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
|
// license:BSD-3-Clause
// copyright-holders:Sven Gothel
#pragma optimize (on)
#pragma debug (off)
uniform sampler2D color_texture;
uniform sampler2D colortable_texture;
uniform vec2 colortable_sz; // ct size
uniform vec2 colortable_pow2_sz; // pow2 ct size
uniform vec2 color_texture_pow2_sz; // pow2 tex size
vec4 lutTex2D(in vec2 texcoord)
{
vec4 color_tex;
vec2 color_map_coord;
// normalized texture coordinates ..
color_tex = texture2D(color_texture, texcoord);
// GL_UNSIGNED_SHORT GL_ALPHA in ALPHA16 conversion:
// general: f = c / ((2*N)-1), c color bitfield, N number of bits
// ushort: c = ((2**16)-1)*f;
color_map_coord.x = floor( 65535.0 * color_tex.a + 0.5 );
// map it to the 2D lut table
color_map_coord.y = floor(color_map_coord.x/colortable_sz.x);
color_map_coord.x = mod(color_map_coord.x,colortable_sz.x);
return texture2D(colortable_texture, (color_map_coord+vec2(0.5)) / colortable_pow2_sz);
}
void main()
{
vec2 xy = gl_TexCoord[0].st;
// mix(x,y,a): x*(1-a) + y*a
//
// bilinear filtering includes 2 mix:
//
// pix1 = tex[x0][y0] * ( 1 - u_ratio ) + tex[x1][y0] * u_ratio
// pix2 = tex[x0][y1] * ( 1 - u_ratio ) + tex[x1][y1] * u_ratio
// fin = pix1 * ( 1 - v_ratio ) + pix2 * v_ratio
//
// so we can use the build in mix function for these 2 computations ;-)
//
vec2 uv_ratio = fract(xy*color_texture_pow2_sz); // xy*color_texture_pow2_sz - floor(xy*color_texture_pow2_sz);
vec2 one = 1.0/color_texture_pow2_sz;
vec4 col1, col2;
col1 = mix( lutTex2D(xy ), lutTex2D(xy + vec2(one.x, 0.0)), uv_ratio.x);
col2 = mix( lutTex2D(xy + vec2(0.0, one.y)), lutTex2D(xy + one ), uv_ratio.x);
gl_FragColor = mix ( col1, col2, uv_ratio.y );
}
|