xref: /dports/games/warzone2100/warzone2100/lib/ivis_opengl/imdload.cpp

/*
	This file is part of Warzone 2100.
	Copyright (C) 1999-2004  Eidos Interactive
	Copyright (C) 2005-2020  Warzone 2100 Project

	Warzone 2100 is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	Warzone 2100 is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with Warzone 2100; if not, write to the Free Software
	Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/

/*!
 * \file imdload.c
 *
 * Load IMD (.pie) files
 */

#include <string>
#include <unordered_map>

#include "lib/framework/frame.h"
#include "lib/framework/string_ext.h"
#include "lib/framework/frameresource.h"
#include "lib/framework/fixedpoint.h"
#include "lib/framework/file.h"
#include "lib/framework/physfs_ext.h"
#include "lib/ivis_opengl/piematrix.h"
#include "lib/ivis_opengl/pienormalize.h"
#include "lib/ivis_opengl/piestate.h"

#include "ivisdef.h" // for imd structures
#include "imd.h" // for imd structures
#include "tex.h" // texture page loading

#include <glm/vec4.hpp>
using Vector4f = glm::vec4;

// Scale animation numbers from int to float
#define INT_SCALE       1000

static std::unordered_map<std::string, iIMDShape> models;

static void iV_ProcessIMD(const WzString &filename, const char **ppFileData, const char *FileDataEnd);

iIMDShape::~iIMDShape()
{
	free(connectors);
	free(shadowEdgeList);
	for (auto* buffer : buffers)
	{
		delete buffer;
	}
}

void modelShutdown()
{
	models.clear();
}

void enumerateLoadedModels(const std::function<void (const std::string& modelName, iIMDShape& model)>& func)
{
	for (auto& keyvaluepair : models)
	{
		func(keyvaluepair.first, keyvaluepair.second);
	}
}

static bool tryLoad(const WzString &path, const WzString &filename)
{
	if (PHYSFS_exists(path + filename))
	{
		char *pFileData = nullptr, *fileEnd;
		UDWORD size = 0;
		if (!loadFile(WzString(path + filename).toUtf8().c_str(), &pFileData, &size))
		{
			debug(LOG_ERROR, "Failed to load model file: %s", WzString(path + filename).toUtf8().c_str());
			return false;
		}
		fileEnd = pFileData + size;
		const char *pFileDataPt = pFileData;
		iV_ProcessIMD(filename, (const char **)&pFileDataPt, fileEnd);
		free(pFileData);
		return true;
	}
	return false;
}

const std::string &modelName(iIMDShape *model)
{
	for (const auto &pair : models)
	{
		if (&pair.second == model)
		{
			return pair.first;
		}
	}
	ASSERT(false, "An IMD pointer could not be backtraced to a filename!");
	static std::string error;
	return error;
}

iIMDShape *modelGet(const WzString &filename)
{
	WzString name(filename.toLower());
	auto it = models.find(name.toStdString());
	if (it != models.end())
	{
		return &it->second; // cached
	}
	else if (tryLoad("structs/", name) || tryLoad("misc/", name) || tryLoad("effects/", name)
	         || tryLoad("components/prop/", name) || tryLoad("components/weapons/", name)
	         || tryLoad("components/bodies/", name) || tryLoad("features/", name)
	         || tryLoad("misc/micnum/", name) || tryLoad("misc/minum/", name) || tryLoad("misc/mivnum/", name) || tryLoad("misc/researchimds/", name))
	{
		return &models.at(name.toStdString());
	}
	debug(LOG_ERROR, "Could not find: %s", name.toUtf8().c_str());
	return nullptr;
}

static bool AtEndOfFile(const char *CurPos, const char *EndOfFile)
{
	while (*CurPos == 0x00 || *CurPos == 0x09 || *CurPos == 0x0a || *CurPos == 0x0d || *CurPos == 0x20)
	{
		CurPos++;
		if (CurPos >= EndOfFile)
		{
			return true;
		}
	}

	if (CurPos >= EndOfFile)
	{
		return true;
	}
	return false;
}


/*!
 * Load shape level polygons
 * \param ppFileData Pointer to the data (usually read from a file)
 * \param s Pointer to shape level
 * \return false on error (memory allocation failure/bad file format), true otherwise
 */
static bool _imd_load_polys(const WzString &filename, const char **ppFileData, iIMDShape *s, int pieVersion, const uint32_t npoints)
{
	const char *pFileData = *ppFileData;

	s->numFrames = 0;
	s->animInterval = 0;

	for (unsigned i = 0; i < s->polys.size(); i++)
	{
		iIMDPoly *poly = &s->polys[i];
		unsigned int flags, npnts;
		int cnt;

		if (sscanf(pFileData, "%x %u%n", &flags, &npnts, &cnt) != 2)
		{
			debug(LOG_ERROR, "(_load_polys) [poly %u] error loading flags and npoints", i);
		}
		pFileData += cnt;

		poly->flags = flags;
		ASSERT_OR_RETURN(false, npnts == 3, "Invalid polygon size (%d)", npnts);
		if (sscanf(pFileData, "%" PRIu32 "%" PRIu32 "%" PRIu32 "%n", &poly->pindex[0], &poly->pindex[1], &poly->pindex[2], &cnt) != 3)
		{
			debug(LOG_ERROR, "failed reading triangle, point %d", i);
			return false;
		}
		pFileData += cnt;

		// sanity check
		for (size_t pIdx = 0; pIdx < 3; pIdx++)
		{
			ASSERT_OR_RETURN(false, (poly->pindex[pIdx] < npoints), "Point index (%" PRIu32 ") exceeds max index (%" PRIu32 ")", poly->pindex[pIdx], (npoints - 1));
		}

