Hlsl path tracer #224

devshgraphicsprogramming · 2025-11-03T16:17:03Z

@keptsecret after you merge master again, you'll probably have the UI mess up and show changed from the merge commit, so close and reopen again

TODO

4 unresolved conversations from RWMC #218, check if done

devshgraphicsprogramming · 2025-12-15T21:06:43Z

31_HLSLPathTracer/app_resources/hlsl/rwmc_global_settings_common.hlsl

+#ifndef _NBL_HLSL_PATHTRACER_RWMC_GLOBAL_SETTINGS_COMMON_INCLUDED_
+#define _NBL_HLSL_PATHTRACER_RWMC_GLOBAL_SETTINGS_COMMON_INCLUDED_
+#include "nbl/builtin/hlsl/cpp_compat.hlsl"
+
+NBL_CONSTEXPR uint32_t CascadeCount = 6u;
+
+#endif


kinda silly having one header just for this

kick it into the main common file

devshgraphicsprogramming · 2025-12-15T21:08:07Z

31_HLSLPathTracer/app_resources/hlsl/scene.hlsl

+    Shape<scalar_type, PST_SPHERE> light_spheres[1];
+    Shape<scalar_type, PST_TRIANGLE> light_triangles[1];
+    Shape<scalar_type, PST_RECTANGLE> light_rectangles[1];


you shouldn't need unused members if you have getters

devshgraphicsprogramming · 2025-12-15T21:08:55Z

31_HLSLPathTracer/include/nbl/this_example/transform.hpp

+		if (ImGui::IsKeyPressed(ImGuiKey_S) && params.allowedOp & ImGuizmo::OPERATION::SCALE) // for triangle/rectangle
+			mCurrentGizmoOperation = ImGuizmo::SCALE_X | ImGuizmo::SCALE_Y;
+
+#if 0


whats this if 0 about?

devshgraphicsprogramming · 2025-12-15T21:19:32Z

31_HLSLPathTracer/app_resources/hlsl/render_common.hlsl

+#ifndef __HLSL_VERSION
+#include "matrix4SIMD.h"
+#endif


remove the include, not needed

devshgraphicsprogramming · 2025-12-15T21:21:54Z

31_HLSLPathTracer/app_resources/hlsl/render_rwmc_common.hlsl

+struct RenderRWMCPushConstants
+{
+	RenderPushConstants renderPushConstants;
+	nbl::hlsl::rwmc::SplattingParameters splattingParameters;


the splatting params shoul have never been compressed in Nabla, they should have been compressed here, and a getter/setter method here too

devshgraphicsprogramming · 2025-12-15T21:22:46Z

31_HLSLPathTracer/app_resources/hlsl/resolve.comp.hlsl

+#ifdef PERSISTENT_WORKGROUPS
+#include "nbl/builtin/hlsl/math/morton.hlsl"
+#endif


devshgraphicsprogramming · 2025-12-15T21:23:26Z

31_HLSLPathTracer/app_resources/hlsl/resolve.comp.hlsl

+
+    float32_t3 color = resolve(accessor, int16_t2(coords.x, coords.y));
+
+    //float32_t3 color = rwmc::reweight<rwmc::ResolveAccessorAdaptor<float> >(pc.resolveParameters, cascade, coords);


remove commented code

devshgraphicsprogramming · 2025-12-15T21:23:49Z

31_HLSLPathTracer/app_resources/hlsl/resolve_common.hlsl

+#ifndef _NBL_HLSL_PATHTRACER_RESOLVE_COMMON_INCLUDED_
+#define _NBL_HLSL_PATHTRACER_RESOLVE_COMMON_INCLUDED_


wrong header guard, this is userspace code

devshgraphicsprogramming · 2025-12-15T21:24:25Z

31_HLSLPathTracer/app_resources/hlsl/resolve_common.hlsl

+
+struct ResolvePushConstants
+{
+	uint32_t sampleCount;


unused variable

devshgraphicsprogramming · 2025-12-15T21:28:21Z

31_HLSLPathTracer/main.cpp

+		RenderRWMCPushConstants rwmcPushConstants;
+		RenderPushConstants pc;
+		ResolvePushConstants resolvePushConstants;


don't you rebuild them every frame from imgui stuff + camera etc?

