Fix handling of skinned meshes for nodes

- Rigidly animated models (e.g. the gltf frog node) were not working correctly,
  since cloning the mesh ignored the transformation matrices.
  Note that scaling the mesh needs to occur *after* transforming the vertices.
- Visual scale did not apply to skinned models,
  as resetting the animation overwrote scaled vertex data with static positions & normals.
  For backwards compatibility, we only apply a 10x scale to static (.obj) models.

src/client/content_mapblock.cpp

@@ -1676,7 +1676,7 @@ void MapblockMeshGenerator::drawMeshNode()
 
 	if (cur_node.f->mesh_ptr) {
 		// clone and rotate mesh
-		mesh = cloneMesh(cur_node.f->mesh_ptr);
+		mesh = cloneStaticMesh(cur_node.f->mesh_ptr);
 		bool modified = true;
 		if (facedir)
 			rotateMeshBy6dFacedir(mesh, facedir);

src/client/mesh.cpp

@@ -3,6 +3,8 @@
 // Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
 
 #include "mesh.h"
+#include "IMeshBuffer.h"
+#include "SSkinMeshBuffer.h"
 #include "debug.h"
 #include "log.h"
 #include <cmath>
@@ -102,6 +104,21 @@ scene::IAnimatedMesh* createCubeMesh(v3f scale)
 	return anim_mesh;
 }
 
+template<typename F>
+inline static void transformMeshBuffer(scene::IMeshBuffer *buf,
+		const F &transform_vertex)
+{
+	const u32 stride = getVertexPitchFromType(buf->getVertexType());
+	u32 vertex_count = buf->getVertexCount();
+	u8 *vertices = (u8 *)buf->getVertices();
+	for (u32 i = 0; i < vertex_count; i++) {
+		auto *vertex = (video::S3DVertex *)(vertices + i * stride);
+		transform_vertex(vertex);
+	}
+	buf->setDirty(scene::EBT_VERTEX);
+	buf->recalculateBoundingBox();
+}
+
 void scaleMesh(scene::IMesh *mesh, v3f scale)
 {
 	if (mesh == NULL)
@@ -112,14 +129,9 @@ void scaleMesh(scene::IMesh *mesh, v3f scale)
 	u32 mc = mesh->getMeshBufferCount();
 	for (u32 j = 0; j < mc; j++) {
 		scene::IMeshBuffer *buf = mesh->getMeshBuffer(j);
-		const u32 stride = getVertexPitchFromType(buf->getVertexType());
-		u32 vertex_count = buf->getVertexCount();
-		u8 *vertices = (u8 *)buf->getVertices();
-		for (u32 i = 0; i < vertex_count; i++)
-			((video::S3DVertex *)(vertices + i * stride))->Pos *= scale;
-
-		buf->setDirty(scene::EBT_VERTEX);
-		buf->recalculateBoundingBox();
+		transformMeshBuffer(buf, [scale](video::S3DVertex *vertex) {
+			vertex->Pos *= scale;
+		});
 
 		// calculate total bounding box
 		if (j == 0)
@@ -140,14 +152,9 @@ void translateMesh(scene::IMesh *mesh, v3f vec)
 	u32 mc = mesh->getMeshBufferCount();
 	for (u32 j = 0; j < mc; j++) {
 		scene::IMeshBuffer *buf = mesh->getMeshBuffer(j);
-		const u32 stride = getVertexPitchFromType(buf->getVertexType());
-		u32 vertex_count = buf->getVertexCount();
-		u8 *vertices = (u8 *)buf->getVertices();
-		for (u32 i = 0; i < vertex_count; i++)
-			((video::S3DVertex *)(vertices + i * stride))->Pos += vec;
-
-		buf->setDirty(scene::EBT_VERTEX);
-		buf->recalculateBoundingBox();
+		transformMeshBuffer(buf, [vec](video::S3DVertex *vertex) {
+			vertex->Pos += vec;
+		});
 
 		// calculate total bounding box
 		if (j == 0)
@@ -330,44 +337,40 @@ bool checkMeshNormals(scene::IMesh *mesh)
 	return true;
 }
 