		// calc poly normal
		{
			Vector3f p0, p1, p2;

			//assumes points already set
			p0.x = s->points[poly->pindex[0]].x;
			p0.y = s->points[poly->pindex[0]].y;
			p0.z = s->points[poly->pindex[0]].z;

			p1.x = s->points[poly->pindex[1]].x;
			p1.y = s->points[poly->pindex[1]].y;
			p1.z = s->points[poly->pindex[1]].z;

			p2.x = s->points[poly->pindex[2]].x;
			p2.y = s->points[poly->pindex[2]].y;
			p2.z = s->points[poly->pindex[2]].z;

			poly->normal = pie_SurfaceNormal3fv(p0, p1, p2);
		}

		// texture coord routine
		if (poly->flags & iV_IMD_TEX)
		{
			int nFrames, framesPerLine, frame, pbRate;
			float tWidth, tHeight;

			if (poly->flags & iV_IMD_TEXANIM)
			{
				if (sscanf(pFileData, "%d %d %f %f%n", &nFrames, &pbRate, &tWidth, &tHeight, &cnt) != 4)
				{
					debug(LOG_ERROR, "(_load_polys) [poly %u] error reading texanim data", i);
					return false;
				}
				pFileData += cnt;

				ASSERT(tWidth > 0.0001f, "%s: texture width = %f", filename.toUtf8().c_str(), tWidth);
				ASSERT(tHeight > 0.f, "%s: texture height = %f (width=%f)", filename.toUtf8().c_str(), tHeight, tWidth);
				ASSERT(nFrames > 1, "%s: animation frames = %d", filename.toUtf8().c_str(), nFrames);
				ASSERT(pbRate > 0, "%s: animation interval = %d ms", filename.toUtf8().c_str(), pbRate);

				/* Must have same number of frames and same playback rate for all polygons */
				if (s->numFrames == 0)
				{
					s->numFrames = nFrames;
					s->animInterval = pbRate;
				}
				else
				{
					ASSERT(s->numFrames == nFrames,
					       "%s: varying number of frames within one PIE level: %d != %d",
					       filename.toUtf8().c_str(), nFrames, s->numFrames);
					ASSERT(s->animInterval == pbRate,
					       "%s: varying animation intervals within one PIE level: %d != %d",
					       filename.toUtf8().c_str(), pbRate, s->animInterval);
				}

				poly->texAnim.x = tWidth;
				poly->texAnim.y = tHeight;

				if (pieVersion != PIE_FLOAT_VER)
				{
					poly->texAnim.x /= OLD_TEXTURE_SIZE_FIX;
					poly->texAnim.y /= OLD_TEXTURE_SIZE_FIX;
				}
				framesPerLine = 1 / poly->texAnim.x;
			}
			else
			{
				nFrames = 1;
				framesPerLine = 1;
				pbRate = 1;
				tWidth = 0.f;
				tHeight = 0.f;
				poly->texAnim.x = 0;
				poly->texAnim.y = 0;
			}

			poly->texCoord.resize(nFrames * 3);
			for (unsigned j = 0; j < 3; j++)
			{
				float VertexU, VertexV;

				if (sscanf(pFileData, "%f %f%n", &VertexU, &VertexV, &cnt) != 2)
				{
					debug(LOG_ERROR, "(_load_polys) [poly %u] error reading tex outline", i);
					return false;
				}
				pFileData += cnt;

				if (pieVersion != PIE_FLOAT_VER)
				{
					VertexU /= OLD_TEXTURE_SIZE_FIX;
					VertexV /= OLD_TEXTURE_SIZE_FIX;
				}

				for (frame = 0; frame < nFrames; frame++)
				{
					const float uFrame = (frame % framesPerLine) * poly->texAnim.x;
					const float vFrame = (frame / framesPerLine) * poly->texAnim.y;
					Vector2f *c = &poly->texCoord[frame * 3 + j];

					c->x = VertexU + uFrame;
					c->y = VertexV + vFrame;
				}
			}
		}
		else
		{
			ASSERT_OR_RETURN(false, !(poly->flags & iV_IMD_TEXANIM), "Polygons with texture animation must have textures!");
			poly->texCoord.clear();
		}
	}

	*ppFileData = pFileData;

	return true;
}


static bool ReadPoints(const char **ppFileData, iIMDShape &s)
{
	const char *pFileData = *ppFileData;
	int cnt;

	for (Vector3f &points : s.points)
	{
		if (sscanf(pFileData, "%f %f %f%n", &points.x, &points.y, &points.z, &cnt) != 3)
		{
			debug(LOG_ERROR, "File corrupt - could not read points");
			return false;
		}
		pFileData += cnt;
	}

	*ppFileData = pFileData;

	return true;
}

static void _imd_calc_bounds(iIMDShape &s)
{
	int32_t xmax, ymax, zmax;
	double dx, dy, dz, rad_sq, rad, old_to_p_sq, old_to_p, old_to_new;
	double xspan, yspan, zspan, maxspan;
	Vector3f dia1, dia2, cen;
	Vector3f vxmin(0, 0, 0), vymin(0, 0, 0), vzmin(0, 0, 0),
	         vxmax(0, 0, 0), vymax(0, 0, 0), vzmax(0, 0, 0);

	s.max.x = s.max.y = s.max.z = -FP12_MULTIPLIER;
	s.min.x = s.min.y = s.min.z = FP12_MULTIPLIER;

	vxmax.x = vymax.y = vzmax.z = -FP12_MULTIPLIER;
	vxmin.x = vymin.y = vzmin.z = FP12_MULTIPLIER;

