//***********************************************************
//
// Name:		Camera.H
// Last Update: 24/2/02
// Author:		Poya Manouchehri
//
// Description: CCamera holds a view and a projection matrix.
//				It also has a frustum which can be used to
//				cull objects for rendering.
//
//***********************************************************

#ifndef CAMERA_H
#define CAMERA_H

#include "Frustum.h"
#include "maths/Matrix3D.h"

extern int g_mouse_x, g_mouse_y;

// view port
struct SViewPort
{
	unsigned int m_X;
	unsigned int m_Y;
	unsigned int m_Width;
	unsigned int m_Height;
};


class CCamera
{
	public:
		CCamera ();
		~CCamera ();
		
		// Methods for projection
		void SetProjection (CMatrix3D *proj) { m_ProjMat = *proj; }
		void SetProjection (float nearp, float farp, float fov);
		void SetProjectionTile (int tiles, int tile_x, int tile_y);
		CMatrix3D GetProjection () { return m_ProjMat; }

		// Updates the frustum planes. Should be called
		// everytime the view or projection matrices are
		// altered.
		void UpdateFrustum ();
		CFrustum GetFrustum () { return m_ViewFrustum; }

		void SetViewPort (SViewPort *viewport);
		SViewPort GetViewPort () { return m_ViewPort; }

		// getters
		float GetNearPlane() const { return m_NearPlane; }
		float GetFarPlane() const { return m_FarPlane; }
		float GetFOV() const { return m_FOV; }

		// calculate and return the position of the 8 points of the frustum in world space
		void GetFrustumPoints(CVector3D pts[8]) const;

		// return four points in camera space at given distance from camera
		void GetCameraPlanePoints(float dist,CVector3D pts[4]) const;

		// Build a ray passing through the screen coordinate (px, py) and the camera
		/////////////////////////////////////////////////////////////////////////////////////////
		// BuildCameraRay: calculate origin and ray direction of a ray through
		// the pixel (px,py) on the screen
		void BuildCameraRay(int px, int py, CVector3D& origin, CVector3D& dir);
		// BuildCameraRay: as previous, using global mouse position
		void BuildCameraRay(CVector3D& origin, CVector3D& dir)
		{
			BuildCameraRay(g_mouse_x, g_mouse_y, origin, dir);
		}

		// General helpers that seem to fit here

		// Get the screen-space coordinates corresponding to a given world-space position 
		void GetScreenCoordinates(const CVector3D& world, float& x, float& y) const;

		// Get the point on the terrain corresponding to pixel (px,py) (or the mouse coordinates)
		CVector3D GetWorldCoordinates(int px, int py);
		CVector3D GetWorldCoordinates() { return GetWorldCoordinates(g_mouse_x, g_mouse_y); }
		// Get the point on the plane at height h corresponding to pixel (px,py)
		CVector3D GetWorldCoordinates(int px, int py, float h);
		// Get the point on the terrain the camera is pointing towards
		CVector3D GetFocus();

		// Build an orientation matrix from camera position, camera focus point, and up-vector
		void LookAt(const CVector3D& camera, const CVector3D& orientation, const CVector3D& up);

		// Build an orientation matrix from camera position, camera orientation, and up-vector
		void LookAlong(CVector3D camera, CVector3D focus, CVector3D up);

		/**
		 * Render: Renders the camera's frustum in world space.
		 * The caller should set the color using glColorXy before calling Render.
		 * 
		 * @param intermediates determines how many intermediate distance planes should
		 * be hinted at between the near and far planes
		 */
		void Render(uint intermediates = 0) const;
		
	public:
		// This is the orientation matrix. The inverse of this
		// is the view matrix
		CMatrix3D		m_Orientation;
		
		// Should not be tweaked externally if possible
		CMatrix3D		m_ProjMat;

	private:
		float			m_NearPlane;
		float			m_FarPlane;
		float			m_FOV;
		SViewPort		m_ViewPort;

		CFrustum		m_ViewFrustum;
};

#endif
