From 15740faf9fe9fe4be08965098bbf2947e096aeeb Mon Sep 17 00:00:00 2001
From: chai <chaifix@163.com>
Date: Wed, 14 Aug 2019 22:50:43 +0800
Subject: +Unity Runtime code

---
 Runtime/Camera/LODGroupManager.cpp | 462 +++++++++++++++++++++++++++++++++++++
 1 file changed, 462 insertions(+)
 create mode 100644 Runtime/Camera/LODGroupManager.cpp

(limited to 'Runtime/Camera/LODGroupManager.cpp')

diff --git a/Runtime/Camera/LODGroupManager.cpp b/Runtime/Camera/LODGroupManager.cpp
new file mode 100644
index 0000000..0463cf3
--- /dev/null
+++ b/Runtime/Camera/LODGroupManager.cpp
@@ -0,0 +1,462 @@
+#include "UnityPrefix.h"
+#include "LODGroupManager.h"
+#include "LODGroup.h"
+#include "CullingParameters.h"
+#include "Runtime/Profiler/Profiler.h"
+#include "Runtime/Utilities/BitUtility.h"
+#include "Runtime/Camera/RenderLoops/BuiltinShaderParamUtility.h"
+#include "Runtime/Misc/BuildSettings.h"
+
+PROFILER_INFORMATION (gComputeLOD, "LOD.ComputeLOD", kProfilerRender)
+
+LODGroupManager* gLODGroupManager = NULL;
+
+LODGroupManager& GetLODGroupManager ()
+{
+	Assert(gLODGroupManager != NULL);
+	return *gLODGroupManager;
+}
+
+LODGroupManager* GetLODGroupManagerPtr ()
+{
+	return gLODGroupManager;
+}
+void CleanupLODGroupManager ()
+{
+	Assert(gLODGroupManager != NULL);
+	UNITY_DELETE (gLODGroupManager, kMemRenderer);
+}
+
+void InitializeLODGroupManager ()
+{
+	Assert(gLODGroupManager == NULL);
+	gLODGroupManager = UNITY_NEW_AS_ROOT(LODGroupManager(), kMemRenderer, "LODGroupManager", "");
+}
+
+
+LODGroupManager::LODGroupManager ()
+{
+	m_LODBias = 1.0F;
+	m_MaximumLOD = 0;
+	
+	memset(&m_SelectionData.push_back(), 0, sizeof(LODSelectionData));
+}
+
+// The basic LOD distance check in orthomode:
+// * Pixel size check: if (array[i].pixelHeight < lodGroup.m_Size * 0.5F / parameters.orthoSize * parameters.cameraPixelHeight)
+// * Relative height check: if (array[i].relativeHeight < lodGroup.m_Size * 0.5F / parameters.orthoSize)
+
+// The basic LOD distance check in perspective:
+// ...
+
+// All LOD calculations are distance based "reference point in LOD group" to camera position.
+// - Rotating a camera never switches LOD
+// - Point based means it's very predictable behaviour that is easy to visualize accurately
+// - Fast to calculate
+//  float distance = CalculateFOVDistanceFudge () * CaclulateLODDistance();
+
+
+float CalculateFOVHalfAngle (const CullingParameters& parameters)
+{
+	return tan(Deg2Rad (parameters.lodFieldOfView) * 0.5F);
+}
+
+enum { kScreenRelativeMetric = 0, kPixelMetric = 1, kMetricCount = 2 };
+
+void CalculateLODFudge (const CullingParameters& parameters, float* fudge)
+{
+	float screenRelativeMetric;
+	if (parameters.isOrthographic)
+	{
+		screenRelativeMetric = 2.0F * parameters.orthoSize;
+	}
+	else
+	{
+		// Half angle at 90 degrees is 1.0 (So we skip halfAngle / 1.0 calculation)
+		float halfAngle = CalculateFOVHalfAngle(parameters);
+		screenRelativeMetric = 2.0 * halfAngle;
+	}
+
+	fudge[kScreenRelativeMetric] = screenRelativeMetric;
+	fudge[kPixelMetric] = screenRelativeMetric / parameters.cameraPixelHeight;
+}
+
+float CalculateLODDistance (float relativeScreenHeight, float size)
+{
+	return size / relativeScreenHeight;
+}
+
+float DistanceToRelativeHeight (const CullingParameters& parameters, float distance, float size)
+{
+	if (parameters.isOrthographic)
+	{
+		return size * 0.5F / parameters.orthoSize;
+	}
+	else
+	{
+		float halfAngle = CalculateFOVHalfAngle(parameters);
+		return size * 0.5F / (distance * halfAngle);
+	}
+}
+
+
+void LODGroupManager::CalculatePerspectiveLODMask (const LODSelectionData& selection, const Vector3f& position, int maximumLOD, int currentMask, const float* fieldOfViewFudge, UInt8* output, float* fade)
+{
+	if (selection.forceLODLevelMask != 0)
+	{
+		*output = selection.forceLODLevelMask;
+		*fade = 1.0F;
+		return;
+	}
+	
+	Vector3f offset = selection.worldReferencePoint - position;
+	
+	float sqrDistance = SqrMagnitude(offset);
+	sqrDistance *= fieldOfViewFudge[kScreenRelativeMetric] * fieldOfViewFudge[kScreenRelativeMetric];
+	
+	// Early out if the object is getting culled because it is too far away.
