fix river water direction2

core/biome_generator/biome_generator.gd

@@ -8,6 +8,19 @@ const CHUNK_GENERATION_STEPS_PER_FRAME: int = 2
 const CHUNK_CLEANUP_STEPS_PER_FRAME: int = 4
 const LAMPPOST_WIRE_STEPS_PER_FRAME: int = 1
 const RAILWAY_SCENE_DIRECTORY: String = "res://tgcc/chunk/railway/scene"
+const RIVER_SIDE_ORDER: Array[String] = ["north", "est", "south", "west"]
+const RIVER_DIRECTIONS: Dictionary = {
+	"north": Vector2(0.0, -1.0),
+	"est": Vector2(1.0, 0.0),
+	"south": Vector2(0.0, 1.0),
+	"west": Vector2(-1.0, 0.0),
+}
+const RIVER_NEIGHBOUR_OFFSETS: Dictionary = {
+	"north": Vector2i(0, -1),
+	"est": Vector2i(1, 0),
+	"south": Vector2i(0, 1),
+	"west": Vector2i(-1, 0),
+}
 
 @export_group("Rails")
 @export var rail_path: Path3D 
@@ -617,10 +630,14 @@ func _add_compatible_biome(grid_pos: Vector2i) -> void:
 		if info_new != null and "have_lamppost" in info_new:
 			have_lamppost = info_new.have_lamppost
 
+		var river_flow_direction = _calculate_river_flow_direction(grid_pos, choise.data["river_connections"])
+		_apply_river_flow_direction(new_chunk, river_flow_direction)
+			
 		board[grid_pos] = {
 			"type": "bioma", 
 			"exit": choise.data["connections"], 
 			"river_exit": choise.data["river_connections"],
+			"river_flow_direction": river_flow_direction,
 			"heights": choise.data["heights"], 
 			"node": new_chunk, 
 			"info": info_new,
@@ -647,12 +664,109 @@ func _add_compatible_biome(grid_pos: Vector2i) -> void:
 			"type": "biome", 
 			"exit": {"north":false, "est":false, "south":false, "west":false}, 
 			"river_exit": {"north":false, "est":false, "south":false, "west":false},
+			"river_flow_direction": Vector2.ZERO,
 			"heights": safe_heights, 
 			"node": backup,
 			"info": info_backup,
 			"have_lamppost": false
 		}
 
