ascii_tilemap_shadermaterial.tres

[gd_resource type="ShaderMaterial" load_steps=3 format=3 uid="uid://bc7kfuwl8i4xp"]

[ext_resource type="Texture2D" uid="uid://kdm0pyu6qvmo" path="res://images/cp437_14x14.png" id="1"]

[sub_resource type="Shader" id="1"]
code = "shader_type canvas_item;

uniform sampler2D tileset;
uniform vec2 glyph_size;
uniform sampler2D tilemap_ids;
uniform sampler2D tilemap_colors;
uniform vec2 tilemap_size;

float srgb_to_linear(float srgb) {
	if(srgb <= 0.0031308) {
		return srgb * 12.92;
	} else {
		return pow(srgb, 1.0 / 2.4) * 1.055 - 0.055;
	}
}

vec4 vec4_srgb_to_linear(vec4 srgb) {
	return vec4(srgb_to_linear(srgb.r), srgb_to_linear(srgb.g), srgb_to_linear(srgb.b), srgb.a);
}

void fragment() {
	// Get tile ID in tileset from tilemap_data
	ivec2 tilemap_data_space = ivec2(UV * vec2(tilemap_size));
	lowp int tile_id = int(texelFetch(tilemap_ids, tilemap_data_space, 0).r * 255.);
	// Get foreground and background colors from tilemap_data
	tilemap_data_space.x *= 2;
	vec4 fg = vec4_srgb_to_linear(texelFetch(tilemap_colors, ivec2(tilemap_data_space.x, tilemap_data_space.y), 0));
	vec4 bg = vec4_srgb_to_linear(texelFetch(tilemap_colors, ivec2(tilemap_data_space.x + 1, tilemap_data_space.y), 0));
	// Get either black or white from the tileset
	// Choose the foreground color if white, background color if black
	ivec2 tileset_coord = ivec2(tile_id % 16, int(float(tile_id) / 16.));
	ivec2 position_within_glyph = ivec2(UV * tilemap_size * glyph_size) % ivec2(glyph_size);
	vec4 tileset_color = texelFetch(tileset, (tileset_coord * ivec2(glyph_size)) + position_within_glyph, 0);
	if (tileset_color == vec4(1.)) {
		COLOR = fg;
	} else {
		COLOR = bg;
	}
}"

[resource]
shader = SubResource("1")
shader_parameter/glyph_size = Vector2(14, 14)
shader_parameter/tilemap_size = Vector2(21, 16)
shader_parameter/tileset = ExtResource("1")