+template<class VertexType, class SMeshBufferType>
+static scene::IMeshBuffer *cloneMeshBuffer(scene::IMeshBuffer *mesh_buffer)
+{
+	auto *v = static_cast<VertexType *>(mesh_buffer->getVertices());
+	u16 *indices = mesh_buffer->getIndices();
+	auto *cloned_buffer = new SMeshBufferType();
+	cloned_buffer->append(v, mesh_buffer->getVertexCount(), indices,
+			mesh_buffer->getIndexCount());
+	// Rigidly animated meshes may have transformation matrices that need to be applied
+	if (auto *sbuf = dynamic_cast<scene::SSkinMeshBuffer *>(mesh_buffer)) {
+		transformMeshBuffer(cloned_buffer, [sbuf](video::S3DVertex *vertex) {
+			sbuf->Transformation.transformVect(vertex->Pos);
+			vertex->Normal = sbuf->Transformation.rotateAndScaleVect(vertex->Normal);
+			vertex->Normal.normalize();
+		});
+	}
+	return cloned_buffer;
+}
+
 scene::IMeshBuffer* cloneMeshBuffer(scene::IMeshBuffer *mesh_buffer)
 {
 	switch (mesh_buffer->getVertexType()) {
-	case video::EVT_STANDARD: {
-		video::S3DVertex *v = (video::S3DVertex *) mesh_buffer->getVertices();
-		u16 *indices = mesh_buffer->getIndices();
-		scene::SMeshBuffer *cloned_buffer = new scene::SMeshBuffer();
-		cloned_buffer->append(v, mesh_buffer->getVertexCount(), indices,
-			mesh_buffer->getIndexCount());
-		return cloned_buffer;
+	case video::EVT_STANDARD:
+		return cloneMeshBuffer<video::S3DVertex, scene::SMeshBuffer>(mesh_buffer);
+	case video::EVT_2TCOORDS:
+		return cloneMeshBuffer<video::S3DVertex2TCoords, scene::SMeshBufferLightMap>(mesh_buffer);
+	case video::EVT_TANGENTS:
+		return cloneMeshBuffer<video::S3DVertexTangents, scene::SMeshBufferTangents>(mesh_buffer);
 	}
-	case video::EVT_2TCOORDS: {
-		video::S3DVertex2TCoords *v =
-			(video::S3DVertex2TCoords *) mesh_buffer->getVertices();
-		u16 *indices = mesh_buffer->getIndices();
-		scene::SMeshBufferLightMap *cloned_buffer =
-			new scene::SMeshBufferLightMap();
-		cloned_buffer->append(v, mesh_buffer->getVertexCount(), indices,
-			mesh_buffer->getIndexCount());
-		return cloned_buffer;
-	}
-	case video::EVT_TANGENTS: {
-		video::S3DVertexTangents *v =
-			(video::S3DVertexTangents *) mesh_buffer->getVertices();
-		u16 *indices = mesh_buffer->getIndices();
-		scene::SMeshBufferTangents *cloned_buffer =
-			new scene::SMeshBufferTangents();
-		cloned_buffer->append(v, mesh_buffer->getVertexCount(), indices,
-			mesh_buffer->getIndexCount());
-		return cloned_buffer;
-	}
-	}
-	// This should not happen.
 	sanity_check(false);
 	return NULL;
 }
 
-scene::SMesh* cloneMesh(scene::IMesh *src_mesh)
+scene::SMesh* cloneStaticMesh(scene::IMesh *src_mesh)
 {
 	scene::SMesh* dst_mesh = new scene::SMesh();
 	for (u16 j = 0; j < src_mesh->getMeshBufferCount(); j++) {

src/client/mesh.h

@@ -93,10 +93,8 @@ void rotateMeshYZby (scene::IMesh *mesh, f64 degrees);
  */
 scene::IMeshBuffer* cloneMeshBuffer(scene::IMeshBuffer *mesh_buffer);
 
