0f));
	
	//Quaternion to avoid Gimbol Lock
	glm::vec3 gPosition1(-1.5f, 0.0f, 0.0f);
	glm::vec3 gPosition2( 1.5f, 0.0f, 0.0f);
	glm::vec3 desiredDir = gPosition1-gPosition2;
	glm::vec3 desiredUp = glm::vec3(0.0f, 0.0f, 1.0f); // +Y
 
	// Compute the desired orientation
	glm::quat targetOrientation = glm::normalize(LookAt(desiredDir, desiredUp));
 
	// And interpolate
	glm::quat gOrientation2 = RotateTowards(gOrientation2, targetOrientation, 1.0f*0.5f);
	
}