	// set up bounding data for minimum number of vertices
	for (const Vector3f &p : s.points)
	{
		if (p.x > s.max.x)
		{
			s.max.x = p.x;
		}
		if (p.x < s.min.x)
		{
			s.min.x = p.x;
		}

		if (p.y > s.max.y)
		{
			s.max.y = p.y;
		}
		if (p.y < s.min.y)
		{
			s.min.y = p.y;
		}

		if (p.z > s.max.z)
		{
			s.max.z = p.z;
		}
		if (p.z < s.min.z)
		{
			s.min.z = p.z;
		}

		// for tight sphere calculations
		if (p.x < vxmin.x)
		{
			vxmin.x = p.x;
			vxmin.y = p.y;
			vxmin.z = p.z;
		}

		if (p.x > vxmax.x)
		{
			vxmax.x = p.x;
			vxmax.y = p.y;
			vxmax.z = p.z;
		}

		if (p.y < vymin.y)
		{
			vymin.x = p.x;
			vymin.y = p.y;
			vymin.z = p.z;
		}

		if (p.y > vymax.y)
		{
			vymax.x = p.x;
			vymax.y = p.y;
			vymax.z = p.z;
		}

		if (p.z < vzmin.z)
		{
			vzmin.x = p.x;
			vzmin.y = p.y;
			vzmin.z = p.z;
		}

		if (p.z > vzmax.z)
		{
			vzmax.x = p.x;
			vzmax.y = p.y;
			vzmax.z = p.z;
		}
	}

	// no need to scale an IMD shape (only FSD)
	xmax = MAX(s.max.x, -s.min.x);
	ymax = MAX(s.max.y, -s.min.y);
	zmax = MAX(s.max.z, -s.min.z);

	s.radius = MAX(xmax, MAX(ymax, zmax));
	s.sradius = sqrtf(xmax * xmax + ymax * ymax + zmax * zmax);

// START: tight bounding sphere

	// set xspan = distance between 2 points xmin & xmax (squared)
	dx = vxmax.x - vxmin.x;
	dy = vxmax.y - vxmin.y;
	dz = vxmax.z - vxmin.z;
	xspan = dx * dx + dy * dy + dz * dz;

	// same for yspan
	dx = vymax.x - vymin.x;
	dy = vymax.y - vymin.y;
	dz = vymax.z - vymin.z;
	yspan = dx * dx + dy * dy + dz * dz;

	// and ofcourse zspan
	dx = vzmax.x - vzmin.x;
	dy = vzmax.y - vzmin.y;
	dz = vzmax.z - vzmin.z;
	zspan = dx * dx + dy * dy + dz * dz;

	// set points dia1 & dia2 to maximally separated pair
	// assume xspan biggest
	dia1 = vxmin;
	dia2 = vxmax;
	maxspan = xspan;

	if (yspan > maxspan)
	{
		maxspan = yspan;
		dia1 = vymin;
		dia2 = vymax;
	}

	if (zspan > maxspan)
	{
		dia1 = vzmin;
		dia2 = vzmax;
	}

	// dia1, dia2 diameter of initial sphere
	cen.x = (dia1.x + dia2.x) / 2.;
	cen.y = (dia1.y + dia2.y) / 2.;
	cen.z = (dia1.z + dia2.z) / 2.;

	// calc initial radius
	dx = dia2.x - cen.x;
	dy = dia2.y - cen.y;
	dz = dia2.z - cen.z;

	rad_sq = dx * dx + dy * dy + dz * dz;
	rad = sqrt((double)rad_sq);

	// second pass (find tight sphere)
	for (const Vector3f &p : s.points)
	{
		dx = p.x - cen.x;
		dy = p.y - cen.y;
		dz = p.z - cen.z;
		old_to_p_sq = dx * dx + dy * dy + dz * dz;

		// do r**2 first
		if (old_to_p_sq > rad_sq)
		{
			// this point outside current sphere
			old_to_p = sqrt((double)old_to_p_sq);
			// radius of new sphere
			rad = (rad + old_to_p) / 2.;
			// rad**2 for next compare
			rad_sq = rad * rad;
			old_to_new = old_to_p - rad;
			// centre of new sphere
			cen.x = (rad * cen.x + old_to_new * p.x) / old_to_p;
			cen.y = (rad * cen.y + old_to_new * p.y) / old_to_p;
			cen.z = (rad * cen.z + old_to_new * p.z) / old_to_p;
		}
	}

	s.ocen = cen;

// END: tight bounding sphere
}

static bool _imd_load_points(const char **ppFileData, iIMDShape &s, uint32_t npoints)
{
	//load the points then pass through a second time to setup bounding datavalues
	s.points.resize(npoints);

	// Read in points and remove duplicates (!)
	if (ReadPoints(ppFileData, s) == false)
	{
		s.points.clear();
		return false;
	}

	_imd_calc_bounds(s);

	return true;
}


/*!
 * Load shape level connectors
 * \param ppFileData Pointer to the data (usually read from a file)
 * \param s Pointer to shape level
 * \return false on error (memory allocation failure/bad file format), true otherwise
 * \pre ppFileData loaded
 * \pre s allocated
 * \pre s->nconnectors set
 * \post s->connectors allocated
 */
bool _imd_load_connectors(const char **ppFileData, iIMDShape &s)
{
	const char *pFileData = *ppFileData;
	int cnt;
	Vector3i *p = nullptr, newVector(0, 0, 0);

	s.connectors = (Vector3i *)malloc(sizeof(Vector3i) * s.nconnectors);
	for (p = s.connectors; p < s.connectors + s.nconnectors; p++)
	{
		if (sscanf(pFileData, "%d %d %d%n",                         &newVector.x, &newVector.y, &newVector.z, &cnt) != 3 &&
		    sscanf(pFileData, "%d%*[.0-9] %d%*[.0-9] %d%*[.0-9]%n", &newVector.x, &newVector.y, &newVector.z, &cnt) != 3)
		{
			debug(LOG_ERROR, "(_load_connectors) file corrupt -M");
			return false;
		}
		pFileData += cnt;
		*p = newVector;
	}