+	*output = 0;
+	*fade = 0.0F;
+	
+	// Must use the same metric for everything.... Otherwise this will fail
+	if (sqrDistance > selection.maxDistanceSqr)
+		return;
+	
+	int maxDistancesCount = selection.maxDistancesCount;
+	const float* distances = selection.maxDistances;
+	
+	bool supportsFade = selection.fadeDistance != 0.0F;
+	
+	for (int i=maximumLOD;i<maxDistancesCount;i++)
+	{
+		// Is camera closer than maximum LOD distance?
+		float lodMaxDistance = distances[i];
+		float lodMaxDistanceSqr = lodMaxDistance * lodMaxDistance;
+		
+		if (sqrDistance < lodMaxDistanceSqr)
+		{
+			// @TODO: This if could be optimized out of the inner loop
+			if (supportsFade)
+			{
+				// Is the next LOD in the transition range?
+				float dif = lodMaxDistance - sqrt(sqrDistance);
+				if (dif < selection.fadeDistance)
+				{
+					currentMask |= currentMask << 1;
+					*output = currentMask;
+					*fade = dif / selection.fadeDistance;
+				}
+				else
+				{
+					///@TODO: this should be zero, because when you are not fading it shouldn't use a shader that does fading.
+					*output = currentMask;
+					*fade = 1.0F;
+				}
+			}
+			else
+			{
+				///@TODO: this should be zero, because when you are not fading it shouldn't use a shader that does fading.
+				*output = currentMask;
+				*fade = 1.0F;
+			}
+			
+			return;
+		}
+		
+		currentMask <<= 1;
+	}
+}
+
+void LODGroupManager::CalculateOrthoLODMask (const LODSelectionData& selection, int maximumLOD, int currentMask, const float* fudge, UInt8* output, float* fade)
+{
+	if (selection.forceLODLevelMask != 0)
+	{
+		*output = selection.forceLODLevelMask;
+		*fade = 1.0F;
+		return;
+	}
+	
+	///@TODO: DO IT
+	*output = 0;
+	*fade = 0.0F;
+	
+	int maxDistancesCount = selection.maxDistancesCount;
+	const float* distances = selection.maxDistances;
+
+	float distance = fudge[kScreenRelativeMetric];
+
+	for (int i=maximumLOD;i<maxDistancesCount;i++)
+	{
+		if (distance < distances[i])
+		{
+			// Is the next LOD in the transition range?
+			float dif = distances[i] - distance;
+			if (dif < selection.fadeDistance)
+			{
+				currentMask |= currentMask << 1;
+				*output = currentMask;
+				*fade = dif / selection.fadeDistance;
+			}
+			else
+			{
+				///@TODO: this should be zero, because when you are not fading it shouldn't use a shader that does fading.
+				*output = currentMask;
+				*fade = 1.0F;
+			}
+			
+			return;
+		}
+		
+		currentMask <<= 1;
+	}
+}
+
+void LODGroupManager::CalculateLODMasks (const CullingParameters& parameters, UInt8* outMasks, float* outFades)
+{
+	PROFILER_AUTO(gComputeLOD, NULL)
+
+	// Get field of view / pixel fudge values and sqr it so the inner loop doesn't have to do it.
+	float fieldOfViewFudge[kMetricCount];
+	CalculateLODFudge (parameters, fieldOfViewFudge);
+	for (int i=0;i<kMetricCount;i++)
+		fieldOfViewFudge[i] = fieldOfViewFudge[i] / m_LODBias;
+
+	int lodGroupCount = m_SelectionData.size();
+	DebugAssert(lodGroupCount > 0);
+	outMasks[0] = 0;
+	outFades[0] = 0;
+	int baseMask = 1 << m_MaximumLOD;
+	if (parameters.isOrthographic)
+	{
+		for (int i=1;i<lodGroupCount;i++)
+			CalculateOrthoLODMask(m_SelectionData[i], m_MaximumLOD, baseMask, fieldOfViewFudge, &outMasks[i], &outFades[i]);
+	}
+	else
+	{
+		for (int i=1;i<lodGroupCount;i++)
+			CalculatePerspectiveLODMask(m_SelectionData[i], parameters.lodPosition, m_MaximumLOD, baseMask, fieldOfViewFudge, &outMasks[i], &outFades[i]);
+	}
+}
+
+inline UInt32 LowestBit2Consecutive8Bit (UInt32 v)
+{
+	Assert(v == (v & 0xff));
+	UInt32 extra = (v & (v - 1)) == 0;
+	v |= v >> 1;
+	v |= v >> 2;
+	v |= v >> 4;
+	v++;
+	
+	UInt32 table[] = { v >> 2, v >> 1 };
+	return table[extra];
+}
+
+// The shader isn't using clamp on the z value of the 3D dither texture.
