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USD Viewer: added option to use orthographic camera
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@TheMostDiligent
TheMostDiligent committed Jan 8, 2025
1 parent 02db4a5 commit c81406e
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Showing 2 changed files with 52 additions and 20 deletions.
67 changes: 48 additions & 19 deletions Samples/USDViewer/src/USDViewer.cpp
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright 2023-2024 Diligent Graphics LLC
* Copyright 2023-2025 Diligent Graphics LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
Expand Down Expand Up @@ -845,14 +845,24 @@ void USDViewer::UpdateUI()
const auto CameraDist = m_Camera.GetDist();
const pxr::GfVec2f ClippingRange{CameraDist / 100.f, CameraDist * 3.f};

ImGui::SliderFloat("Focal Length (mm)", &m_CameraSettings.FocalLength_mm, 24.0, 300.0);
ImGui::SliderFloat("Aperture (f-stop)", &m_CameraSettings.FStop, 1.0, 64.0, "%.3f", ImGuiSliderFlags_Logarithmic);
ImGui::SliderFloat("Exposure", &m_CameraSettings.Exposure, -8.0, +8.0, "%.3f");
ImGui::SliderFloat("Focus Distance", &m_CameraSettings.FocusDistance, ClippingRange[0], ClippingRange[1], "%.3f", ImGuiSliderFlags_AlwaysClamp);
ImGui::SliderFloat("Sensor Width", &m_CameraSettings.SensorWidth_mm, 1, 100);
ImGui::Combo("Projection", &m_CameraSettings.Projection,
"Perspective\0"
"Orthographic\0");

{
ImGui::ScopedDisabler Disabler{m_CameraSettings.Projection != 0, 0.5f};
ImGui::SliderFloat("Focal Length (mm)", &m_CameraSettings.FocalLength_mm, 24.0, 300.0);
ImGui::SliderFloat("Aperture (f-stop)", &m_CameraSettings.FStop, 1.0, 64.0, "%.3f", ImGuiSliderFlags_Logarithmic);
ImGui::SliderFloat("Focus Distance", &m_CameraSettings.FocusDistance, ClippingRange[0], ClippingRange[1], "%.3f", ImGuiSliderFlags_AlwaysClamp);
ImGui::SliderFloat("Sensor Width", &m_CameraSettings.SensorWidth_mm, 1, 100);
}

{
ImGui::ScopedDisabler Disabler{true, 0.5f};
ImGui::SliderFloat("Sensor Height", &m_CameraSettings.SensorHeight_mm, 1, 100);
}

ImGui::ScopedDisabler Disabler{true, 0.5f};
ImGui::SliderFloat("Sensor Height", &m_CameraSettings.SensorHeight_mm, 1, 100);
ImGui::SliderFloat("Exposure", &m_CameraSettings.Exposure, -8.0, +8.0, "%.3f");

ImGui::TreePop();
}
Expand Down Expand Up @@ -1253,20 +1263,40 @@ void USDViewer::UpdateCamera()
const float4x4 USDCameraView = m_CameraView * float4x4::Scale(UnitsPerMeter, UnitsPerMeter, -UnitsPerMeter);

const SwapChainDesc& SCDesc = m_pSwapChain->GetDesc();
m_CameraSettings.SensorHeight_mm = m_CameraSettings.SensorWidth_mm / static_cast<float>(SCDesc.Width) * static_cast<float>(SCDesc.Height);
const float AspectRatio = static_cast<float>(SCDesc.Height) / static_cast<float>(SCDesc.Width);
m_CameraSettings.SensorHeight_mm = m_CameraSettings.SensorWidth_mm * AspectRatio;
const float FOV = 2.0f * atanf(m_CameraSettings.SensorHeight_mm / (2.0 * m_CameraSettings.FocalLength_mm));
const pxr::GfVec2f ClippingRange{CameraDist / 100.f, CameraDist * 3.f};
// Get projection matrix adjusted to the current screen orientation
m_CameraProj = GetAdjustedProjectionMatrix(FOV, ClippingRange[0], ClippingRange[1]);
const pxr::GfVec2f ClippingRangeMeters{CameraDist / 100.f, CameraDist * 3.f};

m_CameraSettings.FocusDistance = clamp(m_CameraSettings.FocusDistance, ClippingRange[0] + m_CameraSettings.FocalLength_mm * 0.001f, ClippingRange[1]);
const float MillimetersPerUnit = m_Stage.MetersPerUnit * 1000.f;

