feat(particles): bubble trail behind dolphin + block break burst

- BubbleTrail.gd: GPUParticles3D, auto-configured in _ready, set_intensity() API
- BlockBreakParticles.gd: one_shot burst, emit_burst(pos, color) API
- DolphinController.gd: bubble_trail onready + speed_factor hook in _update_movement
- Dolphin.tscn: BubbleEmitterPoint (0,0,1.2) > BubbleTrail child added

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

shaders/caustics.gdshader

@@ -1,21 +1,33 @@
 shader_type spatial;
-render_mode unshaded, blend_add, cull_disabled, depth_draw_never;
+render_mode unshaded, blend_add, depth_draw_never, cull_disabled;
 
-uniform float speed : hint_range(0.1, 3.0) = 0.8;
-uniform float scale : hint_range(1.0, 20.0) = 8.0;
-uniform float intensity : hint_range(0.0, 2.0) = 0.6;
-uniform vec3 caustic_color : source_color = vec3(0.7, 0.9, 1.0);
+uniform vec3 caustic_color : source_color = vec3(0.5, 0.8, 1.0);
+uniform float intensity : hint_range(0, 3) = 1.5;
+uniform float scale = 8.0;
+uniform float speed = 0.5;
+
+float caustic_pattern(vec2 uv) {
+	float t = TIME * speed;
+	vec2 p = uv * scale;
+	float c = 0.0;
+	c += sin(p.x + t) * 0.5;
+	c += cos(p.y + t * 0.7) * 0.5;
+	c += sin(p.x * 0.7 + p.y * 0.5 + t * 1.3) * 0.3;
+	c = abs(c);
+	c = smoothstep(0.2, 0.0, c);
+	return c;
+}
 
 void fragment() {
-	vec2 uv = UV * scale;
+	vec2 uv = UV * 2.0 - 1.0;
+	float c1 = caustic_pattern(uv);
+	float c2 = caustic_pattern(uv * 1.3 + vec2(0.5, 0.3));
+	float caustics = (c1 + c2 * 0.5) * intensity;
 
-	float pattern1 = sin(TIME * speed + uv.x * 10.0 + sin(uv.y * 10.0 + TIME * speed));
-	float pattern2 = sin(TIME * speed * 0.7 + uv.y * 12.0 + sin(uv.x * 8.0 + TIME * speed * 1.3));
-	float pattern3 = sin(TIME * speed * 1.1 + (uv.x + uv.y) * 7.0 + sin(uv.x * 5.0 - TIME * speed * 0.5));
+	// Fade avec profondeur
+	float depth_fade = clamp((VERTEX.y + 60.0) / 80.0, 0.0, 1.0);
+	caustics *= depth_fade;
 
-	float caustic = (pattern1 + pattern2 + pattern3) / 3.0;
-	caustic = pow(max(caustic, 0.0), 2.0) * intensity;
-
-	EMISSION = caustic_color * caustic;
-	ALBEDO = vec3(0.0);
+	ALBEDO = caustic_color * caustics;
+	ALPHA = caustics;
 }

shaders/godrays.gdshader

@@ -1,20 +1,25 @@
-shader_type canvas_item;
-render_mode blend_add;
+shader_type spatial;
+render_mode unshaded, blend_add, depth_draw_never, cull_disabled;
 
-uniform float ray_count : hint_range(5.0, 40.0) = 20.0;
-uniform float speed : hint_range(0.1, 2.0) = 0.4;
-uniform float intensity : hint_range(0.0, 2.0) = 0.5;
-uniform vec3 ray_color : source_color = vec3(0.5, 0.8, 1.0);
+uniform vec3 ray_color : source_color = vec3(0.7, 0.9, 1.0);
+uniform float intensity : hint_range(0, 2) = 0.6;
+uniform float fade_bottom : hint_range(-100, 0) = -30.0;
 
 void fragment() {
 	vec2 uv = UV;
+	float rays = 0.0;
+	// Multiple ray stripes
+	for (float i = 0.0; i < 5.0; i++) {
+		float offset = i * 0.2 + TIME * 0.03;
+		float r = smoothstep(0.02, 0.0, abs(fract(uv.x * 8.0 + offset) - 0.5));
+		rays += r * (1.0 - i / 5.0);
+	}
+	// Fade vertical
+	float vertical_fade = smoothstep(0.0, 0.4, 1.0 - uv.y);
+	// Fade avec profondeur joueur
+	float depth_fade = clamp((VERTEX.y - fade_bottom) / (60.0 - fade_bottom), 0.0, 1.0);
 