Maybe lets not store them around as global state and have them transient

devshgraphicsprogramming · 2025-12-15T21:29:54Z

31_HLSLPathTracer/main.cpp

+		std::array<smart_refctd_ptr<IGPUComputePipeline>, E_LIGHT_GEOMETRY::ELG_COUNT> m_PTGLSLPipelines;
+		std::array<smart_refctd_ptr<IGPUComputePipeline>, E_LIGHT_GEOMETRY::ELG_COUNT> m_PTHLSLPipelines;
+		std::array<smart_refctd_ptr<IGPUComputePipeline>, E_LIGHT_GEOMETRY::ELG_COUNT> m_PTGLSLPersistentWGPipelines;
+		std::array<smart_refctd_ptr<IGPUComputePipeline>, E_LIGHT_GEOMETRY::ELG_COUNT> m_PTHLSLPersistentWGPipelines;
+		std::array<smart_refctd_ptr<IGPUComputePipeline>, E_LIGHT_GEOMETRY::ELG_COUNT> m_PTHLSLPipelinesRWMC;
+		std::array<smart_refctd_ptr<IGPUComputePipeline>, E_LIGHT_GEOMETRY::ELG_COUNT> m_PTHLSLPersistentWGPipelinesRWMC;


you can delete GLSL code now

devshgraphicsprogramming · 2025-12-15T21:30:34Z

31_HLSLPathTracer/main.cpp

+		void updatePathtracerPushConstants()
+		{
+			// disregard surface/swapchain transformation for now
+			const auto viewProjectionMatrix = m_camera.getConcatenatedMatrix();
+			// TODO: rewrite the `Camera` class so it uses hlsl::float32_t4x4 instead of core::matrix4SIMD
+			core::matrix4SIMD invMVP;
+			viewProjectionMatrix.getInverseTransform(invMVP);
+			if (useRWMC)
+			{
+				memcpy(&rwmcPushConstants.renderPushConstants.invMVP, invMVP.pointer(), sizeof(rwmcPushConstants.renderPushConstants.invMVP));
+				rwmcPushConstants.renderPushConstants.generalPurposeLightMatrix = hlsl::float32_t3x4(transpose(m_lightModelMatrix));
+				rwmcPushConstants.renderPushConstants.depth = depth;
+				rwmcPushConstants.renderPushConstants.sampleCount = resolvePushConstants.sampleCount = spp;
+				rwmcPushConstants.renderPushConstants.pSampleSequence = m_sequenceBuffer->getDeviceAddress();
+				//rwmcPushConstants.splattingParameters.log2Start = std::log2(rwmcStart);
+				//rwmcPushConstants.splattingParameters.log2Base = std::log2(rwmcBase);
+				float32_t2 packLogs = float32_t2(std::log2(rwmcStart), std::log2(rwmcBase));
+				rwmcPushConstants.splattingParameters.packedLog2 = hlsl::packHalf2x16(packLogs);
+			}
+			else
+			{
+				memcpy(&pc.invMVP, invMVP.pointer(), sizeof(pc.invMVP));
+				pc.generalPurposeLightMatrix = hlsl::float32_t3x4(transpose(m_lightModelMatrix));
+				pc.sampleCount = spp;
+				pc.depth = depth;
+				pc.pSampleSequence = m_sequenceBuffer->getDeviceAddress();
+			}
+		}


you can move into a lambda somwhere in workLoopBody

devshgraphicsprogramming · 2025-12-15T21:31:04Z

31_HLSLPathTracer/main.cpp

+		float rwmcMinReliableLuma;
+		float rwmcKappa;
+		float rwmcStart;
+		float rwmcBase;


gather them up, make nicer create methods for splatting and resolve params

see #218 (comment)

devshgraphicsprogramming · 2025-12-16T14:33:51Z

31_HLSLPathTracer/app_resources/hlsl/render.comp.hlsl

+    const float32_t2 unpacked = hlsl::unpackHalf2x16(pc.packedSplattingParams);
+    rwmc::SplattingParameters splattingParameters = rwmc::SplattingParameters::create(unpacked[0], unpacked[1]);
+    accumulator_type accumulator = accumulator_type::create(splattingParameters);


add a get and set method to RenderRWMCPushConstants

devshgraphicsprogramming · 2025-12-17T17:27:11Z

31_HLSLPathTracer/app_resources/hlsl/resolve.comp.hlsl

    float32_t3 color = resolve(accessor, int16_t2(coords.x, coords.y));