float HorzApertureUnits = 0;
float VertApertureUnits = 0;
if (m_CameraSettings.Projection == 0)
{
HorzApertureUnits = m_CameraSettings.SensorWidth_mm / MillimetersPerUnit;
VertApertureUnits = m_CameraSettings.SensorHeight_mm / MillimetersPerUnit;

m_CameraProj = GetAdjustedProjectionMatrix(FOV, ClippingRangeMeters[0], ClippingRangeMeters[1]);
m_Stage.Camera.GetProjectionAttr().Set(pxr::UsdGeomTokens->perspective);
}
else
{
HorzApertureUnits = 0.0625 * ClippingRangeMeters[1] / m_Stage.MetersPerUnit;
VertApertureUnits = HorzApertureUnits * AspectRatio;

m_CameraProj = float4x4::Ortho(HorzApertureUnits * m_Stage.MetersPerUnit, VertApertureUnits * m_Stage.MetersPerUnit, ClippingRangeMeters[0], ClippingRangeMeters[1], false);
m_Stage.Camera.GetProjectionAttr().Set(pxr::UsdGeomTokens->orthographic);
}

m_CameraSettings.FocusDistance = clamp(m_CameraSettings.FocusDistance, ClippingRangeMeters[0] + m_CameraSettings.FocalLength_mm * 0.001f, ClippingRangeMeters[1]);

m_Stage.Camera.MakeMatrixXform().Set(USD::ToGfMatrix4d((m_Stage.RootTransform * USDCameraView).Inverse()));
m_Stage.Camera.GetFStopAttr().Set(m_CameraSettings.FStop);
m_Stage.Camera.GetExposureAttr().Set(m_CameraSettings.Exposure);

// USD camera properties are measured in scene units
m_Stage.Camera.GetClippingRangeAttr().Set(ClippingRange / m_Stage.MetersPerUnit);
m_Stage.Camera.GetClippingRangeAttr().Set(ClippingRangeMeters / m_Stage.MetersPerUnit);
m_Stage.Camera.GetFocusDistanceAttr().Set(m_CameraSettings.FocusDistance / m_Stage.MetersPerUnit);

// By an odd convention, lens and filmback properties are measured in tenths of a scene unit rather than "raw" scene units.
Expand All @@ -1277,13 +1307,12 @@ void USDViewer::UpdateCamera()
// float focalLength;
// UsdCamera.GetFocalLengthAttr().Get(&focalLength); // focalLength == 30
// However
// focalLength = SceneDelegate->GetCameraParamValue(id, HdCameraTokens->focalLength).Get<float>(); // focalLength == 3

// focalLength = SceneDelegate->GetCameraParamValue(id, HdCameraTokens->focalLength).Get<float>(); // focalLength ==
constexpr float UsdCamLensUnitScale = 10;
const float MillimetersPerUnit = m_Stage.MetersPerUnit * 1000.f;

m_Stage.Camera.GetFocalLengthAttr().Set(m_CameraSettings.FocalLength_mm * UsdCamLensUnitScale / MillimetersPerUnit);
m_Stage.Camera.GetHorizontalApertureAttr().Set(m_CameraSettings.SensorWidth_mm * UsdCamLensUnitScale / MillimetersPerUnit);
m_Stage.Camera.GetVerticalApertureAttr().Set(m_CameraSettings.SensorHeight_mm * UsdCamLensUnitScale / MillimetersPerUnit);
m_Stage.Camera.GetHorizontalApertureAttr().Set(HorzApertureUnits * UsdCamLensUnitScale);
m_Stage.Camera.GetVerticalApertureAttr().Set(VertApertureUnits * UsdCamLensUnitScale);
}

void USDViewer::Update(double CurrTime, double ElapsedTime)
Expand Down
5 changes: 4 additions & 1 deletion Samples/USDViewer/src/USDViewer.hpp
View file
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright 2023-2024 Diligent Graphics LLC
* Copyright 2023-2025 Diligent Graphics LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
Expand Down Expand Up @@ -179,6 +179,9 @@ class USDViewer final : public SampleBase
// Sensor width and height in millimeters
float SensorWidth_mm = 36.0f;
float SensorHeight_mm = 24.0f;

// 0 - perspective, 1 - orthographic
int Projection = 0;
} m_CameraSettings;

struct RenderStats
Expand Down

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