	*ppFileData = pFileData;

	return true;
}

// performance hack
static std::vector<gfx_api::gfxFloat> vertices;
static std::vector<gfx_api::gfxFloat> normals;
static std::vector<gfx_api::gfxFloat> texcoords;
static std::vector<gfx_api::gfxFloat> tangents;
static std::vector<gfx_api::gfxFloat> bitangents;
static std::vector<uint16_t> indices; // size is npolys * 3 * numFrames
static uint16_t vertexCount = 0;

static bool ReadNormals(const char **ppFileData, std::vector<Vector3f> &pie_level_normals)
{
   const char *pFileData = *ppFileData;
   int dataCnt;

   for (Vector3f &normal : pie_level_normals)
   {
	   if (sscanf(pFileData, "%f %f %f%n", &normal.x, &normal.y, &normal.z, &dataCnt) != 3)
	   {
		   debug(LOG_ERROR, "File corrupt - could not read normals");
		   return false;
	   }
	   pFileData += dataCnt;
   }

   *ppFileData = pFileData;

   return true;
}

static bool _imd_load_normals(const char **ppFileData, std::vector<Vector3f> &pie_level_normals, uint32_t num_normal_lines)
{
   // We only support triangles!
   pie_level_normals.resize(static_cast<size_t>(num_normal_lines * 3));

   if (ReadNormals(ppFileData, pie_level_normals) == false)
   {
	   pie_level_normals.clear();
	   return false;
   }

   return true;
}

static inline uint16_t addVertex(iIMDShape &s, size_t i, const iIMDPoly *p, int frameidx, size_t polyIdx, std::vector<Vector3f> &pie_level_normals)
{
	// if texture animation flag is present, fetch animation coordinates for this polygon
	// otherwise just show the first set of texel coordinates
	int frame = (p->flags & iV_IMD_TEXANIM) ? frameidx : 0;

	const Vector3f* normal;

 	// Do not weld for for models with normals, those are presumed to be correct. Otherwise, it will break tangents
 	if (pie_level_normals.empty())
 	{
		normal = &p->normal;
		// See if we already have this defined, if so, return reference to it.
		for (uint16_t j = 0; j < vertexCount; j++)
		{
			if (texcoords[j * 2 + 0] == p->texCoord[frame * 3 + i].x
 			    && texcoords[j * 2 + 1] == p->texCoord[frame * 3 + i].y
 			    && vertices[j * 3 + 0] == s.points[p->pindex[i]].x
 			    && vertices[j * 3 + 1] == s.points[p->pindex[i]].y
 			    && vertices[j * 3 + 2] == s.points[p->pindex[i]].z
 			    && normals[j * 3 + 0] == normal->x
 			    && normals[j * 3 + 1] == normal->y
 			    && normals[j * 3 + 2] == normal->z)
 			{
 				return j;
 			}
		}
	}
	else
	{
		normal = &pie_level_normals[polyIdx * 3 + i];
	}

	// We don't have it, add it.
	normals.emplace_back(normal->x);
 	normals.emplace_back(normal->y);
 	normals.emplace_back(normal->z);
	texcoords.emplace_back(p->texCoord[frame * 3 + i].x);
	texcoords.emplace_back(p->texCoord[frame * 3 + i].y);
	vertices.emplace_back(s.points[p->pindex[i]].x);
	vertices.emplace_back(s.points[p->pindex[i]].y);
	vertices.emplace_back(s.points[p->pindex[i]].z);
	vertexCount++;

	return vertexCount - 1;
}

void calculateTangentsForTriangle(const uint16_t ia, const uint16_t ib, const uint16_t ic)
{
   // This will work as long as vecs are packed (which is default in glm)
   const Vector3f* verticesAsVec3 = reinterpret_cast<const Vector3f*>(vertices.data());
   const Vector2f* texcoordsAsVec2 = reinterpret_cast<const Vector2f*>(texcoords.data());
   Vector4f* tangentsAsVec4 = reinterpret_cast<Vector4f*>(tangents.data());
   Vector3f* bitangentsAsVec3 = reinterpret_cast<Vector3f*>(bitangents.data());

   // Shortcuts for vertices
   const Vector3f& va(verticesAsVec3[ia]);
   const Vector3f& vb(verticesAsVec3[ib]);
   const Vector3f& vc(verticesAsVec3[ic]);

   // Shortcuts for UVs
   const Vector2f& uva(texcoordsAsVec2[ia]);
   const Vector2f& uvb(texcoordsAsVec2[ib]);
   const Vector2f& uvc(texcoordsAsVec2[ic]);

   // Edges of the triangle : postion delta
   const Vector3f deltaPos1 = vb - va;
   const Vector3f deltaPos2 = vc - va;

   // UV delta
   const Vector2f deltaUV1 = uvb - uva;
   const Vector2f deltaUV2 = uvc - uva;

