feat: water effects (#19)

* feat(shaders): add lighting to block accumulation OIT shaders

* feat(renderer): add water rendering with OIT and new shaders

* feat(water): implement screen-space reflection and refraction for water with depth fade and perturbation

* refactor(shader): replace glUniform calls with generic set_loc and remove cached locations

* feat(water): add noise-based caustics and configurable fog density

* fix(water shader): update depth fade and remove underwater check

- Increase DEPTH_FADE_DISTANCE from 8 to 10
- Remove conditional so depth fade always applies
- Darken deepColor from (0, 0.08, 0.15) to (0, 0.015, 0.045)

* feat(underwater): add volume scattering and shadow mapping for light shafts

assets/shaders/under_water_v_shader.glsl

@@ -3,9 +3,18 @@
 layout (location = 0) in vec2 pos;
 layout (location = 1) in vec2 texCoord;
 
-out vec2 TexCoord;
+uniform mat4 InverseViewProjection; 
+uniform vec3 cameraPos;
 
+out vec2 TexCoord;
+out vec3 rayDir;
 void main() {
-    gl_Position = vec4(pos.x, pos.y, 0.0, 1.0);
     TexCoord = texCoord;
+    vec4 clipPos = vec4(pos, 1.0, 1.0);
+    vec4 worldPosH = InverseViewProjection * clipPos;
+    vec3 worldPos = worldPosH.xyz / worldPosH.w;
+    vec3 RayDir = worldPos - cameraPos;
+    rayDir = normalize(RayDir);
+    gl_Position = clipPos;
+    
 }