+// Thus we have to ensure that it never actually becomes 1.0
+inline float ClampForGPURepeat (float fade)
+{
+	return clamp(fade, 0.0F, LOD_FADE_DISABLED);
+}
+
+float LODGroupManager::CalculateLODFade (UInt32 lodGroupIndex, UInt32 rendererActiveLODMask, const UInt8* lodMasks, const float* lodFades)
+{
+	if (rendererActiveLODMask == 0)
+		return LOD_FADE_DISABLED;
+	
+	// rendererActiveLODMask:
+	// The mask of all LOD levels that this renderer participates in.
+	
+	// The mask of all active LOD levels for this group.
+	// Eg. LOD 0 and LOD1 enabled -> 1 | 2
+	UInt8 activeMaskOfLODGroup = lodMasks[lodGroupIndex];
+	
+	// If renderer is part of all active LOD groups, then it should be completely visible.
+	if ((rendererActiveLODMask & activeMaskOfLODGroup) == activeMaskOfLODGroup)
+		return LOD_FADE_DISABLED;
+	
+	// If the renderer is part of the lowest bit then it is part of the highest LOD (duh!)
+	bool isPartOfHighLOD = LowestBit2Consecutive8Bit (activeMaskOfLODGroup) & rendererActiveLODMask;
+	
+	// The highest LOD Level uses the computed fade value
+	if (isPartOfHighLOD)
+	{
+		return ClampForGPURepeat(lodFades[lodGroupIndex]);
+	}
+	// The lower lod level uses the inverse
+	else
+	{
+		return ClampForGPURepeat(1.0F - lodFades[lodGroupIndex]);
+	}
+}
+
+void LODGroupManager::ClearAllForceLODMask ()
+{
+	for (int i=0;i<m_SelectionData.size();i++)
+		m_SelectionData[i].forceLODLevelMask = 0;
+
+}
+
+#if UNITY_EDITOR
+static void AddRenderersToVisualizationStats (const LODGroup::LODRenderers& renderers, LODVisualizationInformation& information)
+{
+	// Calculate triangle & vertex & mesh count for the renderers in this LOD
+	for (int i=0;i<renderers.size();i++)
+	{
+		Renderer* renderer = renderers[i].renderer;
+		if (renderer)
+		{
+			RenderStats stats;
+			renderer->GetRenderStats (stats);
+			
+			information.triangleCount += stats.triangleCount;
+			information.vertexCount   += stats.vertexCount;
+			information.rendererCount += 1;
+			information.submeshCount  += stats.submeshCount;
+		}
+	}
+}
+
+LODVisualizationInformation LODGroupManager::CalculateVisualizationData (const CullingParameters& cullingParameters, LODGroup& lodGroup, int lodLevel)
+{
+	LODVisualizationInformation information;
+	memset(&information, 0, sizeof(information));
+	information.activeLODLevel = kInvalidLODGroup;
+	
+	// Calculate switch distance
+	float fudge[kMetricCount];
+	CalculateLODFudge (cullingParameters, fudge);
+	for (int i=0;i<kMetricCount;i++)
+		fudge[i] = fudge[i] / m_LODBias;
+	
+	float sqrFudge[kMetricCount];
+	for (int i=0;i<kMetricCount;i++)
+		sqrFudge[i] = fudge[i];
+	float lodFade = 0.0F;
+
+	if (lodGroup.m_LODGroup != kInvalidLODGroup && lodGroup.m_LODGroup != kDisabledLODGroup)
+	{
+		UInt8 activeLODMask;
+		if (cullingParameters.isOrthographic)
+			CalculateOrthoLODMask (m_SelectionData[lodGroup.m_LODGroup], m_MaximumLOD, 1 << m_MaximumLOD, sqrFudge, &activeLODMask, &lodFade);
+		else
+			CalculatePerspectiveLODMask (m_SelectionData[lodGroup.m_LODGroup], cullingParameters.lodPosition, m_MaximumLOD, 1 << m_MaximumLOD, sqrFudge, &activeLODMask, &lodFade);
+		
+		if (activeLODMask != 0)
+			information.activeLODLevel = LowestBit(activeLODMask);
+		else
+			information.activeLODLevel = -1;
+	}
+	
+	if (lodLevel == -1)
+		lodLevel = information.activeLODLevel;
+
+	// Calculate current distances & bounding volume sizes
