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Merged
jeffamstutz merged 11 commits into from
Feb 6, 2026
Merged

Improve Light Handling and Rendering Quality #216

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0c02f22
Update visrtx device json
tarcila Nov 15, 2025
973276d
Add raygen_helpers.h include directive to volumeIntegration.h
tarcila Feb 3, 2026
20d3395
Make sure to normalize nextRay direction
tarcila Feb 3, 2026
81908e9
Refactor lights into dual-bucket flatten architecture
tarcila Feb 3, 2026
7d0b057
Fix HDRI instance transform in background evaluation
tarcila Feb 3, 2026
e7e2cb6
Accumulate all visible HDRI contributions for background
tarcila Feb 3, 2026
afac91d
Back to diffuse distilling
tarcila Feb 4, 2026
c3c4144
Update physically_based.mdl so distilling works better
tarcila Feb 5, 2026
7e723b4
Correctly implement transmission approximation for MDL with DirectLight
tarcila Feb 5, 2026
d959f6e
Render the albedo AOV as srgb data
tarcila Nov 14, 2025
08141a5
Let's keep the default sample count to 128 for PT
tarcila Feb 5, 2026
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8 changes: 4 additions & 4 deletions devices/rtx/device/gpu/gpu_objects.h
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Original file line number Diff line number Diff line change
Expand Up @@ -612,9 +612,8 @@ struct InstanceVolumeGPUData

struct InstanceLightGPUData
{
const DeviceObjectIndex *indices;
size_t numLights;
mat4 xfm;
DeviceObjectIndex lightIndex; // Index into registry.lights[]
mat4 xfm; // Transform for this light instance
};

// World //
Expand All @@ -632,7 +631,8 @@ struct WorldGPUData
const InstanceLightGPUData *lightInstances;
size_t numLightInstances;

DeviceObjectIndex hdri;
const InstanceLightGPUData *hdriLightInstances;
size_t numHdriLightInstances;
};

// Renderer //
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28 changes: 22 additions & 6 deletions devices/rtx/device/gpu/gpu_util.h
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Original file line number Diff line number Diff line change
Expand Up @@ -304,12 +304,28 @@ VISRTX_DEVICE vec4 getBackgroundImage(
VISRTX_DEVICE vec4 getBackground(
const FrameGPUData &fd, const vec2 &loc, const vec3 &rayDir)
{
const LightGPUData *hdri =
fd.world.hdri != -1 ? &fd.registry.lights[fd.world.hdri] : nullptr;
if (hdri && hdri->hdri.visible)
return vec4(sampleHDRI(*hdri, rayDir), 1.f);
else
return getBackgroundImage(fd.renderer, loc);
// Accumulate contributions from all visible HDRI lights
vec3 hdriContribution = vec3(0.f);
bool hasVisibleHDRI = false;

for (size_t i = 0; i < fd.world.numHdriLightInstances; i++) {
const auto &hdriLight = fd.world.hdriLightInstances[i];
const auto &light = fd.registry.lights[hdriLight.lightIndex];
if (light.hdri.visible) {
// Transform ray direction from world space to HDRI local space
// For orthonormal matrices, inverse = transpose
const mat3 xfmInv = glm::transpose(mat3(hdriLight.xfm));
const vec3 localRayDir = xfmInv * rayDir;
hdriContribution += sampleHDRI(light, localRayDir);
hasVisibleHDRI = true;
}
}

if (hasVisibleHDRI)
return vec4(hdriContribution, 1.f);

// No visible HDRI, use background image/color
return getBackgroundImage(fd.renderer, loc);
}

VISRTX_DEVICE uint32_t computeGeometryPrimId(const SurfaceHit &hit)
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1 change: 1 addition & 0 deletions devices/rtx/device/gpu/renderer/raygen_helpers.h
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Expand Up @@ -35,6 +35,7 @@
#include "gpu/intersectRay.h"
#include "gpu/renderer/common.h"
#include "gpu/shadingState.h"
#include "gpu/volumeIntegration.h"

// Shared helper functions for ray generation across renderers

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3 changes: 2 additions & 1 deletion devices/rtx/device/material/shaders/MDLShader_ptx.cu
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Original file line number Diff line number Diff line change
Expand Up @@ -273,7 +273,8 @@ vec3 __direct_callable__evaluateTransmission(
const MDLShadingState *shadingState)
{
return mdlTransmission(
&shadingState->state, &shadingState->resData, shadingState->argBlock);
&shadingState->state, &shadingState->resData, shadingState->argBlock)
* 0.85f;
}

VISRTX_CALLABLE
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153 changes: 75 additions & 78 deletions devices/rtx/device/renderer/DirectLight_ptx.cu
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Original file line number Diff line number Diff line change
Expand Up @@ -39,11 +39,11 @@
#include "gpu/gpu_math.h"
#include "gpu/gpu_objects.h"
#include "gpu/intersectRay.h"
#include "gpu/renderer/common.h"
#include "gpu/renderer/raygen_helpers.h"
#include "gpu/sampleLight.h"
#include "gpu/shadingState.h"
#include "gpu/shading_api.h"
#include "gpu/renderer/common.h"
#include "gpu/renderer/raygen_helpers.h"

namespace visrtx {

Expand All @@ -53,43 +53,41 @@ DECLARE_FRAME_DATA(frameData)

struct DirectLightShadingPolicy
{
static VISRTX_DEVICE vec4 shadeSurface(const MaterialShadingState &shadingState,
ScreenSample &ss,
const Ray &ray,
const SurfaceHit &hit)
{
const auto &rendererParams = frameData.renderer;
const auto &directLightParams = rendererParams.params.directLight;

auto &world = frameData.world;

