123 lines
2.7 KiB
Forth
123 lines
2.7 KiB
Forth
#! /usr/bin/env ueforth
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\ Copyright 2022 Bradley D. Nelson
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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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also graphics
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also structures
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struct ScanSpan
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ptr field ->next
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ptr field ->edge
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1024 constant max-scanlines
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create scanlines max-scanlines cells allot
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scanlines max-scanlines cells erase
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0 value free-edges
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: new-edge ( n next -- a )
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free-edges if
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free-edges dup ->next @ to free-edges
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else
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ScanSpan allocate throw
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then
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{ np }
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np ->next !
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np ->edge !
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np
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;
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: row-span ( y -- a ) cells scanlines + ;
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: add-edge { x y }
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y row-span { yp }
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begin yp @ while
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x yp @ ->edge @ <= if
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x yp @ new-edge yp !
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exit
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then
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yp @ ->next to yp
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repeat
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x yp @ new-edge yp !
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;
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: remove-edge ( y -- x )
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row-span { yp }
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yp @ 0= if 10000 exit then
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yp @ { old }
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yp @ ->edge @
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yp @ ->next @ yp !
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free-edges old ->next !
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old to free-edges
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;
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: draw-row { y }
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begin y row-span @ while
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y remove-edge y remove-edge over - y swap 1 box
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repeat
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;
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: draw-spans max-scanlines 0 do i draw-row loop ;
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: 2span { a b -- n } a b max a b min - ;
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: 3span { a b c -- n } a b max c max a b min c min - ;
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: bezier 0 0 0 0 0 0 { x1 y1 x2 y2 x3 y3 x1.5 x2.5 y1.5 y2.5 xn yn }
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y1 y2 y3 3span 2 < if
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y1 y3 2span if
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x1 x3 + 2/ y1 y2 min y3 min add-edge
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then
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else
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x1 x2 + 2/ to x1.5 x2 x3 + 2/ to x2.5
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y1 y2 + 2/ to y1.5 y2 y3 + 2/ to y2.5
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x1 x2 2* + x3 + 2/ 2/ to xn
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y1 y2 2* + y3 + 2/ 2/ to yn
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x1 y1 x1.5 y1.5 xn yn recurse
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xn yn x2.5 y2.5 x3 y3 recurse
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then
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;
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: line ( x1 y1 x2 y2 ) 2dup bezier ;
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0 value pen-x 0 value pen-y
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: move-to { x y } x to pen-x y to pen-y ;
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: line-to { x y } pen-x pen-y x y line x y move-to ;
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: bezier-to { x' y' x y } pen-x pen-y x' y' x y bezier x y move-to ;
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-1 -1 window
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$ff0000 constant red
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$ffff00 constant yellow
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$ffffff constant white
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$000000 constant black
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$0000bb constant blue
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: draw
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black to color 0 0 width height box
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yellow to color 0 0 width 2/ height 2/ box
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red to color
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width 3 / 100 move-to
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mouse-x 1 mouse-x mouse-y bezier-to
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mouse-x 2/ 1 line-to
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300 200 200 400 bezier-to
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1 mouse-y 2 3 */ line-to
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width 3 / 100 line-to
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blue to color draw-spans
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flip
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;
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: run
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begin
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poll
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IDLE event = if draw then
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event FINISHED = until
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bye
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;
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run
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