Underwater rendering bug

[XakepSDK]

When you're underwater, game renders ceiling as floor instead of actual ceiling. Water reflections are too mirror-like.

[XakepSDK]

https://puu.sh/CyJ8U/709da3fcab.png

[muddymind]

My guess is that properly casting refraction rays is expensive since they would need a lot of them to reduce noise. They probably just took them out and this also affects glass surfaces which are almost opaque.

[niko1point0]

You’re right, there aren’t refraction rays. I think they should be implemented, regardless if performance drops. The point of this mod is to implement accurate Ray Tracing, therefore I assume its on the developer’s list of things to do

[mastan-rus]

Since engine uses raytracing, it can do proper reflection/refraction. Like in Quake Wars: Ray Traced - see screenshot on the right. Would be great if engine featured switchable water effect:

• Realistic, with total internal reflection etc.
• Like most games do - as if water and air has same refractive index, but with some distortion effect.
• Off or current mirror-like (for performance reasons)

[muddymind]

Looking at src/refresh/vkpt/shader/path_tracer.h

if(is_water(material_id)) {
    vec3 water_normal = waterd(position.xy * 0.1).xzy;
    float F = pow(1.0 - max(0.0, -dot(direction, water_normal)), 5.0);
    direction = reflect(direction, water_normal);
    trace_ray(Ray(position, direction, 0.01, 10000.0));
    throughput *= mix(vec3(0.1, 0.1, 0.15), vec3(1.0), F);
    contrib += (1.0 - F) * vec3(0.2, 0.4, 0.4) * 0.5;

    if(!found_intersection(ray_payload_brdf))
    {
        primary_albedo = env_map(direction); // * throughput;
        store_no_hit(primary_albedo, motion);
        return vec4(contrib, false);
    }

    Triangle triangle = get_hit_triangle(ray_payload_brdf);
    vec3 bary         = get_hit_barycentric(ray_payload_brdf);
    vec2 tex_coord    = triangle.tex_coords * bary;

    /* world-space */
    position       = triangle.positions * bary;
    normal         = normalize(triangle.normals * bary);
    material_id    = triangle.material_id;
    albedo         = global_textureLod(triangle.material_id, tex_coord, 2).rgb * ALBEDO_MULT;
    cluster_idx    = triangle.cluster;
    primary_albedo = albedo;
    albedo         = vec3(1);

    temporal_accum = true;

    if(dot(direction, normal) > 0)
        normal = -normal;
}

Looking at this it appears it only calculates the reflection ray.

[niko1point0]

Only reflection was implemented. Refraction has not been implemented yet, just like particle effects. Give it time, the developers will work on it

[IvanVolosyuk]

I have implemented fresnel reflections and refractions in the fork: https://github.com/IvanVolosyuk/q2vkpt In the commit: https://github.com/IvanVolosyuk/q2vkpt/commit/886d97b6ac2dbfb1469b47f60523fda3ef552418 Looks better - more realistics, noisier as well.