// Compute ambient light contribution //
const float aoFactor = directLightParams.aoSamples > 0
? computeAO(ss,
ray,
hit,
rendererParams.occlusionDistance,
directLightParams.aoSamples,
&surfaceAttenuation)
: 1.f;

vec3 contrib = materialEvaluateEmission(shadingState, -ray.dir);

// Handle ambient light contribution
if (rendererParams.ambientIntensity > 0.0f) {
contrib += rendererParams.ambientColor * rendererParams.ambientIntensity
* materialEvaluateTint(shadingState);
}

// Handle all lights contributions
for (size_t i = 0; i < world.numLightInstances; i++) {
auto *inst = world.lightInstances + i;
if (!inst)
continue;
static VISRTX_DEVICE vec4 shadeSurface(
const MaterialShadingState &shadingState,
ScreenSample &ss,
const Ray &ray,
const SurfaceHit &hit)
{
const auto &rendererParams = frameData.renderer;
const auto &directLightParams = rendererParams.params.directLight;

auto &world = frameData.world;

// Compute ambient light contribution //
const float aoFactor = directLightParams.aoSamples > 0
? computeAO(ss,
ray,
hit,
rendererParams.occlusionDistance,
directLightParams.aoSamples,
&surfaceAttenuation)
: 1.f;

vec3 contrib = materialEvaluateEmission(shadingState, -ray.dir);

// Handle ambient light contribution
if (rendererParams.ambientIntensity > 0.0f) {
contrib += rendererParams.ambientColor * rendererParams.ambientIntensity
* materialEvaluateTint(shadingState);
}

for (size_t l = 0; l < inst->numLights; l++) {
// Handle all lights contributions
for (size_t i = 0; i < world.numLightInstances; i++) {
const auto &light = world.lightInstances[i];
const auto lightSample =
sampleLight(ss, hit, inst->indices[l], inst->xfm);
sampleLight(ss, hit, light.lightIndex, light.xfm);

if (lightSample.pdf == 0.0f)
continue;

Expand All @@ -114,50 +112,49 @@ struct DirectLightShadingPolicy

contrib += thisLightContrib * attenuation;
}
}

// Take AO in account
contrib *= aoFactor;

// Then proceed with single bounce ray for indirect lighting
SurfaceHit bounceHit = hit;
NextRay nextRay = materialNextRay(shadingState, ray, ss.rs);
if (glm::any(glm::greaterThan(
nextRay.contributionWeight, glm::vec3(MIN_CONTRIBUTION_EPSILON)))) {
Ray bounceRay = {
bounceHit.hitpoint
+ bounceHit.Ng
* std::copysignf(
bounceHit.epsilon, dot(bounceHit.Ns, nextRay.direction)),
nextRay.direction,
};

// Only check for intersecting surfaces and background as secondary light
// interactions
bounceHit.foundHit = false;
intersectSurface(ss, bounceRay, RayType::PRIMARY, &bounceHit);

if (bounceHit.foundHit) {
// We hit something. Gather its contribution, cosine weighted diffuse
// only, we want this to be lightweight.
MaterialShadingState bounceShadingState;
materialInitShading(
&bounceShadingState, frameData, *bounceHit.material, bounceHit);

auto sampleDir = randomDir(ss.rs, bounceHit.Ns);
auto cosineT = dot(bounceHit.Ns, sampleDir);
auto color = materialEvaluateTint(bounceShadingState) * cosineT;
contrib += color * nextRay.contributionWeight;
} else {
// No hit, get background contribution directly (no surface to weight
// against)
const auto color = getBackground(frameData, ss.screen, bounceRay.dir);
contrib += vec3(color) * nextRay.contributionWeight;
// Take AO in account
contrib *= aoFactor;

// Then proceed with single bounce ray for indirect lighting
SurfaceHit bounceHit = hit;
NextRay nextRay = materialNextRay(shadingState, ray, ss.rs);
if (glm::any(glm::greaterThan(
nextRay.contributionWeight, glm::vec3(MIN_CONTRIBUTION_EPSILON)))) {
Ray bounceRay = {
bounceHit.hitpoint
+ bounceHit.Ng
* std::copysignf(
bounceHit.epsilon, dot(bounceHit.Ns, nextRay.direction)),
normalize(nextRay.direction),
};

// Only check for intersecting surfaces and background as secondary light
// interactions
bounceHit.foundHit = false;
intersectSurface(ss, bounceRay, RayType::PRIMARY, &bounceHit);

if (bounceHit.foundHit) {
// We hit something. Gather its contribution, cosine weighted diffuse
// only, we want this to be lightweight.
MaterialShadingState bounceShadingState;
materialInitShading(
&bounceShadingState, frameData, *bounceHit.material, bounceHit);

auto sampleDir = randomDir(ss.rs, bounceHit.Ns);
auto cosineT = dot(bounceHit.Ns, sampleDir);
auto color = materialEvaluateTint(bounceShadingState) * cosineT;
contrib += color * nextRay.contributionWeight;
} else {
// No hit, get background contribution directly (no surface to weight
// against)
const auto color = getBackground(frameData, ss.screen, bounceRay.dir);
contrib += vec3(color) * nextRay.contributionWeight;
}
}
}

float opacity = evaluateOpacity(shadingState);
return vec4(contrib, opacity);
float opacity = evaluateOpacity(shadingState);
return vec4(contrib, opacity);
}
};

Expand Down
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