Merge pull request #193 from OpenVicProject/map-colours

Improved province colouring and terrain texture tiling

2 files changed, 75 insertions, 55 deletions

diff --git a/game/src/Game/GameSession/MapView.gd b/game/src/Game/GameSession/MapView.gd
index 499f745..838a19a 100644
--- a/game/src/Game/GameSession/MapView.gd
+++ b/game/src/Game/GameSession/MapView.gd
@@ -66,12 +66,7 @@ func _ready() -> void:
 		return
 	_map_shader_material = map_material
 
-	if not _map_mesh_instance.mesh is MapMesh:
-		push_error("Invalid map mesh class: ", _map_mesh_instance.mesh.get_class(), "(expected MapMesh)")
-		return
-	_map_mesh = _map_mesh_instance.mesh
-
-	const pixels_per_terrain_tile : float = 20.0
+	const pixels_per_terrain_tile : float = 16.0
 	_map_shader_material.set_shader_parameter(GameLoader.ShaderManager.param_terrain_tile_factor,
 		float(GameSingleton.get_map_height()) / pixels_per_terrain_tile)
 
@@ -79,6 +74,13 @@ func _ready() -> void:
 	_map_shader_material.set_shader_parameter(GameLoader.ShaderManager.param_stripe_tile_factor,
 		float(GameSingleton.get_map_height()) / pixels_per_stripe_tile)
 
+	if not _map_mesh_instance.mesh is MapMesh:
+		push_error("Invalid map mesh class: ", _map_mesh_instance.mesh.get_class(), "(expected MapMesh)")
+		return
+	_map_mesh = _map_mesh_instance.mesh
+
+	_map_mesh.set_aspect_ratio(GameSingleton.get_map_aspect_ratio())
+
 	# Get map mesh bounds
 	var map_mesh_aabb : AABB = _map_mesh.get_core_aabb() * _map_mesh_instance.transform
 	_map_mesh_corner = Vector2(
diff --git a/game/src/Game/GameSession/TerrainMap.gdshader b/game/src/Game/GameSession/TerrainMap.gdshader
index 97b20e4..487401f 100644
--- a/game/src/Game/GameSession/TerrainMap.gdshader
+++ b/game/src/Game/GameSession/TerrainMap.gdshader
@@ -4,102 +4,120 @@ render_mode unshaded;
 
 #include "res://src/Game/GameSession/ProvinceIndexSampler.gdshaderinc"
 
+// The samplers below do not have the source_color hint because we do not want them
+// to be converted from sRGB to linear colour space, we do that manually at the end.
+
 // Province colour texture
-uniform sampler2D province_colour_tex: source_color, repeat_enable, filter_nearest;
+uniform sampler2D province_colour_tex: repeat_enable, filter_nearest;
 // Index of the mouse over the map mesh
 uniform uint hover_index;
 // Index of the currently selected province
 uniform uint selected_index;
 // Cosmetic terrain textures
-uniform sampler2DArray terrain_tex: source_color, repeat_enable, filter_linear;
+uniform sampler2DArray terrain_tex: repeat_enable, filter_linear;
 // The number of times the terrain textures should tile vertically
 uniform float terrain_tile_factor;
 // Map stripe mask texture
-uniform sampler2D stripe_tex: source_color, repeat_enable, filter_linear;
+uniform sampler2D stripe_tex: repeat_enable, filter_linear;
 // The number of times the stripe texture should tile vertically
 uniform float stripe_tile_factor;
 // Land map tint
-uniform sampler2D colormap_land_tex: source_color, repeat_enable, filter_linear;
+uniform sampler2D colormap_land_tex: repeat_enable, filter_linear;
 // Water map tint
-uniform sampler2D colormap_water_tex: source_color, repeat_enable, filter_linear;
+uniform sampler2D colormap_water_tex: repeat_enable, filter_linear;
 
 const vec3 highlight_colour = vec3(1.0);
-
-vec3 get_terrain_colour(
-	vec2 uv, vec2 corner, vec2 half_pixel_size, // Components for calculating province sampling UV
-	float stripe_mask, // Stripe mask value - between 0 (base) and 1 (stripe)
-	vec2 terrain_uv, // UV coordinates scaled for terrain texture tiling
-	vec3 land_tint_colour, vec3 water_tint_colour // Colours for tinting terrain
-) {
-
-	uvec3 province_data = read_uvec3(fma(corner, half_pixel_size, uv));
+// 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)
+	vec2 terrain_uv; // UV coordinates scaled for terrain texture tiling
+	vec3 land_tint_colour, water_tint_colour; // Colours for tinting 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);
+
+	// 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);
-	vec4 province_colour = mix(province_base_colour, province_stripe_colour, stripe_mask);
+	// 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);
 