   // check for nan
   float r = deltaUV1.x * deltaUV2.y - deltaUV1.y * deltaUV2.x;
   if (r != 0.f)
	   r = 1.f / r;

   const Vector4f tangent(Vector3f(deltaPos1 * deltaUV2.y - deltaPos2 * deltaUV1.y) * r, 0.f);
   const Vector3f bitangent(Vector3f(deltaPos2 * deltaUV1.x - deltaPos1 * deltaUV2.x) * r);

   tangentsAsVec4[ia] += tangent;
   tangentsAsVec4[ib] += tangent;
   tangentsAsVec4[ic] += tangent;

   bitangentsAsVec3[ia] += bitangent;
   bitangentsAsVec3[ib] += bitangent;
   bitangentsAsVec3[ic] += bitangent;
}

void finishTangentsGeneration()
{
   // This will work as long as vecs are packed (which is default in glm)
   const Vector3f* normalsAsVec3 = reinterpret_cast<const Vector3f*>(normals.data());
   Vector4f* tangentsAsVec4 = reinterpret_cast<Vector4f*>(tangents.data());
   const Vector3f* bitangentsAsVec3 = reinterpret_cast<const Vector3f*>(bitangents.data());

   Vector3f t;

   for (auto i = 0; i < vertexCount; ++i)
   {
	   const Vector3f& n = normalsAsVec3[i];
	   const Vector3f& b = bitangentsAsVec3[i];
	   t = tangentsAsVec4[i].xyz();

	   // Gram-Schmidt orthogonalize
	   t = glm::normalize(t - n * glm::dot(n, t));

	   // Calculate handedness
	   if (glm::dot(glm::cross(n, t), b) < 0.f)
	   {
		   tangentsAsVec4[i] = Vector4f(-t, 1.f);
	   }
	   else
	   {
		   tangentsAsVec4[i] = Vector4f(-t, -1.f);
	   }
   }
}


/*!
 * Load shape levels recursively
 * \param ppFileData Pointer to the data (usually read from a file)
 * \param FileDataEnd ???
 * \param nlevels Number of levels to load
 * \return pointer to iFSDShape structure (or NULL on error)
 * \pre ppFileData loaded
 * \post s allocated
 */
static iIMDShape *_imd_load_level(const WzString &filename, const char **ppFileData, const char *FileDataEnd, int nlevels, int pieVersion, int level)
{
	const char *pFileData = *ppFileData;
	char buffer[PATH_MAX] = {'\0'};
	int cnt = 0, n = 0, scanResult = 0;
	float dummy;

	if (nlevels == 0)
	{
		return nullptr;
	}

	// insert model
	std::string key = filename.toStdString();
	if (level > 0)
	{
		key += "_" + std::to_string(level);
	}
	ASSERT(models.count(key) == 0, "Duplicate model load for %s!", key.c_str());
	iIMDShape &s = models[key]; // create entry and return reference
	s.pShadowPoints = &s.points;
	s.pShadowPolys = &s.polys;

	scanResult = sscanf(pFileData, "%255s %n", buffer, &cnt);
	ASSERT_OR_RETURN(nullptr, scanResult == 1, "Bad directive following LEVEL");

	// Optionally load and ignore deprecated MATERIALS directive
	if (strcmp(buffer, "MATERIALS") == 0)
	{
		scanResult = sscanf(pFileData, "%255s %f %f %f %f %f %f %f %f %f %f%n", buffer, &dummy, &dummy, &dummy, &dummy,
		           &dummy, &dummy, &dummy, &dummy, &dummy, &dummy, &cnt);
		ASSERT_OR_RETURN(nullptr, scanResult == 11, "Bad MATERIALS directive");
		debug(LOG_WARNING, "MATERIALS directive no longer supported!");
		pFileData += cnt;
	}
	else if (strcmp(buffer, "SHADERS") == 0)
	{
		char vertex[PATH_MAX], fragment[PATH_MAX];

		if (sscanf(pFileData, "%255s %255s %255s%n", buffer, vertex, fragment, &cnt) != 3)
		{
			debug(LOG_ERROR, "%s shader corrupt: %s", filename.toUtf8().c_str(), buffer);
			return nullptr;
		}
		debug(LOG_WARNING, "SHADERS directive no longer supported!");
		pFileData += cnt;
	}

	uint32_t npoints = 0;
	if (sscanf(pFileData, "%255s %" PRIu32 "%n", buffer, &npoints, &cnt) != 2)
	{
		debug(LOG_ERROR, "_imd_load_level(2): file corrupt");
		return nullptr;
	}
	pFileData += cnt;

	// load points

	ASSERT_OR_RETURN(nullptr, strcmp(buffer, "POINTS") == 0, "Expecting 'POINTS' directive, got: %s", buffer);

	_imd_load_points(&pFileData, s, npoints);

	uint32_t npolys = 0;
	if (sscanf(pFileData, "%255s %" PRIu32 "%n", buffer, &npolys, &cnt) != 2)
	{
		debug(LOG_ERROR, "_imd_load_level(3): file corrupt");
		return nullptr;
	}
	pFileData += cnt;

	std::vector<Vector3f> pie_level_normals;

	// It could be optional normals directive
 	if (strcmp(buffer, "NORMALS") == 0)
 	{
 		_imd_load_normals(&pFileData, pie_level_normals, npolys);

 		// Attemps to read polys again
 		if (sscanf(pFileData, "%255s %" PRIu32 "%n", buffer, &npolys, &cnt) != 2)
 		{
 			debug(LOG_ERROR, "_imd_load_level(3a): file corrupt");
 			return nullptr;
 		}
		debug(LOG_3D, "imd[_load_level] = normals %d", static_cast<int>(pie_level_normals.size()));
 		pFileData += cnt;
 	}

	s.polys.resize(npolys);

