TicEditor/Dither.lua at main · speedoog/TicEditor · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128


-- ---------------------------------------------------------------------
-- 							Dithering
-- ---------------------------------------------------------------------

Bayer2x2 = {
	{0,2},
	{3,1},
}

Bayer4x4 = {
	{0, 8, 2, 10},
	{12,4, 14,6},
	{3, 11,1, 9},
	{15,7, 13,5},
}

Bayer8x8 = {
	{0, 32,8, 40,2, 34,10,42},
	{48,16,56,24,50,18,58,26},
	{12,44,4, 36,14,46,6, 38},
	{60,28,52,20,62,30,54,22},
	{3, 35,11,43,1, 33,9, 41},
	{51,19,59,27,49,17,57,25},
	{15,47,7, 39,13,45,5, 37},
	{63,31,55,23,61,29,53,21},
	Size = 8,
	Mask = 7,
	Max = 63,
	IsAbove = function(_,k,x,y)
		local bayer_x = _[(x&_.Mask)+1]
		return k*_.Max > bayer_x[(y&_.Mask)+1]
	end
}

Bayer16x16 ={
	{0, 128,32, 160,8,  136,40, 168,2,  130,34, 162,10, 138,42, 170},
	{192,64, 224,96, 200,72, 232,104,194,66, 226,98, 202,74, 234,106},
	{48, 176,16, 144,56, 184,24, 152,50, 178,18, 146,58, 186,26, 154},
	{240,112,208,80, 248,120,216,88, 242,114,210,82, 250,122,218,90},
	{12, 140,44, 172,4,  132,36, 164,14, 142,46, 174,6,  134,38, 166},
	{204,76, 236,108,196,68, 228,100,206,78, 238,110,198,70, 230,102},
	{60, 188,28, 156,52, 180,20, 148,62, 190,30, 158,54, 182,22, 150},
	{252,124,220,92, 244,116,212,84, 254,126,222,94, 246,118,214,86},
	{3,  131,35, 163,11, 139,43, 171,1,  129,33, 161,9,  137,41, 169},
	{195,67, 227,99, 203,75, 235,107,193,65, 225,97, 201,73, 233,105},
	{51, 179,19, 147,59, 187,27, 155,49, 177,17, 145,57, 185,25, 153},
	{243,115,211,83, 251,123,219,91, 241,113,209,81, 249,121,217,89},
	{15, 143,47, 175,7,  135,39, 167,13, 141,45, 173,5,  133,37, 165},
	{207,79, 239,111,199,71, 231,103,205,77, 237,109,197,69, 229,101},
	{63, 191,31, 159,55, 183,23, 151,61, 189,29, 157,53, 181,21, 149},
	{255,127,223,95, 247,119,215,87, 253,125,221,93, 245,117,213,85}
}

-- sample
--	ditherrect(0,0,30,136,136,2,3)

function ditherrect(x,y,w,h,fadeThickness,c1,c2)
	local horizontal = false
	local matrixSize = 8

	local matrix
	if matrixSize == 2 then
		matrix = Bayer2x2
	elseif matrixSize == 4 then
		matrix = Bayer4x4
	else
		matrixSize = 8
		matrix = Bayer8x8
	end

	dimension = #matrix

	local centerOffset, startX, startY, endX, endY
	if horizontal then
		centerOffset = w / 2 - fadeThickness / 2
		rect(x, y, centerOffset, h, c1)
		startX = x + centerOffset
		endX = x + fadeThickness + centerOffset
		startY = y
		endY = y + h
	else
		centerOffset = h / 2 - fadeThickness / 2
		rect(x, y, w, centerOffset, c1)
		startX = x
		endX = x + w
		startY = y + centerOffset
		endY = y + fadeThickness + centerOffset
	end

	local x1,x2, y1, y2
	for x1=startX,endX-1 do
		for y1=startY,endY-1 do
			if horizontal then
				x2 = x1 - x - centerOffset
				y2 = y1 - y
			else
				x2 = x1 - x
				y2 = y1 - y - centerOffset
			end
			local threshold = matrix[x2 % dimension+1][y2 % dimension+1]

			local t
			if horizontal then
				t = (x2 / fadeThickness) * (matrixSize * matrixSize - 1)
			else
				t = (y2 / fadeThickness) * (matrixSize * matrixSize - 1)
			end

			local color
			if t < threshold then
				color=c1
			else
				color=c2
			end

			pix(x1, y1, color)
		end
	end

	if horizontal then
		rect(endX, y, centerOffset, h, c2)
	else
		rect(x, endY, w, centerOffset, c2)
	end
end