From bf90df100e120e272c14c7975a22ed01bf3ad215 Mon Sep 17 00:00:00 2001
From: Lizzy Fleckenstein <eliasfleckenstein@web.de>
Date: Thu, 13 Apr 2023 08:40:18 +0200
Subject: Add back lighting system

Code is taken from latest irrlicht trunk; this is relevant because there have been fixes to stencil shadows since 1.8.5 (irrlicht SVN revision 5933).
---
 source/Irrlicht/CShadowVolumeSceneNode.cpp | 531 +++++++++++++++++++++++++++++
 1 file changed, 531 insertions(+)
 create mode 100644 source/Irrlicht/CShadowVolumeSceneNode.cpp

(limited to 'source/Irrlicht/CShadowVolumeSceneNode.cpp')

diff --git a/source/Irrlicht/CShadowVolumeSceneNode.cpp b/source/Irrlicht/CShadowVolumeSceneNode.cpp
new file mode 100644
index 0000000..da38c22
--- /dev/null
+++ b/source/Irrlicht/CShadowVolumeSceneNode.cpp
@@ -0,0 +1,531 @@
+// Copyright (C) 2002-2012 Nikolaus Gebhardt
+// This file is part of the "Irrlicht Engine".
+// For conditions of distribution and use, see copyright notice in irrlicht.h
+
+#include "IrrCompileConfig.h"
+
+#ifdef _IRR_COMPILE_WITH_SHADOW_VOLUME_SCENENODE_
+
+#include "CShadowVolumeSceneNode.h"
+#include "ISceneManager.h"
+#include "IMesh.h"
+#include "IVideoDriver.h"
+#include "ICameraSceneNode.h"
+#include "SViewFrustum.h"
+#include "SLight.h"
+#include "os.h"
+
+namespace irr
+{
+namespace scene
+{
+
+
+//! constructor
+CShadowVolumeSceneNode::CShadowVolumeSceneNode(const IMesh* shadowMesh, ISceneNode* parent,
+		ISceneManager* mgr, s32 id, bool zfailmethod, f32 infinity)
+: IShadowVolumeSceneNode(parent, mgr, id),
+	AdjacencyDirtyFlag(true),
+	ShadowMesh(0), IndexCount(0), VertexCount(0), ShadowVolumesUsed(0),
+	Infinity(infinity), UseZFailMethod(zfailmethod), Optimization(ESV_SILHOUETTE_BY_POS)
+{
+	#ifdef _DEBUG
+	setDebugName("CShadowVolumeSceneNode");
+	#endif
+	setShadowMesh(shadowMesh);
+	setAutomaticCulling(scene::EAC_OFF);
+}
+
+
+//! destructor
+CShadowVolumeSceneNode::~CShadowVolumeSceneNode()
+{
+	if (ShadowMesh)
+		ShadowMesh->drop();
+}
+
+
+void CShadowVolumeSceneNode::createShadowVolume(const core::vector3df& light, bool isDirectional)
+{
+	SShadowVolume* svp = 0;
+	core::aabbox3d<f32>* bb = 0;
+
+	// builds the shadow volume and adds it to the shadow volume list.