-    //float32_t3 color = rwmc::reweight<rwmc::ResolveAccessorAdaptor<float> >(pc.resolveParameters, cascade, coords);
+    //float32_t3 color = rwmc::reweight<ResolveAccessorAdaptor<float> >(pc.resolveParameters, cascade, coords);


whats this commented out code, if not used then remove it

devshgraphicsprogramming · 2025-12-17T17:27:41Z

31_HLSLPathTracer/main.cpp

+				float32_t2 packParams = float32_t2(rwmcBase, rwmcStart);
+				rwmcPushConstants.packedSplattingParams = hlsl::packHalf2x16(packParams);


we need a setter method for the packed params

devshgraphicsprogramming · 2025-12-19T20:27:01Z

31_HLSLPathTracer/app_resources/hlsl/pathtracer.hlsl

+#ifndef _NBL_HLSL_PATHTRACING_INCLUDED_
+#define _NBL_HLSL_PATHTRACING_INCLUDED_
+
+#include <nbl/builtin/hlsl/colorspace/EOTF.hlsl>
+#include <nbl/builtin/hlsl/colorspace/encodeCIEXYZ.hlsl>
+#include <nbl/builtin/hlsl/math/functions.hlsl>
+#include <nbl/builtin/hlsl/sampling/basic.hlsl>
+#include <nbl/builtin/hlsl/bxdf/bxdf_traits.hlsl>
+#include <nbl/builtin/hlsl/sampling/quantized_sequence.hlsl>
+#include <nbl/builtin/hlsl/vector_utils/vector_traits.hlsl>
+#include "concepts.hlsl"
+
+namespace nbl
+{
+namespace hlsl
+{
+namespace path_tracing
+{
+
+template<class RandGen, class RayGen, class Intersector, class MaterialSystem, /* class PathGuider, */ class NextEventEstimator, class Accumulator, class Scene
+NBL_PRIMARY_REQUIRES(concepts::RandGenerator<RandGen> && concepts::RayGenerator<RayGen> &&
+    concepts::Intersector<Intersector> && concepts::MaterialSystem<MaterialSystem> &&
+    concepts::NextEventEstimator<NextEventEstimator> && concepts::Accumulator<Accumulator> &&
+    concepts::Scene<Scene>)
+struct Unidirectional
+{
+    using this_t = Unidirectional<RandGen, RayGen, Intersector, MaterialSystem, NextEventEstimator, Accumulator, Scene>;


all this needs to go to Nabla repo

devshgraphicsprogramming · 2025-12-19T20:30:15Z

31_HLSLPathTracer/app_resources/hlsl/rand_gen.hlsl

+template<typename RNG>
+struct Uniform1D
+{
+    using rng_type = RNG;
+    using return_type = uint32_t;
+
+    static Uniform1D<RNG> construct(uint32_t2 seed)
+    {
+        Uniform1D<RNG> retval;
+        retval.rng = rng_type::construct(seed);
+        return retval;
+    }
+
+    return_type operator()()
+    {
+        return rng();
+    }
+
+    rng_type rng;
+};
+
+template<typename RNG>
+struct Uniform3D
+{
+    using rng_type = RNG;
+    using return_type = uint32_t3;
+
+    static Uniform3D<RNG> construct(uint32_t2 seed)
+    {
+        Uniform3D<RNG> retval;
+        retval.rng = rng_type::construct(seed);
+        return retval;
+    }
+
+    return_type operator()()
+    {
+        return return_type(rng(), rng(), rng());
+    }
+
+    rng_type rng;
+};


these need also static return_type __call(NBL_REF_ARG(rng_type) rng)

AND to be in Nabla repo

devshgraphicsprogramming · 2025-12-19T20:30:53Z

31_HLSLPathTracer/app_resources/hlsl/ray_gen.hlsl

+    static this_t create(NBL_CONST_REF_ARG(vector2_type) pixOffsetParam, NBL_CONST_REF_ARG(vector3_type) camPos, NBL_CONST_REF_ARG(vector4_type) NDC, NBL_CONST_REF_ARG(matrix4x4_type) invMVP)
+    {
+        this_t retval;
+        retval.pixOffsetParam = pixOffsetParam;
+        retval.camPos = camPos;
+        retval.NDC = NDC;
+        retval.invMVP = invMVP;
+        return retval;
+    }


again, lets not make useless psedo-constructors

devshgraphicsprogramming · 2025-12-19T20:32:05Z

31_HLSLPathTracer/app_resources/hlsl/ray_gen.hlsl

+        // #if POLYGON_METHOD==2
+        //     ray._immutable.normalAtOrigin = vec3(0.0,0.0,0.0);
+        //     ray._immutable.wasBSDFAtOrigin = false;
+        // #endif
+
+        ray.payload.accumulation = (vector3_type)0.0;
+        ray.payload.otherTechniqueHeuristic = 0.0; // needed for direct eye-light paths
+        ray.payload.throughput = (vector3_type)1.0;
+        // #ifdef KILL_DIFFUSE_SPECULAR_PATHS
+        // ray._payload.hasDiffuse = false;
+        // #endif


