70 lines
2.2 KiB
Scheme
70 lines
2.2 KiB
Scheme
;;; Copyright (C) 2024 David Thompson <dave@spritely.institute>
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;;;
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;;; Licensed under the Apache License, Version 2.0 (the "License");
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;;; you may not use this file except in compliance with the License.
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;;; You may obtain a copy of the License at
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;;;
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;;; http://www.apache.org/licenses/LICENSE-2.0
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;;;
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;;; Unless required by applicable law or agreed to in writing, software
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;;; distributed under the License is distributed on an "AS IS" BASIS,
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;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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;;; See the License for the specific language governing permissions and
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;;; limitations under the License.
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(define-module (game animation)
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#:use-module (game tileset)
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#:use-module (ice-9 match)
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#:use-module (srfi srfi-9)
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#:export (make-frame
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frame?
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frame-tile
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frame-duration
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make-animation
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animation?
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animation-tileset
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animation-time
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animation-frames
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update-animation
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draw-animation))
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(define-record-type <frame>
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(make-frame tile duration)
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frame?
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(tile frame-tile)
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(duration frame-duration))
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(define-record-type <animation>
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(%make-animation tileset frames time frame-idx)
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animation?
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(tileset animation-tileset)
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(frames animation-frames)
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(time animation-time set-animation-time!)
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(frame-idx animation-frame-idx set-animation-frame-idx!))
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(define (make-animation tileset frames)
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(%make-animation tileset frames 0.0 0))
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(define (flonum? x)
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(and (real? x) (inexact? x)))
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(define (update-animation anim dt)
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(unless (flonum? dt)
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(error "not a flonum" dt))
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(match anim
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(($ <animation> tileset frames (? flonum? time) idx)
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(let ((time* (+ time dt)))
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(match (vector-ref frames idx)
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(($ <frame> tile duration)
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(cond
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((>= time* duration)
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(set-animation-frame-idx! anim (modulo (1+ idx) (vector-length frames)))
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(set-animation-time! anim (- time* duration)))
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(else
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(set-animation-time! anim time*)))))))))
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(define (draw-animation context anim x y)
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(match anim
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(($ <animation> tileset frames time idx)
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(draw-tile context tileset (frame-tile (vector-ref frames idx)) x y))))
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