+
+	if (ShadowVolumes.size() > ShadowVolumesUsed)
+	{
+		// get the next unused buffer
+
+		svp = &ShadowVolumes[ShadowVolumesUsed];
+		svp->set_used(0);
+
+		bb = &ShadowBBox[ShadowVolumesUsed];
+	}
+	else
+	{
+		ShadowVolumes.push_back(SShadowVolume());
+		svp = &ShadowVolumes.getLast();
+
+		ShadowBBox.push_back(core::aabbox3d<f32>());
+		bb = &ShadowBBox.getLast();
+	}
+	svp->reallocate(IndexCount*5);
+	++ShadowVolumesUsed;
+
+	// We use triangle lists
+	Edges.set_used(IndexCount*2);
+	u32 numEdges = 0;
+
+	numEdges=createEdgesAndCaps(light, isDirectional, svp, bb);
+
+	// for all edges add the near->far quads
+	core::vector3df lightDir1(light*Infinity);
+	core::vector3df lightDir2(light*Infinity);
+	for (u32 i=0; i<numEdges; ++i)
+	{
+		const core::vector3df &v1 = Vertices[Edges[2*i+0]];
+		const core::vector3df &v2 = Vertices[Edges[2*i+1]];
+		if ( !isDirectional )
+		{
+			lightDir1 = (v1 - light).normalize()*Infinity;
+			lightDir2 = (v2 - light).normalize()*Infinity;
+		}
+		const core::vector3df v3(v1+lightDir1);
+		const core::vector3df v4(v2+lightDir2);
+
+		// Add a quad (two triangles) to the vertex list
+#ifdef _DEBUG
+		if (svp->size() >= svp->allocated_size()-5)
+			os::Printer::log("Allocation too small.", ELL_DEBUG);
+#endif
+		svp->push_back(v1);
+		svp->push_back(v2);
+		svp->push_back(v3);
+
+		svp->push_back(v2);
+		svp->push_back(v4);
+		svp->push_back(v3);
+	}
+}
+
+// TODO.
+// Not sure what's going on. Either FaceData should mean the opposite and true should mean facing away from light
+// or I'm missing something else. Anyway - when not setting this then Shadows will look wrong on Burnings driver
+// while they seem to look OK on first view either way on other drivers. Only tested with z-fail so far.
+// Maybe errors only show up close to near/far plane on other drivers as otherwise the stencil-buffer-count 
+// is probably ending up with same value anyway 
+#define IRR_USE_REVERSE_EXTRUDED
+
+u32 CShadowVolumeSceneNode::createEdgesAndCaps(const core::vector3df& light, bool isDirectional,
+					SShadowVolume* svp, core::aabbox3d<f32>* bb)
+{
+	u32 numEdges=0;
+	const u32 faceCount = IndexCount / 3;
+
+	if(faceCount >= 1)
+		bb->reset(Vertices[Indices[0]]);
+	else
+		bb->reset(0,0,0);
+
+	// Check every face if it is front or back facing the light.
+	core::vector3df lightDir0(light);
+	core::vector3df lightDir1(light);
+	core::vector3df lightDir2(light);
+	for (u32 i=0; i<faceCount; ++i)
+	{
+		const core::vector3df v0 = Vertices[Indices[3*i+0]];
+		const core::vector3df v1 = Vertices[Indices[3*i+1]];
+		const core::vector3df v2 = Vertices[Indices[3*i+2]];
+
+		if ( !isDirectional )
+		{
+			lightDir0 = (v0-light).normalize();
+		}
+#ifdef IRR_USE_REVERSE_EXTRUDED
+		FaceData[i]=core::triangle3df(v2,v1,v0).isFrontFacing(lightDir0);	// actually the back-facing polygons
+#else
+		FaceData[i]=core::triangle3df(v0,v1,v2).isFrontFacing(lightDir0);
+#endif
+
+#if 0	// Useful for internal debugging & testing. Show all the faces in the light.
