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xash3d-fwgs
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vk: rt: invert pdf for point lights 

This makes math even more stable, but it removes imprecisions that were accidentally helping the rendered image. Thus it looks a bit darker.
Fixing that would need proper sampling, with disc angle and what not.
This commit is contained in:
Ivan 'provod' Avdeev 2024-01-11 11:36:35 -05:00
parent dd17dee35d
commit 02afc7b320
1 changed files with 9 additions and 7 deletions
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16
ref/vk/shaders/light.glsl
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@ -41,6 +41,7 @@ void computePointLights(vec3 P, vec3 N, uint cluster_index, vec3 view_dir, Mater
if (light_dot < 1e-5)
continue;
// TODO split into separate spotlihgts and point lights arrays
const float spot_dot = -dot(light_dir_norm, dir);
const float stopdot2 = lights.m.point_lights[i].dir_stopdot2.a;
if (spot_dot < stopdot2)
@ -57,8 +58,8 @@ void computePointLights(vec3 P, vec3 N, uint cluster_index, vec3 view_dir, Mater
__LINE__, spot_dot, stopdot, stopdot2, spot_attenuation);
}
#endif
const float kSpotAttenuationThreshold = 1e-3;
if (spot_attenuation < kSpotAttenuationThreshold)
// Skip the rest of the computation for points completely outside of the light cone
if (spot_attenuation <= 0.)
continue;
}
@ -93,14 +94,15 @@ void computePointLights(vec3 P, vec3 N, uint cluster_index, vec3 view_dir, Mater
// d2=4489108.500000 r2=1.000000 dist=2118.751465 spot_attenuation=0.092902 INVALID pdf=-316492608.000000
// Therefore, need to clamp denom with max
const float pdf = 1. / (max(1e-4, 1. - sqrt(d2 - r2) / dist) * spot_attenuation);
// TODO need better sampling right nao
const float one_over_pdf = max(0., 1. - sqrt(d2 - r2) / dist) * spot_attenuation;
#ifdef DEBUG_VALIDATE_EXTRA
if (IS_INVALID(pdf) || pdf <= 0.) {
debugPrintfEXT("light.glsl:%d d2=%f r2=%f dist=%f spot_attenuation=%f INVALID pdf=%f",
__LINE__, d2, r2, dist, spot_attenuation, pdf);
if (IS_INVALID(one_over_pdf) || one_over_pdf < 0.) {
debugPrintfEXT("light.glsl:%d d2=%f r2=%f dist=%f spot_attenuation=%f INVALID one_over_pdf=%f",
__LINE__, d2, r2, dist, spot_attenuation, one_over_pdf);
}
#endif
color /= pdf;
color *= one_over_pdf;
}
// if (dot(color,color) < color_culling_threshold)