+	information.activeDistance = Magnitude(lodGroup.GetWorldReferencePoint() - cullingParameters.lodPosition);
+	information.activeRelativeScreenSize = DistanceToRelativeHeight(cullingParameters, information.activeDistance, lodGroup.GetWorldSpaceSize()) * m_LODBias;
+	information.activePixelSize = information.activeRelativeScreenSize * cullingParameters.cameraPixelHeight;
+	information.activeWorldSpaceSize = lodGroup.GetWorldSpaceSize ();
+	information.activeLODFade = lodFade;
+	
+	if (lodLevel != -1)
+	{
+		// Calculate switch distance for the lod
+		const LODGroup::LOD& lod = lodGroup.m_LODs[lodLevel];
+		
+		// Calculate triangle & vertex & mesh count for the renderers in this LOD
+		AddRenderersToVisualizationStats(lod.renderers, information);
+	}
+	
+	return information;
+}
+#endif //UNITY_EDITOR
+
+void LODGroupManager::AddLODGroup (LODGroup& group, const Vector3f& position, float worldSpaceSize)
+{
+	// Add Group
+	int index = m_SelectionData.size();
+	m_SelectionData.push_back();
+	group.m_LODGroup = index;
+
+	// Initialize parameters
+	UpdateLODGroupParameters(index, group, position, worldSpaceSize);
+	
+	m_SelectionData.back().forceLODLevelMask = 0;
+}
+
+void  LODGroupManager::UpdateLODGroupParameters (int index, LODGroup& group, const Vector3f& position, float worldSpaceSize)
+{
+	LODSelectionData& data = m_SelectionData[index];
+
+	data.worldReferencePoint = position;
+	data.lodGroup = &group;
+	data.maxDistancesCount = group.m_LODs.size();
+	data.maxDistanceSqr = 0.0F;
+	
+	Assert(group.m_LODs.size() <= kMaximumLODLevels);
+	
+	float totalMaxDistance = 0.0F;
+	
+	if (!GetBuildSettings ().hasAdvancedVersion)
+	{
+		data.maxDistancesCount = std::max (1, data.maxDistancesCount);
+		totalMaxDistance = data.maxDistances[0] = CalculateLODDistance(0.0001F, worldSpaceSize);
+	}
+	else
+	{
+		
+		for (int i=0;i<group.m_LODs.size();i++)
+		{
+			float maxDistance =	CalculateLODDistance(group.m_LODs[i].screenRelativeHeight, worldSpaceSize);
+		
+			totalMaxDistance = std::max(maxDistance, totalMaxDistance);
+			data.maxDistances[i] = maxDistance;
+		}
+	}
+
+	data.maxDistanceSqr = totalMaxDistance * totalMaxDistance;
+	
+	bool useLODFade = group.m_ScreenRelativeTransitionHeight > 0.00001F && !group.m_LODs.empty();
+	if (useLODFade)
+	{
+		float baseRelativeHeight = group.m_LODs.front().screenRelativeHeight;
+		data.fadeDistance = CalculateLODDistance (baseRelativeHeight - group.m_ScreenRelativeTransitionHeight, worldSpaceSize) - CalculateLODDistance (baseRelativeHeight, worldSpaceSize);
+	}
+	else
+		data.fadeDistance = 0.0F;
+}
+
+void LODGroupManager::RemoveLODGroup (LODGroup& group)
+{
+	// Remove from array by replacing with the last element.
+	Assert(group.m_CachedRenderers.empty());
+	
+	int index = group.m_LODGroup;
+	Assert(index != 0);
+	
+	// Update LODGroup index of the LODGroup we moved from the back
+	m_SelectionData.back().lodGroup->NotifyLODGroupManagerIndexChange(index);
+
+	m_SelectionData[index] = m_SelectionData.back();
+	m_SelectionData.pop_back();
+	
+	group.m_LODGroup = kInvalidLODGroup;
+}
+
+
+#if ENABLE_UNIT_TESTS
+
+#include "External/UnitTest++/src/UnitTest++.h"
+
+SUITE (LODGroupManagerTests)
+{
+TEST (LODGroupManagerTests_PrevPowerOfTwoUInt8)
+{
+	for (int i=0;i<7;i++)
+	{
+		CHECK_EQUAL (1 << i, LowestBit2Consecutive8Bit(1 << i));
+		CHECK_EQUAL (1 << i, LowestBit2Consecutive8Bit((1 << i) | (1 << (i+1))));
+	}
+}
+}
+
+#endif
-- 
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