-	vec3 terrain_colour = texture(terrain_tex, vec3(terrain_uv, float(terrain_index))).rgb;
-	vec3 tint_colour = mix(land_tint_colour, water_tint_colour, float(terrain_index == 0u));
-	vec3 tinted_terrain_colour = mix(terrain_colour, tint_colour, 0.3);
-	vec3 mixed_colour = mix(tinted_terrain_colour, province_colour.rgb, province_colour.a);
+	// 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;
 
-	float highlight_mix_val = 0.4 * (float(province_index == hover_index) + float(province_index == selected_index));
+	// 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));
+
+	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);
 }
 
 // Rescale UV coordinates to remove squashing caused by normalisation
-vec2 denormalise(vec2 uv, vec2 dims) {
+vec2 denormalise(const vec2 uv, const vec2 dims) {
 	return vec2(uv.x * dims.x / dims.y, uv.y);
 }
 
-vec3 mix_terrain_colour(vec2 uv) {
+// 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;
+
 	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);
-	vec2 half_pixel_size = 0.49 / map_size;
+	args.half_pixel_size = 0.49 / map_size;
 
 	// UV coords adjusted to remove squashing caused by normalisation relative to map dimensions
 	vec2 unscaled_uv = denormalise(uv, map_size);
 
 	vec2 stripe_uv = unscaled_uv * stripe_tile_factor;
 	// Stripe mask value - between 0 (base) and 1 (stripe)
-	float stripe_mask = texture(stripe_tex, stripe_uv).b;
+	args.stripe_mask = texture(stripe_tex, stripe_uv).b;
 
-	vec2 terrain_uv = unscaled_uv * terrain_tile_factor;
+	args.terrain_uv = 0.5 - unscaled_uv * terrain_tile_factor;
 	vec2 colormap_uv = vec2(uv.x, 1.0 - uv.y);
-	vec3 colormap_land_colour = texture(colormap_land_tex, colormap_uv).rgb;
-	vec3 colormap_water_colour = texture(colormap_water_tex, colormap_uv).rgb;
+	args.land_tint_colour = texture(colormap_land_tex, colormap_uv).rgb;
+	args.water_tint_colour = texture(colormap_water_tex, colormap_uv).rgb;
 
 	return mix(
-		mix(
-			get_terrain_colour(
-				uv, vec2(-1, -1), half_pixel_size, stripe_mask,
-				terrain_uv, colormap_land_colour, colormap_water_colour
-			),
-			get_terrain_colour(
-				uv, vec2(+1, -1), half_pixel_size, stripe_mask,
-				terrain_uv, colormap_land_colour, colormap_water_colour
-			), pixel_offset.x
-		),
-		mix(
-			get_terrain_colour(
-				uv, vec2(-1, +1), half_pixel_size, stripe_mask,
-				terrain_uv, colormap_land_colour, colormap_water_colour
-			),
-			get_terrain_colour(
-				uv, vec2(+1, +1), half_pixel_size, stripe_mask,
-				terrain_uv, colormap_land_colour, colormap_water_colour
-			), pixel_offset.x
-		),
+		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
 	);
 }
 
+// Convert from standard RGB to linear colour space (Godot requires the output to be linear)
+vec3 srgb_to_linear(vec3 srgb) {
+	return mix(
+		srgb * (1.0 / 12.92),
+		pow((srgb + vec3(0.055)) * (1.0 / (1.0 + 0.055)), vec3(2.4)),
+		greaterThan(srgb, vec3(0.04045))
+	);
+}
+
 void fragment() {
-	vec3 terrain_colour = mix_terrain_colour(UV);
-	ALBEDO = terrain_colour;
+	ALBEDO = srgb_to_linear(get_map_colour(UV));
 }