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// 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
void main()
{
vec4 color_tex;
vec2 color_map_coord;
// normalized texture coordinates ..
color_tex = texture2D(color_texture, gl_TexCoord[0].st);
// 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);
gl_FragColor = texture2D(colortable_texture, (color_map_coord+vec2(0.5)) / colortable_pow2_sz);
}
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