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shader_type canvas_item;
uniform sampler2D screen_texture : hint_screen_texture, repeat_disable, filter_nearest;
uniform float brightness : hint_range(-1, 1) = 0;
uniform sampler2D source_palette;
uniform sampler2D target_palette;
void fragment() {
vec4 screen_color = texture(screen_texture, SCREEN_UV);
ivec2 pal_size = textureSize(source_palette, 0);
float color_diff = 1.0;
int nearest_swatch = 0;
for (int swatch=0; swatch < pal_size.x; swatch++) {
vec4 sampled_color = texelFetch(source_palette, ivec2(swatch,0), 0);
float new_color_diff = distance(sampled_color, screen_color);
if (new_color_diff < color_diff) {
color_diff = new_color_diff;
nearest_swatch = swatch;
}
}
int swatch_offset = int(brightness * float(pal_size.x));
int target_swatch = clamp(nearest_swatch + swatch_offset, 0, pal_size.x -1);
COLOR = texelFetch(target_palette, ivec2(target_swatch, 0), 0);
}
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