;;; Gacela, a GNU Common Lisp extension for fast games development
;;; Copyright (C) 2009 by Javier Sancho Fernandez <jsf at jsancho dot org>
;;;
;;; This program is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published by
;;; the Free Software Foundation, either version 3 of the License, or
;;; (at your option) any later version.
;;;
;;; This program is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program.  If not, see <http://www.gnu.org/licenses/>.


(in-package :gacela)

(defun draw (&rest vertexes)
  (begin-draw (length vertexes))
  (draw-vertexes vertexes)
  (glEnd))

(defun begin-draw (number-of-points)
  (cond ((= number-of-points 3) (glBegin GL_TRIANGLES))
	((= number-of-points 4) (glBegin GL_QUADS))))

(defun draw-vertexes (vertexes)
  (cond ((null vertexes) nil)
	(t (draw-vertex (car vertexes))
	   (draw-vertexes (cdr vertexes)))))

(defun draw-vertex (vertex &key texture-coord)
  (cond ((consp (car vertex)) (apply #'glColor3f (car vertex)) (apply #'glVertex3f (cadr vertex)))
	(t (cond (texture-coord (apply #'glTexCoord2f texture-coord)))
	   (apply #'glVertex3f vertex))))

(defun draw-color (color)
  (apply #'glColor3f color))

(defun load-texture (filename &optional (min-filter GL_LINEAR) (mag-filter GL_LINEAR))
;  (init-textures)
  (init-video-mode)
  (let ((image (IMG_Load filename))
	(texture (car (glGenTextures 1))))
    (cond ((/= image 0)
	   (glBindTexture GL_TEXTURE_2D texture)
	   (glTexImage2D GL_TEXTURE_2D 0 3 (surface-w image) (surface-h image) 0 GL_BGR GL_UNSIGNED_BYTE (surface-pixels image))
	   (glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MIN_FILTER min-filter)
	   (glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MAG_FILTER mag-filter)
	   (SDL_FreeSurface image)))
    texture))

(defun draw-quad (v1 v2 v3 v4 &key texture color)
  (cond (texture (glBindTexture GL_TEXTURE_2D texture)
		 (begin-draw 4)
		 (draw-vertex v1 :texture-coord '(0 0))
		 (draw-vertex v2 :texture-coord '(1 0))
		 (draw-vertex v3 :texture-coord '(1 1))
		 (draw-vertex v4 :texture-coord '(0 1))
		 (glEnd))
	(t (cond (color (draw-color color)))
	   (draw v1 v2 v3 v4))))

(defun draw-square (&key size texture color)
  (let ((-size (neg size)))
    (draw-quad (list -size size 0) (list size size 0) (list size -size 0) (list -size -size 0) :texture texture :color color)))

(defun draw-cube (&key size texture color)
  (let ((-size (neg size)))
    (enable :textures texture)
    (glNormal3f 0 0 1)
    (draw-quad (list -size size size) (list size size size) (list size -size size) (list -size -size size) :texture texture :color color)
    (glNormal3f 0 0 -1)
    (draw-quad (list -size -size -size) (list size -size -size) (list size size -size) (list -size size -size) :texture texture :color color)
    (glNormal3f 0 1 0)
    (draw-quad (list size size size) (list -size size size) (list -size size -size) (list size size -size) :texture texture :color color)
    (glNormal3f 0 -1 0)
    (draw-quad (list -size -size size) (list size -size size) (list size -size -size) (list -size -size -size) :texture texture :color color)
    (glNormal3f 1 0 0)
    (draw-quad (list size -size -size) (list size -size size) (list size size size) (list size size -size) :texture texture :color color)
    (glNormal3f -1 0 0)
    (draw-quad (list -size -size size) (list -size -size -size) (list -size size -size) (list -size size size) :texture texture :color color)))

(defun add-light (&key light position ambient (id GL_LIGHT1) (turn-on t))
  (init-lighting)
  (and light (glLightfv id GL_DIFFUSE (first light) (second light) (third light) (fourth light)))
  (and light position (glLightfv GL_POSITION (first position) (second position) (third position) (fourth position)))
  (and ambient (glLightfv id GL_AMBIENT (first ambient) (second ambient) (third ambient) (fourth ambient)))
  (and turn-on (glEnable id))
  id)

(defun translate (x y &optional (z 0))
  (glTranslatef x y z))

(defun rotate (xrot yrot &optional zrot)
  (glRotatef xrot 1 0 0)
  (glRotatef yrot 0 1 0)
  (cond (zrot (glRotatef zrot 0 0 1))))

(defun enable (&key textures)
  (cond (textures (glEnable GL_TEXTURE_2D))))