diff options
Diffstat (limited to 'fog.cginc')
| -rw-r--r-- | fog.cginc | 60 |
1 files changed, 43 insertions, 17 deletions
@@ -11,6 +11,8 @@ struct FogParams { float3 color; + float direct_light_intensity; + float indirect_light_intensity; float steps; float y_cutoff; texture2D dithering_noise; @@ -97,11 +99,11 @@ FogResult raymarched_fog(v2f i, FogParams p) // Get intersection with plane at elevation y. float plane_y = p.y_cutoff; - float distance_to_y = 1E3; + float distance_to_y = 1E5; if (abs(rd.y) > 1E-6) { float t = (plane_y - ro.y) / rd.y; if (t > 0) { - distance_to_y = min(t, 1E3); + distance_to_y = min(t, 1E5); } } linearZ = min(linearZ, distance_to_y); @@ -113,6 +115,16 @@ FogResult raymarched_fog(v2f i, FogParams p) const float frame = ((float) AudioLinkData(ALPASS_GENERALVU + int2(1, 0)).x); dither = frac(dither + PHI * frame); + // ----------------------------------------------------------------------- + // Loop-invariant values + float inv_mean_free_path = 1.0 / max(p.mean_free_path, 1e-4); + float turb_lo = 1.0 - 0.5 * p.turbulence; + float turb_hi = 1.0 + 0.5 * p.turbulence; + float3 time_offset = _Time[0] * p.velocity; + + // Golden-ratio LCG seed + float dither_seq = frac(dither + PHI); + // Exponential stepping parameters float step_size = p.step_size; float step_growth = p.step_growth; @@ -128,7 +140,7 @@ FogResult raymarched_fog(v2f i, FogParams p) for (uint ii = 0; ii < p.steps && traveled < max_dist; ++ii) { // Apply dithering to this step - float cur_dither = frac(dither + (ii + 1) * PHI); + float cur_dither = dither_seq; float dithered_step = step_size * (cur_dither + 0.5); float remaining = max_dist - traveled; remaining = max(remaining, 0.1); @@ -139,42 +151,52 @@ FogResult raymarched_fog(v2f i, FogParams p) traveled += dithered_step; // --- Density ---------------------------------------------------------- - float3 noise_coord = (pp + _Time[0] * p.velocity) * p.density_noise_scale.xyz; + float3 noise_coord = (pp + time_offset) * p.density_noise_scale.xyz; float noise_sample = p.density_noise.SampleLevel(bilinear_repeat_s, noise_coord, 0).r; - float noise_factor = lerp(1.0 - 0.5 * p.turbulence, 1.0 + 0.5 * p.turbulence, noise_sample); + float fbm_f = 2.0f; + float fbm_a = 0.5f; + noise_sample += p.density_noise.SampleLevel(bilinear_repeat_s, noise_coord * fbm_f, 0).r * fbm_a; + fbm_f *= 2.0f; + fbm_a *= 0.5f; + noise_sample += p.density_noise.SampleLevel(bilinear_repeat_s, noise_coord * fbm_f, 0).r * fbm_a; + noise_sample *= 0.55f; + + noise_sample *= noise_sample; + + float noise_factor = lerp(turb_lo, turb_hi, noise_sample); float height_factor = exp(-max(pp.y - p.height_offset, 0.0) / p.height_scale); - float sigma_t = noise_factor * height_factor / max(p.mean_free_path, 1e-4); + float sigma_t = noise_factor * height_factor * inv_mean_free_path; float sigma_s = sigma_t * p.albedo; // Analytic integration over the segment float exp_term = exp(-sigma_t * dithered_step); - // If the segment is almost transparent, skip expensive work - if (sigma_t < 1e-6) - { - T *= exp_term; - continue; - } - // --- Incoming radiance ------------------------------------------------ float3 L_in; #if defined(_RAYMARCHED_FOG_EMITTER_TEXTURE) L_in = getEmitterData(p, pp); #else - // Indirect from SH / light volumes +#if 1 + float3 l00 = LightVolumeSH_L0(pp); + float3 l01r = 0; + float3 l01g = 0; + float3 l01b = 0; +#else float3 l00, l01r, l01g, l01b; LightVolumeSH(pp, l00, l01r, l01g, l01b); +#endif float3 indirect = LightVolumeEvaluate(float3(0, 1, 0), l00, l01r, l01g, l01b); // Direct from the dominant realtime light float3 to_light = (_WorldSpaceLightPos0.w == 0.0) ? normalize(_WorldSpaceLightPos0.xyz) : normalize(_WorldSpaceLightPos0.xyz - pp); - float phase = PhaseHG(dot(to_light, -rd), p.g); + float phase = PhaseHG(dot(to_light, rd), p.g); float3 direct = _LightColor0.rgb * phase; - L_in = (direct + indirect) * p.color; + L_in = (direct * p.direct_light_intensity + + indirect * p.indirect_light_intensity) * p.color; #endif // --- Accumulate radiance --------------------------------------------- @@ -185,9 +207,13 @@ FogResult raymarched_fog(v2f i, FogParams p) T *= exp_term; // Early exit if virtually opaque - if (T < 1e-3) + if (T < 1e-7) break; + // Advance LCG for the next step + dither_seq += PHI; + if (dither_seq >= 1.0) dither_seq -= 1.0; + // Grow step size exponentially step_size *= step_growth; } |