-/*
-	Clone the mesh.
-*/
-scene::SMesh* cloneMesh(scene::IMesh *src_mesh);
+/// Clone a mesh. For an animated mesh, this will clone the static pose.
+scene::SMesh* cloneStaticMesh(scene::IMesh *src_mesh);
 
 /*
 	Convert nodeboxes to mesh. Each tile goes into a different buffer.

src/client/wieldmesh.cpp

@@ -255,7 +255,7 @@ void WieldMeshSceneNode::setExtruded(const std::string &imagename,
 		dim = core::dimension2d<u32>(dim.Width, frame_height);
 	}
 	scene::IMesh *original = g_extrusion_mesh_cache->create(dim);
-	scene::SMesh *mesh = cloneMesh(original);
+	scene::SMesh *mesh = cloneStaticMesh(original);
 	original->drop();
 	//set texture
 	mesh->getMeshBuffer(0)->getMaterial().setTexture(0,
@@ -639,7 +639,7 @@ scene::SMesh *getExtrudedMesh(ITextureSource *tsrc,
 	// get mesh
 	core::dimension2d<u32> dim = texture->getSize();
 	scene::IMesh *original = g_extrusion_mesh_cache->create(dim);
-	scene::SMesh *mesh = cloneMesh(original);
+	scene::SMesh *mesh = cloneStaticMesh(original);
 	original->drop();
 
 	//set texture

src/nodedef.cpp

@@ -13,6 +13,7 @@
 #include "client/texturesource.h"
 #include "client/tile.h"
 #include <IMeshManipulator.h>
+#include <SMesh.h>
 #include <SkinnedMesh.h>
 #endif
 #include "log.h"
@@ -959,23 +960,28 @@ void ContentFeatures::updateTextures(ITextureSource *tsrc, IShaderSource *shdsrc
 		palette = tsrc->getPalette(palette_name);
 
 	if (drawtype == NDT_MESH && !mesh.empty()) {
-		// Read the mesh and apply scale
-		mesh_ptr = client->getMesh(mesh);
-		if (mesh_ptr) {
-			v3f scale = v3f(BS) * visual_scale;
-			scaleMesh(mesh_ptr, scale);
+		// Note: By freshly reading, we get an unencumbered mesh.
+		if (scene::IMesh *src_mesh = client->getMesh(mesh)) {
+			f32 mesh_scale = 1.0f;
+			if (auto *static_mesh = dynamic_cast<scene::SMesh *>(src_mesh)) {
+				mesh_ptr = static_mesh;
+				// Compatibility: Only apply BS scaling to static meshes (.obj). See #15811.
+				mesh_scale = 10.0f;
+			} else {
+				// We only want to consider static meshes from here on.
+				mesh_ptr = cloneStaticMesh(src_mesh);
+				src_mesh->drop();
+			}
+			scaleMesh(mesh_ptr, v3f(mesh_scale * visual_scale));
 			recalculateBoundingBox(mesh_ptr);
 			if (!checkMeshNormals(mesh_ptr)) {
+				// TODO this should be done consistently when the mesh is loaded
 				infostream << "ContentFeatures: recalculating normals for mesh "
 					<< mesh << std::endl;
 				meshmanip->recalculateNormals(mesh_ptr, true, false);
-			} else {
-				// Animation is not supported, but we need to reset it to
-				// default state if it is animated.
-				// Note: recalculateNormals() also does this hence the else-block
-				if (mesh_ptr->getMeshType() == scene::EAMT_SKINNED)
-					((scene::SkinnedMesh*) mesh_ptr)->resetAnimation();
 			}
+		} else {
+			mesh_ptr = nullptr;
 		}
 	}
 }

src/nodedef.h

@@ -342,7 +342,7 @@ struct ContentFeatures
 	enum NodeDrawType drawtype;
 	std::string mesh;
 #if CHECK_CLIENT_BUILD()
-	scene::IMesh *mesh_ptr; // mesh in case of mesh node
+	scene::SMesh *mesh_ptr; // mesh in case of mesh node
 	video::SColor minimap_color;
 #endif
 	float visual_scale; // Misc. scale parameter