+		if ( FaceData[i] )
+		{
+			video::SMaterial m;
+			m.Lighting = false;
+			SceneManager->getVideoDriver()->setMaterial(m);
+#ifdef IRR_USE_REVERSE_EXTRUDED
+			SceneManager->getVideoDriver()->draw3DTriangle(core::triangle3df(v0+lightDir0,v1+lightDir0,v2+lightDir0), irr::video::SColor(255,255, 0, 0));
+#else
+			SceneManager->getVideoDriver()->draw3DTriangle(core::triangle3df(v0-lightDir0,v1-lightDir0,v2-lightDir0), irr::video::SColor(255,255, 0, 0));
+#endif
+		}
+#endif
+
+		if (UseZFailMethod && FaceData[i])
+		{
+#ifdef _DEBUG
+			if (svp->size() >= svp->allocated_size()-5)
+				os::Printer::log("Allocation too small.", ELL_DEBUG);
+#endif
+			// add front cap from light-facing faces
+			svp->push_back(v2);
+			svp->push_back(v1);
+			svp->push_back(v0);
+
+			// add back cap
+			if ( !isDirectional )
+			{
+				lightDir1 = (v1-light).normalize();
+				lightDir2 = (v2-light).normalize();
+			}
+			const core::vector3df i0 = v0+lightDir0*Infinity;
+			const core::vector3df i1 = v1+lightDir1*Infinity;
+			const core::vector3df i2 = v2+lightDir2*Infinity;
+
+			svp->push_back(i0);
+			svp->push_back(i1);
+			svp->push_back(i2);
+
+			bb->addInternalPoint(i0);
+			bb->addInternalPoint(i1);
+			bb->addInternalPoint(i2);
+		}
+	}
+
+	// Create edges
+	for (u32 i=0; i<faceCount; ++i)
+	{
+		// check all front facing faces
+		if (FaceData[i] == true)
+		{
+			const u16 wFace0 = Indices[3*i+0];
+			const u16 wFace1 = Indices[3*i+1];
+			const u16 wFace2 = Indices[3*i+2];
+
+			if ( Optimization == ESV_NONE )
+			{
+				// add edge v0-v1
+				Edges[2*numEdges+0] = wFace0;
+				Edges[2*numEdges+1] = wFace1;
+				++numEdges;
+
+				// add edge v1-v2
+				Edges[2*numEdges+0] = wFace1;
+				Edges[2*numEdges+1] = wFace2;
+				++numEdges;
+
+				// add edge v2-v0
+				Edges[2*numEdges+0] = wFace2;
+				Edges[2*numEdges+1] = wFace0;
+				++numEdges;
+			}
+			else
+			{
+				const u16 adj0 = Adjacency[3*i+0];
+				const u16 adj1 = Adjacency[3*i+1];
+				const u16 adj2 = Adjacency[3*i+2];
+
+				// add edges if face is adjacent to back-facing face
+				// or if no adjacent face was found
+				if (adj0 == i || FaceData[adj0] == false)
+				{
+					// add edge v0-v1
+					Edges[2*numEdges+0] = wFace0;
+					Edges[2*numEdges+1] = wFace1;
+					++numEdges;
+				}
+
+				if (adj1 == i || FaceData[adj1] == false)
+				{
+					// add edge v1-v2
+					Edges[2*numEdges+0] = wFace1;
+					Edges[2*numEdges+1] = wFace2;
+					++numEdges;
+				}
+
+				if (adj2 == i || FaceData[adj2] == false)
+				{
+					// add edge v2-v0
+					Edges[2*numEdges+0] = wFace2;
+					Edges[2*numEdges+1] = wFace0;
+					++numEdges;
+				}
+			}
+		}
+	}
+	return numEdges;
+}
+
+
+void CShadowVolumeSceneNode::setShadowMesh(const IMesh* mesh)
+{
+	if (ShadowMesh == mesh)
+		return;
+	if (ShadowMesh)
+		ShadowMesh->drop();
+	ShadowMesh = mesh;
+	if (ShadowMesh)
+	{
+		ShadowMesh->grab();
+		Box = ShadowMesh->getBoundingBox();
+	}
+}
+
+
+void CShadowVolumeSceneNode::updateShadowVolumes()
+{
+	const u32 oldIndexCount = IndexCount;
+	const u32 oldVertexCount = VertexCount;
+
+	VertexCount = 0;
+	IndexCount = 0;
+	ShadowVolumesUsed = 0;
+
+	const IMesh* const mesh = ShadowMesh;
+	if (!mesh)
+		return;
+
+	// create as much shadow volumes as there are lights but
+	// do not ignore the max light settings.
+	const u32 lightCount = SceneManager->getVideoDriver()->getDynamicLightCount();
+	if (!lightCount)
+		return;
+
+	// calculate total amount of vertices and indices
+
+	u32 i;
+	u32 totalVertices = 0;
+	u32 totalIndices = 0;
+	const u32 bufcnt = mesh->getMeshBufferCount();
+
+	for (i=0; i<bufcnt; ++i)
+	{
+		const IMeshBuffer* buf = mesh->getMeshBuffer(i);
+		if (	buf->getIndexType() == video::EIT_16BIT 
+			&& buf->getPrimitiveType() == scene::EPT_TRIANGLES )
+		{
+			totalIndices += buf->getIndexCount();
+			totalVertices += buf->getVertexCount();
+		}
+		else
+		{
+			os::Printer::log("ShadowVolumeSceneNode only supports meshbuffers with 16 bit indices and triangles", ELL_WARNING);
+			return;
+		}
+	}
+	if ( totalIndices != (u32)(u16)totalIndices)
+	{
+		// We could switch to 32-bit indices, not much work and just bit of extra memory (< 192k) per shadow volume.
