math: Move rect module to sly/math directory.

* sly/rect.scm: Delete.
* sly/math/rect.scm: New file.
* Makefile.am (SOURCES): Add new file.  Delete old one.
* sly/render/camera.scm: Use (sly math rect) module.
* examples/simple.scm: Likewise.

1 files changed, 212 insertions, 0 deletions

diff --git a/sly/math/rect.scm b/sly/math/rect.scm
new file mode 100644
index 0000000..d822891
--- /dev/null
+++ b/sly/math/rect.scm
@@ -0,0 +1,212 @@
+;;; Sly
+;;; Copyright (C) 2013, 2014 David Thompson <dthompson2@worcester.edu>
+;;;
+;;; 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/>.
+
+;;; Commentary:
+;;
+;; Rects are axis-aligned bounding boxes that can be used for
+;; performing simple collision detection.
+;;
+;;; Code:
+
+(define-module (sly math rect)
+  #:use-module (srfi srfi-9)
+  #:use-module (sly math vector)
+  #:export (<rect>
+            make-rect
+            null-rect
+            rect?
+            rect-x
+            rect-y
+            rect-left
+            rect-right
+            rect-top
+            rect-bottom
+            rect-position
+            rect-top-left
+            rect-top-right
+            rect-bottom-left
+            rect-bottom-right
+            rect-center-x
+            rect-center-y
+            rect-center
+            rect-half-width
+            rect-half-height
+            rect-width
+            rect-height
+            rect-size
+            rect-move
+            rect-inflate
+            rect-union
+            rect-clip
+            rect-within?
+            rect-intersects?
+            rect-contains?))
+
+;;;
+;;; Rectangles
+;;;
+
+;; The rect API is very similar to the Pygame rect API, but rects are
+;; immutable.
+
+(define-record-type <rect>
+  (%make-rect x y width height)
+  rect?
+  (x rect-x)
+  (y rect-y)
+  (width rect-width)
+  (height rect-height))
+
+(define make-rect
+  (case-lambda
+    ((x y width height)
+     (%make-rect x y width height))
+    ((position size)
+     (%make-rect (vx position) (vy position)
+                 (vx size) (vy size)))))
+
+(define null-rect (make-rect 0 0 0 0))
+
+(define (rect-right rect)
+  (+ (rect-x rect) (rect-width rect)))
+
+(define rect-left rect-x)
+
+(define rect-top rect-y)
+
+(define (rect-bottom rect)
+  (+ (rect-y rect) (rect-height rect)))
+
+(define (rect-position rect)
+  "Return the top-left corner of RECT as a vector."
+  (vector2 (rect-x rect)
+           (rect-y rect)))
+
+(define rect-top-left rect-position)
+
+(define (rect-top-right rect)
+  (vector2 (rect-right rect)
+           (rect-top   rect)))
+
+(define (rect-bottom-left rect)
+  (vector2 (rect-left   rect)
+           (rect-bottom rect)))
+
+(define (rect-bottom-right rect)
+  (vector2 (rect-right  rect)
+           (rect-bottom rect)))
+
+(define (rect-center-x rect)
+  (+ (rect-x rect) (rect-half-width rect)))
+
+(define (rect-center-y rect)
+  (+ (rect-y rect) (rect-half-height rect)))
+
+(define (rect-center rect)
+  (vector2 (rect-center-x rect)
+           (rect-center-y rect)))
+
+(define (rect-half-width rect)
+  (/ (rect-width rect) 2))
+
+(define (rect-half-height rect)
+  (/ (rect-height rect) 2))
+
+(define (rect-size rect)
+  "Return the size of RECT as a vector."
+  (vector2 (rect-width rect)
+           (rect-height rect)))
+
+(define (%rect-move rect x y)
+  "Move RECT by the offset X, Y."
+  (make-rect (+ (rect-x rect) x)
+             (+ (rect-y rect) y)
+             (rect-width rect)
+             (rect-height rect)))
+
+(define rect-move
+  (case-lambda
+    "Create a new rectangle by moving RECT by the given
+offset. rect-move accepts a vector or x and y coordinates as separate
+arguments."
+    ((rect v)
+     (%rect-move rect (vx v) (vy v)))
+    ((rect x y)
+     (%rect-move rect x y))))
+
+(define (%rect-inflate rect width height)
+  "Grows the rect by the given amount. The rect stays centered around
+its current center."
+  (make-rect (+ (rect-x rect) (/ width 2))
+             (+ (rect-y rect) (/ height 2))
+             (+ (rect-width rect) width)
+             (+ (rect-height rect) height)))
+
+(define rect-inflate
+  (case-lambda
+    "Create a new rectangle by growing RECT by the given amount
+without changing the center point. rect-inflate accepts a vector or x
+and y coordinates as separate arguments."
+    ((rect v)
+     (%rect-inflate rect (vx v) (vy v)))
+    ((rect x y)
+     (%rect-inflate rect x y))))
+
+(define (rect-union rect1 rect2)
+  "Return a rect that covers the area of RECT1 and RECT2."
+  (let ((x1 (min (rect-left   rect1) (rect-left   rect2)))
+        (x2 (max (rect-right  rect1) (rect-right  rect2)))
+        (y1 (min (rect-top    rect1) (rect-top    rect2)))
+        (y2 (max (rect-bottom rect1) (rect-bottom rect2))))
+    (make-rect x1 y1 (- x2 x1) (- y2 y1))))
+
+(define (rect-clip rect1 rect2)
+  "Return the overlapping region of RECT1 and RECT2. If the rects do
+not overlap, a rect of size 0 is returned."
+  (let ((x1 (max (rect-left   rect1) (rect-left   rect2)))
+        (x2 (min (rect-right  rect1) (rect-right  rect2)))
+        (y1 (max (rect-top    rect1) (rect-top    rect2)))
+        (y2 (min (rect-bottom rect1) (rect-bottom rect2))))
+    (make-rect x1 y1 (max (- x2 x1) 0) (max (- y2 y1) 0))))
+
+(define (rect-within? rect1 rect2)
+  "Return #t if RECT2 is completely within RECT1."
+  (and (>= (rect-left   rect2) (rect-left   rect1))
+       (<= (rect-right  rect2) (rect-right  rect1))
+       (>= (rect-top    rect2) (rect-top    rect1))
+       (<= (rect-bottom rect2) (rect-bottom rect1))))
+
+(define (rect-intersects? rect1 rect2)
+  "Return #t if RECT2 overlaps RECT1."
+  (and (< (rect-left   rect1) (rect-right  rect2))
+       (> (rect-right  rect1) (rect-left   rect2))
+       (< (rect-top    rect1) (rect-bottom rect2))
+       (> (rect-bottom rect1) (rect-top    rect2))))
+
+(define (%rect-contains? rect x y)
+  (and (>= x (rect-left   rect))
+       (<= x (rect-right  rect))
+       (>= y (rect-top    rect))
+       (<= y (rect-bottom rect))))
+
+(define rect-contains?
+  (case-lambda
+    "Return #t if the given point is within RECT."
+    ((rect v)
+     (%rect-contains? rect (vx v) (vy v)))
+    ((rect x y)
+     (%rect-contains? rect x y))))