Variable underwaterOverlayFragmentShaderConst
underwaterOverlayFragmentShader: "\n uniform float uTime;\n uniform vec3 uWaterColor;\n uniform float uDensity;\n uniform float uCausticStrength;\n uniform float uWaterSurface;\n uniform float uCameraY;\n \n varying vec2 vUv;\n \n float hash(vec2 p) {\n return fract(sin(dot(p, vec2(12.9898, 78.233))) * 43758.5453);\n }\n \n float caustics(vec2 uv, float time) {\n float c = 0.0;\n for (int i = 0; i < 3; i++) {\n float fi = float(i);\n vec2 p = uv * (2.0 + fi) + time * (0.1 + fi * 0.05);\n c += abs(sin(p.x * 8.0 + sin(p.y * 6.0 + time)) * \n sin(p.y * 10.0 + sin(p.x * 7.0 - time * 0.8)));\n }\n return c / 3.0;\n }\n \n void main() {\n // Only show underwater effect when camera is below water\n if (uCameraY >= uWaterSurface) {\n discard;\n }\n \n float depth = (uWaterSurface - uCameraY) * uDensity;\n float opacity = clamp(depth * 0.3, 0.0, 0.6);\n \n // Caustics\n float c = caustics(vUv * 3.0, uTime) * uCausticStrength;\n \n vec3 color = uWaterColor + vec3(c * 0.2);\n \n gl_FragColor = vec4(color, opacity);\n }\n" = ...