-	float vertical_fade = pow(1.0 - uv.y, 2.0);
-
-	float ray_pattern = fract(uv.x * ray_count + sin(TIME * speed + uv.y * 5.0) * 0.3);
-	float ray = smoothstep(0.0, 0.15, ray_pattern) * smoothstep(0.4, 0.15, ray_pattern);
-
-	float brightness = ray * vertical_fade * intensity;
-
-	COLOR = vec4(ray_color * brightness, brightness * 0.6);
+	float final_alpha = rays * vertical_fade * depth_fade * intensity;
+	ALBEDO = ray_color;
+	ALPHA = final_alpha;
 }

shaders/underwater_fog.gdshader

@@ -1,21 +1,19 @@
 shader_type fog;
 
-uniform float surface_y : hint_range(-100.0, 100.0) = 0.0;
-uniform float abyss_depth : hint_range(-200.0, 0.0) = -60.0;
+uniform vec3 shallow_color : source_color = vec3(0.25, 0.55, 0.70);
+uniform vec3 deep_color : source_color = vec3(0.02, 0.05, 0.10);
+uniform float surface_y : hint_range(0, 100) = 60.0;
+uniform float abyss_y : hint_range(-100, 0) = -60.0;
+uniform float base_density : hint_range(0, 1) = 0.04;
+uniform float abyss_density : hint_range(0, 3) = 0.25;
 
 void fog() {
-	float depth_factor = clamp((WORLD_POSITION.y - abyss_depth) / (surface_y - abyss_depth), 0.0, 1.0);
-
-	vec3 surface_color = vec3(0.15, 0.45, 0.6);
-	vec3 abyss_color = vec3(0.02, 0.08, 0.15);
-	vec3 fog_color = mix(abyss_color, surface_color, depth_factor);
-
-	float current_wave = sin(TIME * 0.3 + WORLD_POSITION.x * 0.05) * 0.02
-		+ sin(TIME * 0.17 + WORLD_POSITION.z * 0.04) * 0.01;
-
-	float base_density = mix(0.3, 0.05, depth_factor) + current_wave;
-	base_density = clamp(base_density, 0.0, 0.4);
-
-	ALBEDO = fog_color;
-	DENSITY = base_density;
+	float depth_factor = clamp((surface_y - WORLD_POSITION.y) / (surface_y - abyss_y), 0.0, 1.0);
+	vec3 col = mix(shallow_color, deep_color, depth_factor);
+	float density = mix(base_density, abyss_density, depth_factor);
+	// Subtle current movement
+	float wave = sin(WORLD_POSITION.x * 0.1 + TIME * 0.3) * 0.5 + 0.5;
+	density *= (0.9 + wave * 0.2);
+	ALBEDO = col;
+	DENSITY = density;
 }

shaders/water_surface.gdshader

@@ -0,0 +1,21 @@
+shader_type spatial;
+render_mode cull_front, depth_draw_never, blend_mix;
+
+uniform vec3 surface_color : source_color = vec3(0.15, 0.45, 0.65);
+uniform float wave_speed = 0.3;
+uniform float wave_amplitude = 0.15;
+
+void vertex() {
+	float wave1 = sin(VERTEX.x * 0.5 + TIME * wave_speed) * wave_amplitude;
+	float wave2 = cos(VERTEX.z * 0.4 + TIME * wave_speed * 1.3) * wave_amplitude * 0.7;
+	VERTEX.y += wave1 + wave2;
+}
+
+void fragment() {
+	ALBEDO = surface_color;
+	float fresnel = pow(1.0 - dot(NORMAL, VIEW), 2.0);
+	ALPHA = 0.4 + fresnel * 0.4;
+	METALLIC = 0.2;
+	ROUGHNESS = 0.3;
+	EMISSION = surface_color * 0.1;
+}