+func _calculate_river_flow_direction(grid_pos: Vector2i, river_connections: Dictionary) -> Vector2:
+	var connected_sides: Array[String] = []
+	for side in RIVER_SIDE_ORDER:
+		if river_connections.has(side) and river_connections[side]:
+			connected_sides.append(side)
+
+	if connected_sides.is_empty():
+		return Vector2.ZERO
+
+	var neighbour_flow = _get_connected_neighbour_river_flow(grid_pos, connected_sides)
+	if not neighbour_flow.is_zero_approx():
+		var continued_flow = _continue_river_flow_from_neighbour(grid_pos, connected_sides, neighbour_flow)
+		if not continued_flow.is_zero_approx():
+			return continued_flow.normalized()
+
+	var default_flow = _get_default_river_flow(connected_sides)
+	if default_flow.is_zero_approx():
+		return Vector2.ZERO
+	return default_flow.normalized()
+
+func _get_connected_neighbour_river_flow(grid_pos: Vector2i, connected_sides: Array[String]) -> Vector2:
+	for side in connected_sides:
+		var neighbour_pos: Vector2i = grid_pos + RIVER_NEIGHBOUR_OFFSETS[side]
+		if not board.has(neighbour_pos):
+			continue
+		var neighbour = board[neighbour_pos]
+		if not neighbour.has("river_flow_direction"):
+			continue
+		var neighbour_flow: Vector2 = neighbour["river_flow_direction"]
+		if not neighbour_flow.is_zero_approx():
+			return neighbour_flow.normalized()
+	return Vector2.ZERO
+
+func _continue_river_flow_from_neighbour(grid_pos: Vector2i, connected_sides: Array[String], neighbour_flow: Vector2) -> Vector2:
+	for side in connected_sides:
+		var neighbour_pos: Vector2i = grid_pos + RIVER_NEIGHBOUR_OFFSETS[side]
+		if not board.has(neighbour_pos):
+			continue
+		var neighbour = board[neighbour_pos]
+		if not neighbour.has("river_flow_direction"):
+			continue
+		var side_direction: Vector2 = RIVER_DIRECTIONS[side]
+		var neighbour_direction: Vector2 = neighbour["river_flow_direction"]
+		if neighbour_direction.is_zero_approx():
+			continue
+		neighbour_direction = neighbour_direction.normalized()
+		var other_sides = connected_sides.duplicate()
+		other_sides.erase(side)
+		if other_sides.is_empty():
+			return neighbour_direction
+
+		var other_direction = _get_average_river_side_direction(other_sides)
+		if neighbour_direction.dot(-side_direction) > 0.25:
+			return other_direction - side_direction
+		if neighbour_direction.dot(side_direction) > 0.25:
+			return side_direction - other_direction
+
+	var default_flow = _get_default_river_flow(connected_sides)
+	if default_flow.dot(neighbour_flow) < 0.0:
+		return -default_flow
+	return default_flow
+
+func _get_default_river_flow(connected_sides: Array[String]) -> Vector2:
+	if connected_sides.size() == 1:
+		return RIVER_DIRECTIONS[connected_sides[0]]
+
+	if connected_sides.has("north") and connected_sides.has("south"):
+		return Vector2(0.0, 1.0)
+	if connected_sides.has("est") and connected_sides.has("west"):
+		return Vector2(1.0, 0.0)
+
+	var start_direction: Vector2 = RIVER_DIRECTIONS[connected_sides[0]]
+	var end_direction = _get_average_river_side_direction(connected_sides.slice(1))
+	return end_direction - start_direction
+
+func _get_average_river_side_direction(sides: Array[String]) -> Vector2:
+	var direction := Vector2.ZERO
+	for side in sides:
+		direction += RIVER_DIRECTIONS[side]
+	if direction.is_zero_approx():
+		return Vector2.ZERO
+	return direction / float(sides.size())
+
+func _apply_river_flow_direction(root: Node, flow_direction: Vector2) -> void:
+	if flow_direction.is_zero_approx():
+		return
+	_set_river_flow_direction_recursive(root, flow_direction.normalized())
+
+func _set_river_flow_direction_recursive(node: Node, flow_direction: Vector2) -> void:
+	if node is MeshInstance3D and node.name.begins_with("Water_F"):
+		var mesh_instance := node as MeshInstance3D
+		mesh_instance.set_instance_shader_parameter("river_flow_direction", flow_direction)
+
+	for child in node.get_children():
+		_set_river_flow_direction_recursive(child, flow_direction)
+
 func _needed_connection(near_pos: Vector2i, side_needed: String) -> int:
 	if not board.has(near_pos): 
 		_register_cell_with_ray(near_pos)

core/daynight/water_river.gdshader

@@ -32,9 +32,6 @@ uniform float foam_roughness : hint_range(0.0, 1.0, 0.01) = 0.05;
 
 group_uniforms Wave;
 uniform sampler2D wave_texture;
-#if !USE_UNSHADED
-	uniform sampler2D wave_normal_texture;
-#endif
 uniform float wave_softness : hint_range(0.0, 10.0, 0.1) = 3.0;
 uniform vec2 wave_scale = vec2(0.2);
 uniform vec2 wave_layer_scale = vec2(1.5);
@@ -42,6 +39,7 @@ uniform float wave_highlight : hint_range(0.0, 1.0, 0.05) = 0.5;
 
 group_uniforms Wave.Motion;
 uniform vec2 wave_velocity = vec2(0.02);
+instance uniform vec2 river_flow_direction = vec2(0.0, 0.0);
 
 group_uniforms Foam;
 uniform sampler2D foam_texture;
@@ -72,6 +70,7 @@ uniform float foam_exponent = 2.0;
 
 uniform sampler2D screen_texture : hint_screen_texture;
 varying vec3 world_pos;
+varying vec2 world_wave_velocity;
 
