ChocolateBird/shaders/palette_shader.tres

[gd_resource type="Shader" format=2]

[resource]
code = "shader_type canvas_item;
//uniform usampler2D tex;
uniform sampler2D palette;
const float index_scale = 255.0 / 16.0;

void fragment() {
	// GLES3
	/*uint color_idx = uint(textureLod(TEXTURE, UV, 0.0).r * 255.0);
	COLOR = texelFetch(palette, ivec2(int(color_idx), 0), 0);
	if (color_idx == uint(0))
		COLOR.a = 0.0;*/
	// GLES2
	float color_idx = texture(TEXTURE, UV).a * index_scale;
	COLOR = texture(palette, vec2(color_idx, 0.5));
	if (color_idx == 0.0)
		COLOR.a = 0.0;
}
"