+		// If anyone ever complains and really needs that just switch it. But huge shadows are usually a bad idea as they will be slow.
+		os::Printer::log("ShadowVolumeSceneNode does not yet support shadowvolumes which need more than 16 bit indices", ELL_WARNING);
+		return;
+	}
+
+	// allocate memory if necessary
+
+	Vertices.set_used(totalVertices);
+	Indices.set_used(totalIndices);
+	FaceData.resize(totalIndices / 3);
+
+	// copy mesh 
+	// (could speed this up for static meshes by adding some user flag to prevents copying)
+	for (i=0; i<bufcnt; ++i)
+	{
+		const IMeshBuffer* buf = mesh->getMeshBuffer(i);
+
+		const u16* idxp = buf->getIndices();
+		const u16* idxpend = idxp + buf->getIndexCount();
+		for (; idxp!=idxpend; ++idxp)
+			Indices[IndexCount++] = *idxp + VertexCount;
+
+		const u32 vtxcnt = buf->getVertexCount();
+		for (u32 j=0; j<vtxcnt; ++j)
+			Vertices[VertexCount++] = buf->getPosition(j);
+	}
+
+	// recalculate adjacency if necessary
+	if (oldVertexCount != VertexCount || oldIndexCount != IndexCount || AdjacencyDirtyFlag)
+		calculateAdjacency();
+
+	core::matrix4 matInv(Parent->getAbsoluteTransformation());
+	matInv.makeInverse();
+	core::matrix4 matTransp(Parent->getAbsoluteTransformation(), core::matrix4::EM4CONST_TRANSPOSED);
+	const core::vector3df parentpos = Parent->getAbsolutePosition();
+
+	for (i=0; i<lightCount; ++i)
+	{
+		const video::SLight& dl = SceneManager->getVideoDriver()->getDynamicLight(i);
+
+		if ( dl.Type == video::ELT_DIRECTIONAL )
+		{
+			core::vector3df ldir(dl.Direction);
+			matTransp.transformVect(ldir);
+			createShadowVolume(ldir, true);
+		}
+		else
+		{
+			core::vector3df lpos(dl.Position);
+			if (dl.CastShadows &&
+				fabs((lpos - parentpos).getLengthSQ()) <= (dl.Radius*dl.Radius*4.0f))
+			{
+				matInv.transformVect(lpos);
+				createShadowVolume(lpos, false);
+			}
+		}
+	}
+}
+
+void CShadowVolumeSceneNode::setOptimization(ESHADOWVOLUME_OPTIMIZATION optimization)
+{
+	if ( Optimization != optimization )
+	{
+		Optimization = optimization;
+		AdjacencyDirtyFlag = true;
+	}
+}
+
+//! pre render method
+void CShadowVolumeSceneNode::OnRegisterSceneNode()
+{
+	if (IsVisible)
+	{
+		SceneManager->registerNodeForRendering(this, scene::ESNRP_SHADOW);
+		ISceneNode::OnRegisterSceneNode();
+	}
+}
+
+//! renders the node.