 #if USE_CAUSTICS
 	vec3 sample_caustics(vec2 uv){
@@ -103,17 +102,47 @@ vec4 sample_wave(sampler2D tex, vec2 uv, vec2 velocity, float lod){
 	return wave2;
 }
 
+vec3 sample_wave_normal(vec2 uv, vec2 velocity, float center_wave) {
+	vec2 normal_offset = vec2(0.25, 0.0);
+	float wave_x = sample_wave(wave_texture, uv + normal_offset.xy, velocity, wave_softness).r;
+	float wave_z = sample_wave(wave_texture, uv + normal_offset.yx, velocity, wave_softness).r;
+	vec2 slope = vec2(center_wave - wave_x, center_wave - wave_z) * 0.35;
+	return normalize(vec3(slope, 1.0)) * 0.5 + 0.5;
+}
+
+vec2 get_world_wave_velocity(mat4 model_matrix) {
+	float velocity_length = length(wave_velocity);
+	if (velocity_length <= 0.0001) {
+		return vec2(0.0);
+	}
+
+	float flow_direction_length = length(river_flow_direction);
+	if (flow_direction_length > 0.0001) {
+		return (river_flow_direction / flow_direction_length) * velocity_length;
+	}
+
+	vec3 world_direction_3d = (model_matrix * vec4(0.0, 1.0, 0.0, 0.0)).xyz;
+	vec2 world_direction = world_direction_3d.xz;
+	float world_direction_length = length(world_direction);
+	if (world_direction_length <= 0.0001) {
+		return wave_velocity;
+	}
+
+	return (world_direction / world_direction_length) * velocity_length;
+}
+
 void vertex(){
 	world_pos = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
+	world_wave_velocity = get_world_wave_velocity(MODEL_MATRIX);
 	
 	#if USE_DISPLACEMENT
-		float wave = sample_wave(wave_texture, world_pos.xz, wave_velocity, wave_softness).r;
+		float wave = sample_wave(wave_texture, world_pos.xz, world_wave_velocity, wave_softness).r;
 		VERTEX.y += wave*displacement_amount;
 	#endif
 }
 
 void fragment() {
-	float wave = sample_wave(wave_texture, world_pos.xz, wave_velocity, wave_softness).r;
+	float wave = sample_wave(wave_texture, world_pos.xz, world_wave_velocity, wave_softness).r;
 	wave = smoothstep(0.0,1.0,wave);
 	
 	vec2 screen_uv = SCREEN_UV;
@@ -141,8 +170,8 @@ void fragment() {
 	
 	// Caustics
 	#if USE_CAUSTICS
-		vec3 caustics1 = sample_caustics(surface_uv + (TIME * -wave_velocity));
+		vec3 caustics1 = sample_caustics(surface_uv + (TIME * -world_wave_velocity));
-		vec3 caustics2 = sample_caustics((surface_uv + (caustics1.r*0.05)) + (TIME * (wave_velocity*0.5)));
+		vec3 caustics2 = sample_caustics((surface_uv + (caustics1.r*0.05)) + (TIME * (world_wave_velocity*0.5)));
 		vec3 caustics = caustics2 * (1.0 - depth);
 	#endif
 	
@@ -170,7 +199,7 @@ void fragment() {
 	color = mix(color, foam_color.rgb, foam);
 	
 	#if !USE_UNSHADED
-		vec3 wave_normal_map = sample_wave(wave_normal_texture, world_pos.xz, wave_velocity, wave_softness).rgb;
+		vec3 wave_normal_map = sample_wave_normal(world_pos.xz, world_wave_velocity, wave);
 		NORMAL_MAP = wave_normal_map;
 	#endif