	ASSERT_OR_RETURN(nullptr, strcmp(buffer, "POLYGONS") == 0, "Expecting 'POLYGONS' directive, got: %s", buffer);

	_imd_load_polys(filename, &pFileData, &s, pieVersion, npoints);

	// optional stuff : levels, object animations, connectors, shadow points + polys
	s.objanimframes = 0;
	while (!AtEndOfFile(pFileData, FileDataEnd)) // check for end of file (give or take white space)
	{
		// Scans in the line ... if we don't get 2 parameters then quit
		if (sscanf(pFileData, "%255s %d%n", buffer, &n, &cnt) != 2)
		{
			break;
		}
		pFileData += cnt;

		if (strcmp(buffer, "LEVEL") == 0)	// check for next level
		{
			debug(LOG_3D, "imd[_load_level] = npoints %" PRIu32 ", npolys %" PRIu32 "", npoints, npolys);
			s.next = _imd_load_level(filename, &pFileData, FileDataEnd, nlevels - 1, pieVersion, level + 1);
		}
		else if (strcmp(buffer, "CONNECTORS") == 0)
		{
			//load connector stuff
			s.nconnectors = n;
			_imd_load_connectors(&pFileData, s);
		}
		else if (strcmp(buffer, "ANIMOBJECT") == 0)
		{
			s.objanimtime = n;
			if (sscanf(pFileData, "%d %d%n", &s.objanimcycles, &s.objanimframes, &cnt) != 2)
			{
				debug(LOG_ERROR, "%s bad ANIMOBJ: %s", filename.toUtf8().c_str(), pFileData);
				return nullptr;
			}
			pFileData += cnt;
			s.objanimdata.resize(s.objanimframes);
			for (int i = 0; i < s.objanimframes; i++)
			{
				int frame;
				Vector3i pos(0, 0, 0), rot(0, 0, 0);

				if (sscanf(pFileData, "%d %d %d %d %d %d %d %f %f %f%n",
				           &frame, &pos.x, &pos.y, &pos.z, &rot.x, &rot.y, &rot.z,
				           &s.objanimdata[i].scale.x, &s.objanimdata[i].scale.y, &s.objanimdata[i].scale.z, &cnt) != 10)
				{
					debug(LOG_ERROR, "%s: Invalid object animation level %d, line %d, frame %d", filename.toUtf8().c_str(), level, i, frame);
				}
				ASSERT(frame == i, "%s: Invalid frame enumeration object animation (level %d) %d: %d", filename.toUtf8().c_str(), level, i, frame);
				s.objanimdata[i].pos.x = pos.x / INT_SCALE;
				s.objanimdata[i].pos.y = pos.z / INT_SCALE;
				s.objanimdata[i].pos.z = pos.y / INT_SCALE;
				s.objanimdata[i].rot.pitch = -(rot.x * DEG_1 / INT_SCALE);
				s.objanimdata[i].rot.direction = -(rot.z * DEG_1 / INT_SCALE);
				s.objanimdata[i].rot.roll = -(rot.y * DEG_1 / INT_SCALE);
				pFileData += cnt;
			}
		}
		else if (strcmp(buffer, "SHADOWPOINTS") == 0)
		{
			ASSERT_OR_RETURN(nullptr, n > 0, "Invalid 'SHADOW_POINTS' count, got: %d", n);
			uint32_t nShadowPoints = static_cast<uint32_t>(n);

			iIMDShape tmpShadowShape;
			_imd_load_points(&pFileData, tmpShadowShape, nShadowPoints);

			s.altShadowPoints = std::move(tmpShadowShape.points);
			s.pShadowPoints = &s.altShadowPoints;
		}
		else if (strcmp(buffer, "SHADOWPOLYGONS") == 0)
		{
			ASSERT_OR_RETURN(nullptr, s.altShadowPoints.size() > 0, "'SHADOW_POLYGONS' must follow a non-empty SHADOW_POINTS section");
			ASSERT_OR_RETURN(nullptr, n > 0, "Invalid 'SHADOW_POLYGONS' count, got: %d", n);
			uint32_t nShadowPolys = static_cast<uint32_t>(n);

			iIMDShape tmpShadowShape;
			tmpShadowShape.polys.resize(nShadowPolys);
			_imd_load_polys(filename, &pFileData, &tmpShadowShape, PIE_FLOAT_VER, static_cast<uint32_t>(s.altShadowPoints.size()));

			s.altShadowPolys = std::move(tmpShadowShape.polys);
			s.pShadowPolys = &s.altShadowPolys;
		}
		else
		{
			debug(LOG_ERROR, "(_load_level) unexpected directive %s %d", buffer, n);
			break;
		}
	}

	// Sanity checks
 	if (!pie_level_normals.empty())
 	{
 		if (s.polys.size() * 3 != pie_level_normals.size())
 		{
 			debug(LOG_ERROR, "imd[_load_level] = got %" PRIu32 " npolys, but there are only %zu normals! Discarding normals...",
 			      npolys, pie_level_normals.size());
 			// This will force usage of calculated normals in addVertex
 			pie_level_normals.clear();
 		}
 	}
	if (!s.altShadowPoints.empty())
	{
		if (s.altShadowPolys.empty())
		{
			debug(LOG_ERROR, "imd[_load_level] = %zu SHADOWPOINTS specified, but there are no SHADOWPOLYGONS! Discarding shadow points...",
				  s.altShadowPoints.size());
			s.altShadowPoints.clear();
			s.altShadowPolys.clear();
			s.pShadowPoints = &s.points;
			s.pShadowPolys = &s.polys;
		}
	}

