Added overlay parchment map and refactored map shader

1 files changed, 108 insertions, 65 deletions

diff --git a/game/src/Game/GameSession/TerrainMap.gdshader b/game/src/Game/GameSession/TerrainMap.gdshader
index 487401f..98f9efd 100644
--- a/game/src/Game/GameSession/TerrainMap.gdshader
+++ b/game/src/Game/GameSession/TerrainMap.gdshader
@@ -13,100 +13,140 @@ uniform sampler2D province_colour_tex: repeat_enable, filter_nearest;
 uniform uint hover_index;
 // Index of the currently selected province
 uniform uint selected_index;
+// How much to mix between the near detailed map (0) and the far parchment map (1)
+uniform float parchment_mix;
 // Cosmetic terrain textures
 uniform sampler2DArray terrain_tex: repeat_enable, filter_linear;
-// The number of times the terrain textures should tile vertically
+// Factor converting pixels to terrain tile size
 uniform float terrain_tile_factor;
 // Map stripe mask texture
 uniform sampler2D stripe_tex: repeat_enable, filter_linear;
-// The number of times the stripe texture should tile vertically
+// Factor converting pixels to stripe tile size
 uniform float stripe_tile_factor;
+// Map parchment overlay texture
+uniform sampler2D overlay_tex: repeat_enable, filter_linear;
+// Factor converting pixels to overlay tile size
+uniform float overlay_tile_factor;
 // Land map tint
 uniform sampler2D colormap_land_tex: repeat_enable, filter_linear;
 // Water map tint
 uniform sampler2D colormap_water_tex: repeat_enable, filter_linear;
+// Overlay map tint
+uniform sampler2D colormap_overlay_tex: repeat_enable, filter_linear;
 
-const vec3 highlight_colour = vec3(1.0);
-// Rec.709 luma coefficients
-const vec3 luma_weights = vec3(0.2126, 0.7152, 0.0722);
-
-struct args_t {
-	vec2 uv, half_pixel_size; // Components for calculating province sampling UV
-	float stripe_mask; // Stripe mask value - between 0 (base) and 1 (stripe)
+struct terrain_args_t {
+	vec2 uv, half_pixel_size; // Components for calculating terrain sampling UV
 	vec2 terrain_uv; // UV coordinates scaled for terrain texture tiling
-	vec3 land_tint_colour, water_tint_colour; // Colours for tinting terrain
+	vec3 land_tint_colour, water_tint_colour; // Colours for tinting the terrain
 };
 
-// TODO - add parchment overlay, borders, coastlines, rivers, fog of war
-// (when borders are added we can move province colour calculations out of get_terrain_colour
-// and into get_map_colour, as we won't need to blend along the borders between provinces)
-
-// This calculates the terrain and base-stripe province colours, blends them together, and then returns
-// either the blended colour or just the terrain colour depending on whether the province colour's alpha
-// value was set. It also highlights the result if the province is currently selected and/or hovered over.
-vec3 get_terrain_colour(const args_t args, const vec2 corner) {
-	// Find the province and terrain indices at the specified corner of a pixel centred on uv
-	uvec3 province_data = read_uvec3(fma(corner, args.half_pixel_size, args.uv));
-	uint province_index = uvec2_to_uint(province_data.rg);
-	uint terrain_index = province_data.b;
-
-	// Get the tinted terrain colour at the current position
-	vec3 terrain_colour = texture(terrain_tex, vec3(args.terrain_uv, float(terrain_index))).rgb;
-	vec3 tint_colour = mix(args.land_tint_colour, args.water_tint_colour, float(terrain_index == 0u));
-	vec3 tinted_terrain_colour = mix(terrain_colour, tint_colour, 0.3);
-	float terrain_luma = dot(tinted_terrain_colour, luma_weights);
+// Calculate terrain colour at the specified corner of the current pixel
+vec3 get_terrain_colour(const terrain_args_t terrain_args, const vec2 corner) {
+	// Find the terrain index at the specified corner of the current pixel
+	uint terrain_index = read_uvec3(fma(corner, terrain_args.half_pixel_size, terrain_args.uv)).z;
 