payload shouldn't be initialized by raygen, just the direction

devshgraphicsprogramming · 2025-12-19T20:32:51Z

31_HLSLPathTracer/app_resources/hlsl/ray_gen.hlsl

+        // apply stochastic reconstruction filter
+        const float gaussianFilterCutoff = 2.5;
+        const float truncation = nbl::hlsl::exp(-0.5 * gaussianFilterCutoff * gaussianFilterCutoff);
+        vector2_type remappedRand = randVec.xy;
+        remappedRand.x *= 1.0 - truncation;
+        remappedRand.x += truncation;
+        nbl::hlsl::sampling::BoxMullerTransform<scalar_type> boxMuller;
+        boxMuller.stddev = 1.5;
+        tmp.xy += pixOffsetParam * boxMuller(remappedRand);


wrap this up in another struct, this is a Stochastic Reconstruction Filter of which one can have Tent, Box, etc. this one is Gaussian

devshgraphicsprogramming · 2025-12-19T20:33:37Z

31_HLSLPathTracer/app_resources/hlsl/ray_gen.hlsl

+#ifndef _NBL_HLSL_EXT_RAYGEN_INCLUDED_
+#define _NBL_HLSL_EXT_RAYGEN_INCLUDED_
+
+#include <nbl/builtin/hlsl/sampling/box_muller_transform.hlsl>
+
+#include "common.hlsl"
+
+namespace RayGen
+{
+
+template<class Ray>
+struct Basic
+{
+    using this_t = Basic<Ray>;
+    using ray_type = Ray;
+    using scalar_type = typename Ray::scalar_type;
+    using vector3_type = typename Ray::vector3_type;
+


this looks useful put it in the path_tracing namespace and builtin directory as DefaultRayGen or BasicRayGen

keptsecret added 30 commits February 3, 2025 14:52

copied ex 30 to new ex 31

eab0f70

ignore events on imgui focus

8521123

initial files for pathtracer

b171724

intersection logic

af35393

changes to intersection logic

5a5fbfe

completed material system?

85e67ad

sphere nee stuff

2c500b1

triangle sampling

e6a9916

rectangle sampling

6dc25eb

nee stuff

22bd6f9

scene representation, getmeasure for pt

3bb858b

moved scene rep out, some closest hit stuff

f5adbf6

sample light part of closest hit

159d153

fix bugs, reorganize traceRay

a7350db

sample bsdf in closest hit

8a4e0a9

set up path tracer render shader

72104b8

finish render shader

202c645

hlsl path tracer initial, bug fixes

2f77555

fix shader bugs

99aed47

Merge branch 'master' into hlsl_path_tracer

a1a8ec0

bug fixes #3

a802a97

fix include when embed resources off

eed47e7

fixed more bugs #4

6e26dae

Merge branch 'master' into hlsl_path_tracer

3827fd3

fix compile hlsl shader bug

da661c0

more bug fixes #5

f97757b

more bug fixes #6

8e759f2

Merge branch 'master' into hlsl_path_tracer

2dfadfe

refactor to use new frisvad

b1831d9

fix bugs again

cb5662a

devshgraphicsprogramming commented Dec 15, 2025

View reviewed changes

devshgraphicsprogramming mentioned this pull request Dec 15, 2025

RWMC #218

Merged

keptsecret added 6 commits December 16, 2025 10:58

Merge branch 'master' into hlsl_path_tracer

cb14ea4

refactor partitionRandVar changes

6956bf1

refactor rwmc splatting params usage

5b5df48

remove assigning texture inside struct

cf20436

moved accessor impl into user space

facdf42

refactor splatting params usage again

fd034ec

devshgraphicsprogramming commented Dec 16, 2025

View reviewed changes

fix luma coefficient

caa80c2

devshgraphicsprogramming commented Dec 17, 2025

View reviewed changes

devshgraphicsprogramming commented Dec 19, 2025

View reviewed changes


		float32_t3 color = resolve(accessor, int16_t2(coords.x, coords.y));

		//float32_t3 color = rwmc::reweight<rwmc::ResolveAccessorAdaptor<float> >(pc.resolveParameters, cascade, coords);

		#ifndef _NBL_HLSL_PATHTRACER_RESOLVE_COMMON_INCLUDED_
		#define _NBL_HLSL_PATHTRACER_RESOLVE_COMMON_INCLUDED_

		float32_t2 packParams = float32_t2(rwmcBase, rwmcStart);
		rwmcPushConstants.packedSplattingParams = hlsl::packHalf2x16(packParams);

Hlsl path tracer #224

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Hlsl path tracer #224

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devshgraphicsprogramming commented Nov 3, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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TODO

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devshgraphicsprogramming commented Nov 3, 2025 •

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devshgraphicsprogramming Dec 15, 2025 •

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