	// FINALLY, massage the data into what can stream directly to OpenGL
	vertexCount = 0;
	for (int k = 0; k < MAX(1, s.numFrames); k++)
	{
		// Go through all polygons for each frame
		for (size_t npol = 0; npol < s.polys.size(); ++npol)
		{
			const iIMDPoly& p = s.polys[npol];
			// Do we already have the vertex data for this polygon?
			indices.emplace_back(addVertex(s, 0, &p, k, npol, pie_level_normals));
 			indices.emplace_back(addVertex(s, 1, &p, k, npol, pie_level_normals));
 			indices.emplace_back(addVertex(s, 2, &p, k, npol, pie_level_normals));
		}
	}

	s.vertexCount = vertexCount;

	// Tangents are optional, only if normals were loaded and passed sanity check above
 	if (!pie_level_normals.empty())
 	{
 		tangents.resize(vertexCount * 4);
 		bitangents.resize(vertexCount * 3);

 		for (size_t i = 0; i < indices.size(); i += 3)
 			calculateTangentsForTriangle(indices[i], indices[i+1], indices[i+2]);
 		finishTangentsGeneration();

 		if (!tangents.empty())
 		{
 			if (!s.buffers[VBO_TANGENT])
 				s.buffers[VBO_TANGENT] = gfx_api::context::get().create_buffer_object(gfx_api::buffer::usage::vertex_buffer);
 			s.buffers[VBO_TANGENT]->upload(tangents.size() * sizeof(gfx_api::gfxFloat), tangents.data());
 		}
 	}

	if (!s.buffers[VBO_VERTEX])
		s.buffers[VBO_VERTEX] = gfx_api::context::get().create_buffer_object(gfx_api::buffer::usage::vertex_buffer);
	s.buffers[VBO_VERTEX]->upload(vertices.size() * sizeof(gfx_api::gfxFloat), vertices.data());

	if (!s.buffers[VBO_NORMAL])
		s.buffers[VBO_NORMAL] = gfx_api::context::get().create_buffer_object(gfx_api::buffer::usage::vertex_buffer);
	s.buffers[VBO_NORMAL]->upload(normals.size() * sizeof(gfx_api::gfxFloat), normals.data());

	if (!s.buffers[VBO_INDEX])
		s.buffers[VBO_INDEX] = gfx_api::context::get().create_buffer_object(gfx_api::buffer::usage::index_buffer);
	s.buffers[VBO_INDEX]->upload(indices.size() * sizeof(uint16_t), indices.data());

	if (!s.buffers[VBO_TEXCOORD])
		s.buffers[VBO_TEXCOORD] = gfx_api::context::get().create_buffer_object(gfx_api::buffer::usage::vertex_buffer);
	s.buffers[VBO_TEXCOORD]->upload(texcoords.size() * sizeof(gfx_api::gfxFloat), texcoords.data());

	indices.resize(0);
	vertices.resize(0);
	texcoords.resize(0);
	normals.resize(0);
	tangents.resize(0);
	bitangents.resize(0);

	*ppFileData = pFileData;

	return &s;
}

/*!
 * Load ppFileData into a shape
 * \param ppFileData Data from the IMD file
 * \param FileDataEnd Endpointer
 * \return The shape, constructed from the data read
 */
// ppFileData is incremented to the end of the file on exit!
static void iV_ProcessIMD(const WzString &filename, const char **ppFileData, const char *FileDataEnd)
{
	const char *pFileData = *ppFileData;
	char buffer[PATH_MAX], texfile[PATH_MAX], normalfile[PATH_MAX], specfile[PATH_MAX];
	int cnt, nlevels, interpolate;
	UDWORD level;
	int32_t imd_version;
	uint32_t imd_flags;
	bool bTextured = false;
	bool readInterpolate = false;
	iIMDShape *objanimpie[ANIM_EVENT_COUNT];

	memset(normalfile, 0, sizeof(normalfile));
	memset(specfile, 0, sizeof(specfile));

	if (sscanf(pFileData, "%255s %d%n", buffer, &imd_version, &cnt) != 2)
	{
		debug(LOG_ERROR, "%s: bad PIE version: (%s)", filename.toUtf8().c_str(), buffer);
		assert(false);
		return;
	}
	pFileData += cnt;

	if (strcmp(PIE_NAME, buffer) != 0)
	{
		debug(LOG_ERROR, "%s: Not an IMD file (%s %d)", filename.toUtf8().c_str(), buffer, imd_version);
		return;
	}

	//Now supporting version PIE_VER and PIE_FLOAT_VER files
	if (imd_version != PIE_VER && imd_version != PIE_FLOAT_VER)
	{
		debug(LOG_ERROR, "%s: Version %d not supported", filename.toUtf8().c_str(), imd_version);
		return;
	}

	// Read flag
	if (sscanf(pFileData, "%255s %x%n", buffer, &imd_flags, &cnt) != 2)
	{
		debug(LOG_ERROR, "%s: bad flags: %s", filename.toUtf8().c_str(), buffer);
		return;
	}
	pFileData += cnt;

	// Read interpolation -- optional
	if (sscanf(pFileData, "%255s %d%n", buffer, &interpolate, &cnt) != 2)
	{
		debug(LOG_ERROR, "%s: Expecting INTERPOLATE: %s", filename.toUtf8().c_str(), buffer);
		return;
	}
	if (strncmp(buffer, "INTERPOLATE", 11) == 0)
	{
		readInterpolate = true;
		pFileData += cnt;
	}