-	// Get base and stripe colours for province at the current position
-	province_data.r *= 2u; // Double "x coordinate" as colours come in (base, stripe) pairs
-	vec4 province_base_colour = texelFetch(province_colour_tex, ivec2(province_data.rg), 0);
-	province_data.r += 1u; // Add 1 to "x coordinate" to move from base to strip colour
-	vec4 province_stripe_colour = texelFetch(province_colour_tex, ivec2(province_data.rg), 0);
-	// Blend the base and stripe colours according to the current position's stripe mask value
-	vec4 province_colour = mix(province_base_colour, province_stripe_colour, args.stripe_mask);
+	// Get the tinted land colour at the current position
+	vec3 land_colour = texture(terrain_tex, vec3(terrain_args.terrain_uv, float(terrain_index))).rgb;
+	land_colour = mix(land_colour, terrain_args.land_tint_colour, 0.3);
 
-	// Darken the province colour, use it to tint the monochrome terrain colour, and re-lighten the result
-	province_colour.rgb = mix(vec3(terrain_luma), province_colour.rgb - 0.7, 0.3) * 1.5;
+	// TODO - proper water texture
+	vec3 water_colour = terrain_args.water_tint_colour;
 
-	// Show the terrain colour if the province colour has no alpha, otherwise show the province colour
-	vec3 mixed_colour = mix(tinted_terrain_colour, province_colour.rgb, float(province_colour.a != 0.0));
+	// Select land or water colour based on the terrain index (0 is water, otherwise land)
+	vec3 terrain_colour = mix(land_colour, water_colour, float(terrain_index == 0u));
 
-	float highlight_mix_val = 0.4 * (float(province_index == hover_index) + float(province_index == selected_index)) * float(province_index != 0u);
-	return mix(mixed_colour, highlight_colour, highlight_mix_val);
+	return terrain_colour;
 }
 
-// Rescale UV coordinates to remove squashing caused by normalisation
-vec2 denormalise(const vec2 uv, const vec2 dims) {
-	return vec2(uv.x * dims.x / dims.y, uv.y);
+// Blend together terrain colours from the four corners of the current pixel
+vec3 mix_terrain_colour(const terrain_args_t terrain_args, const vec2 pixel_offset) {
+	return mix(
+		mix(get_terrain_colour(terrain_args, vec2(-1, -1)), get_terrain_colour(terrain_args, vec2(+1, -1)), pixel_offset.x),
+		mix(get_terrain_colour(terrain_args, vec2(-1, +1)), get_terrain_colour(terrain_args, vec2(+1, +1)), pixel_offset.x),
+		pixel_offset.y
+	);
 }
 
-// Calculate position-specific values and then calculate and blend map colours at the four corners
-// of a pixel centred at uv in order to have smooth transitions between terrain types.
-vec3 get_map_colour(vec2 uv) {
-	args_t args;
-	args.uv = uv;
+// Mix overlay and base colours, used for the parchment map
+vec3 mix_overlay(const vec3 overlay_colour, const vec3 base_colour) {
+	return mix(
+		2.0 * overlay_colour * base_colour,
+		1.0 - 2.0 * (1.0 - overlay_colour) * (1.0 - base_colour),
+		greaterThanEqual(overlay_colour.rrb, vec3(0.5))
+	);
+}
 
+// Calculate map colour at specified UV coordinates, combining terrain, province base and stripe colour,
+// parchment overlay, and highlighting the result if it is a hovered over and/or selected province.
+vec3 get_map_colour(vec2 uv) {
 	vec2 map_size = vec2(textureSize(province_shape_tex, 0).xy) * province_shape_subdivisions;
-	vec2 uv_centred = fma(uv, map_size, vec2(0.5));
-	vec2 pixel_offset = fract(uv_centred);
-	args.half_pixel_size = 0.49 / map_size;
+	vec2 uv_map_pixels = fma(uv, map_size, vec2(0.5));
+	// Offset of uv_map_pixels from the top left corner of the current pixel
+	vec2 pixel_offset = fract(uv_map_pixels);
+
+	terrain_args_t terrain_args;
+	terrain_args.uv = uv;
+	terrain_args.half_pixel_size = 0.49 / map_size;
+	// Terrain texture tiling UV
+	terrain_args.terrain_uv = 0.5 - uv_map_pixels * terrain_tile_factor;
 
-	// UV coords adjusted to remove squashing caused by normalisation relative to map dimensions
-	vec2 unscaled_uv = denormalise(uv, map_size);
+	vec2 colormap_uv = vec2(uv.x, 1.0 - uv.y);
+	// Terrain tinting colours
+	terrain_args.land_tint_colour = texture(colormap_land_tex, colormap_uv).rgb;
+	terrain_args.water_tint_colour = texture(colormap_water_tex, colormap_uv).rgb;
+	// Parchment tint colour
+	vec3 overlay_tint_colour = texture(colormap_overlay_tex, colormap_uv).rgb;
+
+	// Blended terrain colour (average of four corners of current pixel)
+	vec3 terrain_colour = mix_terrain_colour(terrain_args, pixel_offset);
 
