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#pragma optimize (on)
#pragma debug (off)
uniform sampler2D color_texture;
uniform sampler2D colortable_texture;
uniform vec2 colortable_sz; // orig 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;
vec4 color0;
float colortable_scale = (colortable_sz.x/3.0) / colortable_pow2_sz.x;
// normalized texture coordinates ..
color_tex = texture2D(color_texture, texcoord) * ((colortable_sz.x/3.0)-1.0)/colortable_pow2_sz.x;// lookup space
color_map_coord.x = color_tex.b;
color0.b = texture2D(colortable_texture, color_map_coord).b;
color_map_coord.x = color_tex.g + colortable_scale;
color0.g = texture2D(colortable_texture, color_map_coord).g;
color_map_coord.x = color_tex.r + 2.0 * colortable_scale;
color0.r = texture2D(colortable_texture, color_map_coord).r;
return color0;
}
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 );
}
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