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path tracer cubemap render #277

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4114baf
handles projection matrix of cubemap renders, raygen for cubemap render
keptsecret May 6, 2026
080de3a
fix writing to rwmc cascade array layer, draw cubemap as unfolded t v…
keptsecret May 6, 2026
bd6242a
Merge branch 'master' into pt_cubemap_render
keptsecret May 7, 2026
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4 changes: 2 additions & 2 deletions 40_PathTracer/app_resources/pathtrace/beauty.hlsl
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ struct CCascades
inline uint16_t3 __getCoord(const uint16_t cascadeIx)
{
uint16_t3 coord = _static_cast<uint16_t3>(spirv::LaunchIdKHR);
coord.z = coord.z*uint16_t(6)+cascadeIx;
coord.z = coord.z+cascadeIx*uint16_t(spirv::LaunchSizeKHR.z);
return coord;
}

Expand Down Expand Up @@ -249,7 +249,7 @@ void raygen()
// fetch random variable from memory
const float32_t3 randVec = randgen(0u,sampleIndex);
// TODO: motion blur and lens DOF triplet

// get our NDC coordinates and ray
const float32_t2 pixelSizeNDC = promote<float32_t2>(2.f)/float32_t2(spirv::LaunchSizeKHR.xy);
const float32_t2 NDC = float32_t2(launchID.xy)*pixelSizeNDC - promote<float32_t2>(1.f);
Expand Down
38 changes: 34 additions & 4 deletions 40_PathTracer/app_resources/pathtrace/common.hlsl
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Expand Up @@ -285,13 +285,43 @@ SPrimaryRay genPrimaryRay(const SSensorDynamics sensor, const float32_t2 pixelSi
retval.ray.origin = hlsl::transpose(sensor.invView)[3];
float32_t3 viewDir;
if (spirv::LaunchSizeKHR.z != 6u)
{
viewDir = float32_t3(hlsl::mul(sensor.ndcToRay, adjNDC), -1.0);
viewDir = hlsl::normalize(viewDir);
retval.tMin = sensor.nearClip / hlsl::abs(viewDir.z);
}
else
{
// TODO: handle cubemap cameras
// TODO: handle cubemap cameras
const uint16_t faceID = spirv::LaunchIdKHR.z;
const float32_t2 coord = adjNDC.xy;
switch(faceID)
{
case 0: // +X
viewDir = float32_t3(1.0, -coord.y, -coord.x);
break;
case 1: // -X
viewDir = float32_t3(-1.0, -coord.y, coord.x);
break;
case 2: // +Y
viewDir = float32_t3(coord.x, 1.0, coord.y);
break;
case 3: // -Y
viewDir = float32_t3(coord.x, -1.0, -coord.y);
break;
case 4: // +Z
viewDir = float32_t3(coord.x, -coord.y, 1.0);
break;
case 5: // -Z
viewDir = float32_t3(-coord.x, -coord.y, -1.0);
break;
default:
viewDir = float32_t3(0,0,0);
}
viewDir = hlsl::normalize(viewDir);
const float32_t maxComponent = hlsl::max(hlsl::abs(viewDir.x), hlsl::max(hlsl::abs(viewDir.y), hlsl::abs(viewDir.z)));
retval.tMin = sensor.nearClip / maxComponent;
}
viewDir = hlsl::normalize(viewDir);
retval.tMin = sensor.nearClip / hlsl::abs(viewDir.z);
retval.ray.direction.setDirection(viewDir);
}
// rotate and scale with camera
Expand Down Expand Up @@ -410,7 +440,7 @@ struct SArbitraryOutputValues
// To follow through 2 or more reflections we'd need to multiply these 3x3 matrices together along the ray like so
// `(I - 2 n_0 n_0^T) (I - 2 n_1 n_1^T) = I + 4 n_0 (n_0^T n_1) n_1^T - 2 (n_0 n_0^T + n_1 n_1^T)`
// Theoretically because every series of reflections is just one reflection and a rotation, it could be possible to store this in 3 floats, due to the properties of SO(3)
// "The orthogonal group, consisting of all proper and improper rotations, is generated by reflections. Every proper rotation is the composition of two reflections, a special case of the Cartan�Dieudonn� theorem."
// "The orthogonal group, consisting of all proper and improper rotations, is generated by reflections. Every proper rotation is the composition of two reflections, a special case of the Cartan�Dieudonn� theorem."
// I'm not sure how we could extend that for refractions but probably a similar form is possible - virtual object corresponding under transmission to what's seen under refraction.
// The question is.. is it worth it? Do er really need objects warped by in a labyrynth of wonky mirrors to have warped normals? Or a ceiling reflected in a choppy swimming pool to inherit the pool's wave normals ?
// NO because this is an input to a denoiser to stop it blurring lighting across surfaces oriented in different directions! Doesn't matter what the reflection and refraction normals are as long as they're consistent.
Expand Down
48 changes: 43 additions & 5 deletions 40_PathTracer/app_resources/present/default.hlsl
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Expand Up @@ -22,11 +22,49 @@ float32_t4 present_default(SVertexAttributes vxAttr) : SV_Target0
float32_t3 uv;
if (pc.isCubemap)
{
const float32_t4 ndc = float32_t4(vxAttr.uv*2.f-float32_t2(1,1),1.f,1.f);
float32_t4 tmp = mul(pc.cubemap().invProjView,ndc);
float32_t3 dir = tmp.xyz/tmp.www;
// TODO: convert dir to cubemap face, and the UV coord
tint = float32_t3(1,0,1); // right now go magenta error colour
// TODO: currently unused
// const float32_t4 ndc = float32_t4(vxAttr.uv*2.f-float32_t2(1,1),1.f,1.f);
// float32_t4 tmp = mul(pc.cubemap().invProjView,ndc);
// float32_t3 dir = tmp.xyz/tmp.www;