-	vec2 stripe_uv = unscaled_uv * stripe_tile_factor;
+	vec2 stripe_uv = uv_map_pixels * stripe_tile_factor;
 	// Stripe mask value - between 0 (base) and 1 (stripe)
-	args.stripe_mask = texture(stripe_tex, stripe_uv).b;
+	float stripe_mask = texture(stripe_tex, stripe_uv).b;
 
-	args.terrain_uv = 0.5 - unscaled_uv * terrain_tile_factor;
-	vec2 colormap_uv = vec2(uv.x, 1.0 - uv.y);
-	args.land_tint_colour = texture(colormap_land_tex, colormap_uv).rgb;
-	args.water_tint_colour = texture(colormap_water_tex, colormap_uv).rgb;
+	vec2 overlay_uv = vec2(uv_map_pixels.x, map_size.y - uv_map_pixels.y) * overlay_tile_factor;
+	// Parchment overlay colour
+	vec3 overlay_colour = texture(overlay_tex, overlay_uv).rgb;
 
-	return mix(
-		mix(get_terrain_colour(args, vec2(-1, -1)), get_terrain_colour(args, vec2(+1, -1)), pixel_offset.x),
-		mix(get_terrain_colour(args, vec2(-1, +1)), get_terrain_colour(args, vec2(+1, +1)), pixel_offset.x),
-		pixel_offset.y
-	);
+	// Current province index as a pair of byte coordinates and as a combined 16 bit value
+	uvec2 province_data = read_uvec3(uv).xy;
+	uint province_index = uvec2_to_uint(province_data);
+
+	// Get base and stripe colours for province at the current position
+	province_data.x *= 2u; // Double "x coordinate" as colours come in (base, stripe) pairs
+	vec4 province_base_colour = texelFetch(province_colour_tex, ivec2(province_data), 0);
+	province_data.x += 1u; // Add 1 to "x coordinate" to move from base to strip colour
+	vec4 province_stripe_colour = texelFetch(province_colour_tex, ivec2(province_data), 0);
+	// Blend the base and stripe colours according to the current position's stripe mask value
+	vec4 province_colour = mix(province_base_colour, province_stripe_colour, stripe_mask);
+	// Darken the province colour
+	province_colour.rgb -= 0.7;
+
+	// Rec.709 luma coefficients
+	const vec3 luma_weights = vec3(0.2126, 0.7152, 0.0722);
+	float terrain_luma = dot(terrain_colour, luma_weights);
+
+	// Near colour is either the terrain's luma component tinted with the province colour and brightened,
+	// or the normal terrain colour
+	vec3 near_province_colour = mix(vec3(terrain_luma), province_colour.rgb, 0.3) * 1.5;
+	vec3 near_colour = mix(near_province_colour, terrain_colour, float(province_colour.a == 0.0));
+
+	// Far colour is either the province colour mixed with the overlay texture, tinted with the overlay colormap and brightened,
+	// or the normal terrain colour mixed with the overlay texture (primarily for water)
+	vec3 far_province_colour = mix_overlay(overlay_colour, province_colour.rgb);
+	far_province_colour = mix(overlay_tint_colour, far_province_colour, 0.3) * 1.5;
+	vec3 far_terrain_colour = mix_overlay(overlay_colour, terrain_colour);
+	vec3 far_colour = mix(far_province_colour, far_terrain_colour, float(province_colour.a == 0.0));
+
+	// Blend the near (detailed terrain) and far (parchment) colours according to the parchment mix factor (0 for near, 1 for far)
+	vec3 final_colour = mix(near_colour, far_colour, parchment_mix);
+
+	// Significantly brighted the colour if it is hovered over and/or selected, but not if it has province index 0 (all invalid pixels)
+	const vec3 highlight_colour = vec3(1.0);
+	float highlight_mix_val = 0.4 * (float(province_index == hover_index) + float(province_index == selected_index)) * float(province_index != 0u);
+	vec3 highlighted_colour = mix(final_colour, highlight_colour, highlight_mix_val);
+
+	return highlighted_colour;
 }
 
 // Convert from standard RGB to linear colour space (Godot requires the output to be linear)
@@ -119,5 +159,8 @@ vec3 srgb_to_linear(vec3 srgb) {
 }
 
 void fragment() {
+
+	// TODO - add borders, coastlines, rivers, fog of war
+
 	ALBEDO = srgb_to_linear(get_map_colour(UV));
 }