+void CShadowVolumeSceneNode::render()
+{
+	video::IVideoDriver* driver = SceneManager->getVideoDriver();
+
+	if (!ShadowVolumesUsed || !driver)
+		return;
+
+	driver->setTransform(video::ETS_WORLD, Parent->getAbsoluteTransformation());
+
+	bool checkFarPlaneClipping = UseZFailMethod && !driver->queryFeature(video::EVDF_DEPTH_CLAMP);
+
+	// get camera frustum converted to local coordinates when we have to check for far plane clipping
+	SViewFrustum frust;
+	if ( checkFarPlaneClipping )
+	{
+		const irr::scene::ICameraSceneNode* camera = SceneManager->getActiveCamera();
+		if ( camera )
+		{
+			frust = *camera->getViewFrustum();
+			core::matrix4 invTrans(Parent->getAbsoluteTransformation(), core::matrix4::EM4CONST_INVERSE);
+			frust.transform(invTrans);
+		}
+		else
+			checkFarPlaneClipping = false;
+	}
+
+	for (u32 i=0; i<ShadowVolumesUsed; ++i)
+	{
+		bool drawShadow = true;
+
+		if (checkFarPlaneClipping)
+		{
+			// Disable shadows drawing, when back cap is behind of ZFar plane.
+			// TODO: Using infinite projection matrices instead is said to work better
+			//       as then we wouldn't fail when the shadow clip the far plane.
+			//       I couldn't get it working (and neither anyone before me it seems).
+			//       Anyone who can figure it out is welcome to provide a patch.
+
+			core::vector3df edges[8];
+			ShadowBBox[i].getEdges(edges);
+
+			for(int j = 0; j < 8; ++j)
+			{
+				if (frust.planes[scene::SViewFrustum::VF_FAR_PLANE].classifyPointRelation(edges[j]) == core::ISREL3D_FRONT)
+				{
+					drawShadow = false;
+					break;
+				}
+			}
+		}
+
+		if(drawShadow)
+			driver->drawStencilShadowVolume(ShadowVolumes[i], UseZFailMethod, DebugDataVisible);
+		else
+		{
+			// TODO: For some reason (not yet further investigated), Direct3D needs a call to drawStencilShadowVolume
+			//       even if we have nothing to draw here to set the renderstate into a StencilShadowMode.
+			//       If that's not done it has effect on further render calls.
+			core::array<core::vector3df> triangles;
+			driver->drawStencilShadowVolume(triangles, UseZFailMethod, DebugDataVisible);
+		}
+	}
+}
+
+
+//! returns the axis aligned bounding box of this node
+const core::aabbox3d<f32>& CShadowVolumeSceneNode::getBoundingBox() const
+{
+	return Box;
+}
+
+
+//! Generates adjacency information based on mesh indices.
+void CShadowVolumeSceneNode::calculateAdjacency()
+{
+	AdjacencyDirtyFlag = false;
+
+	if ( Optimization == ESV_NONE )
+	{
+		Adjacency.clear();
+	}
+	else if ( Optimization == ESV_SILHOUETTE_BY_POS )
+	{
+		Adjacency.set_used(IndexCount);
+
+		// go through all faces and fetch their three neighbours
+		for (u32 f=0; f<IndexCount; f+=3)
+		{
+			for (u32 edge = 0; edge<3; ++edge)
+			{
+				const core::vector3df& v1 = Vertices[Indices[f+edge]];
+				const core::vector3df& v2 = Vertices[Indices[f+((edge+1)%3)]];
+
+				// now we search an_O_ther _F_ace with these two
+				// vertices, which is not the current face.
+				u32 of;
+
+				for (of=0; of<IndexCount; of+=3)
+				{
+					// only other faces
+					if (of != f)
+					{
+						bool cnt1 = false;
+						bool cnt2 = false;
+
+						for (s32 e=0; e<3; ++e)
+						{
+							if (v1.equals(Vertices[Indices[of+e]]))
+								cnt1=true;
+
+							if (v2.equals(Vertices[Indices[of+e]]))
+								cnt2=true;
+						}
+						// one match for each vertex, i.e. edge is the same
+						if (cnt1 && cnt2)
+							break;
+					}
+				}
+
+				// no adjacent edges -> store face number, else store adjacent face
+				if (of >= IndexCount)
+					Adjacency[f + edge] = f/3;
+				else
+					Adjacency[f + edge] = of/3;
+			}
+		}
+	}
+}
+
+
+} // end namespace scene
+} // end namespace irr
+
+#endif // _IRR_COMPILE_WITH_SHADOW_VOLUME_SCENENODE_
-- 
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