const uint32_t x = uint32_t(floor(vxAttr.uv.x * 4.0));
const uint32_t y = uint32_t(floor(vxAttr.uv.y * 3.0));
const float32_t one_third = 1.0/3.0;
if (y == 1)
{
float32_t2 coord = float32_t2(vxAttr.uv.x * 4.0, (vxAttr.uv.y - one_third) * 3.0);
uv.xy = float32_t2(coord.x - float32_t(x) * 1.0, coord.y);
switch (x) // tile index
{
case 0: // -X
uv.z = 1.f;
break;
case 1: // +Z
uv.z = 4.f;
break;
case 2: // +X
uv.z = 0.f;
break;
case 3: // -Z
uv.z = 5.f;
break;
}
}
else if (x == 1)
{
uv.xy = float32_t2((vxAttr.uv.x - 0.25) * 4.0, (vxAttr.uv.y - float32_t(y) * one_third) * 3.0);
switch (y)
{
case 0: // +Y
uv.z = 2.f;
break;
case 2: // -Y
uv.z = 3.f;
break;
}
}
else
return float32_t4(0,0,0,1);
}
else
{
Expand Down
10 changes: 8 additions & 2 deletions 40_PathTracer/src/renderer/present/CWindowPresenter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@
#include "renderer/present/CWindowPresenter.h"
#include "renderer/shaders/session.hlsl"

#include "nbl/builtin/hlsl/math/thin_lens_projection.hlsl"

namespace nbl::this_example
{
using namespace nbl::core;
Expand Down Expand Up @@ -193,8 +195,12 @@ auto CWindowPresenter::acquire_impl(const CSession* session, ISemaphore::SWaitIn
uint16_t2 targetResolution = m_pushConstants.isCubemap ? maxResolution:sessionParams.uniforms.renderSize;
if (m_pushConstants.isCubemap)
{
// TODO: build default perspective projection matrix given aspect ratio and smaller axis (or diagonal) FOV of the viewer
// m_pushConstants.cubemap.invProjView = ;
const auto invView = math::linalg::promote_affine<4,4>(sessionParams.initDynamics.invView);
// TODO: consider handedness, right now right hand
const auto originalAspectRatio = float32_t(targetResolution.x) / float32_t(targetResolution.y);
const auto proj = buildProjectionMatrixPerspectiveFovRH(numbers::pi<float32_t> * 0.5f, originalAspectRatio, sessionParams.initDynamics.nearClip, sessionParams.initDynamics.tMax);
const auto invProj = hlsl::inverse(proj);
m_pushConstants.cubemap.invProjView = hlsl::mul(invView, invProj);
}
else
{
Expand Down