	/* This can be either texture or levels */
	if (sscanf(pFileData, "%255s %d%n", buffer, &nlevels, &cnt) != 2)
	{
		debug(LOG_ERROR, "%s: Expecting TEXTURE or LEVELS: %s", filename.toUtf8().c_str(), buffer);
		return;
	}
	pFileData += cnt;

	// get texture page if specified
	if (strncmp(buffer, "TEXTURE", 7) == 0)
	{
		int i, pwidth, pheight;
		char ch, texType[PATH_MAX];

		/* the first parameter for textures is always ignored; which is why we ignore
		 * nlevels read in above */
		ch = *pFileData++;

		// Run up to the dot or till the buffer is filled. Leave room for the extension.
		for (i = 0; i < PATH_MAX - 5 && (ch = *pFileData++) != '\0' && ch != '.'; ++i)
		{
			texfile[i] = ch;
		}
		texfile[i] = '\0';

		if (sscanf(pFileData, "%255s%n", texType, &cnt) != 1)
		{
			debug(LOG_ERROR, "%s: Texture info corrupt: %s", filename.toUtf8().c_str(), buffer);
			return;
		}
		pFileData += cnt;

		if (strcmp(texType, "png") != 0)
		{
			debug(LOG_ERROR, "%s: Only png textures supported", filename.toUtf8().c_str());
			return;
		}
		sstrcat(texfile, ".png");

		if (sscanf(pFileData, "%d %d%n", &pwidth, &pheight, &cnt) != 2)
		{
			debug(LOG_ERROR, "%s: Bad texture size: %s", filename.toUtf8().c_str(), buffer);
			return;
		}
		pFileData += cnt;

		/* Now read in LEVELS directive */
		if (sscanf(pFileData, "%255s %d%n", buffer, &nlevels, &cnt) != 2)
		{
			debug(LOG_ERROR, "%s: Bad levels info: %s", filename.toUtf8().c_str(), buffer);
			return;
		}
		pFileData += cnt;

		bTextured = true;
	}

	if (strncmp(buffer, "NORMALMAP", 9) == 0)
	{
		char ch, texType[PATH_MAX];
		int i;

		/* the first parameter for textures is always ignored; which is why we ignore
		 * nlevels read in above */
		ch = *pFileData++;

		// Run up to the dot or till the buffer is filled. Leave room for the extension.
		for (i = 0; i < PATH_MAX - 5 && (ch = *pFileData++) != '\0' && ch != '.'; ++i)
		{
			normalfile[i] = ch;
		}
		normalfile[i] = '\0';

		if (sscanf(pFileData, "%255s%n", texType, &cnt) != 1)
		{
			debug(LOG_ERROR, "%s: Normal map info corrupt: %s", filename.toUtf8().c_str(), buffer);
			return;
		}
		pFileData += cnt;

		if (strcmp(texType, "png") != 0)
		{
			debug(LOG_ERROR, "%s: Only png normal maps supported", filename.toUtf8().c_str());
			return;
		}
		sstrcat(normalfile, ".png");

		/* Now read in LEVELS directive */
		if (sscanf(pFileData, "%255s %d%n", buffer, &nlevels, &cnt) != 2)
		{
			debug(LOG_ERROR, "%s: Bad levels info: %s", filename.toUtf8().c_str(), buffer);
			return;
		}
		pFileData += cnt;
	}

	if (strncmp(buffer, "SPECULARMAP", 11) == 0)
	{
		char ch, texType[PATH_MAX];
		int i;

		/* the first parameter for textures is always ignored; which is why we ignore nlevels read in above */
		ch = *pFileData++;

		// Run up to the dot or till the buffer is filled. Leave room for the extension.
		for (i = 0; i < PATH_MAX - 5 && (ch = *pFileData++) != '\0' && ch != '.'; ++i)
		{
			specfile[i] = ch;
		}
		specfile[i] = '\0';

		if (sscanf(pFileData, "%255s%n", texType, &cnt) != 1)
		{
			debug(LOG_ERROR, "%s specular map info corrupt: %s", filename.toUtf8().c_str(), buffer);
			return;
		}
		pFileData += cnt;

		if (strcmp(texType, "png") != 0)
		{
			debug(LOG_ERROR, "%s: only png specular maps supported", filename.toUtf8().c_str());
			return;
		}
		sstrcat(specfile, ".png");

		/* Try -again- to read in LEVELS directive */
		if (sscanf(pFileData, "%255s %d%n", buffer, &nlevels, &cnt) != 2)
		{
			debug(LOG_ERROR, "%s: Bad levels info: %s", filename.toUtf8().c_str(), buffer);
			return;
		}
		pFileData += cnt;
	}

	for (int i = 0; i < ANIM_EVENT_COUNT; i++)
	{
		objanimpie[i] = nullptr;
	}
	while (strncmp(buffer, "EVENT", 5) == 0)
	{
		char animpie[PATH_MAX];

		ASSERT(nlevels < ANIM_EVENT_COUNT && nlevels >= 0, "Invalid event type %d", nlevels);
		pFileData++;
		if (sscanf(pFileData, "%255s%n", animpie, &cnt) != 1)
		{
			debug(LOG_ERROR, "%s animation model corrupt: %s", filename.toUtf8().c_str(), buffer);
			return;
		}
		pFileData += cnt;

		objanimpie[nlevels] = modelGet(animpie);

		/* Try -yet again- to read in LEVELS directive */
		if (sscanf(pFileData, "%255s %d%n", buffer, &nlevels, &cnt) != 2)
		{
			debug(LOG_ERROR, "%s: Bad levels info: %s", filename.toUtf8().c_str(), buffer);
			return;
		}
		pFileData += cnt;
	}

	if (strncmp(buffer, "LEVELS", 6) != 0)
	{
		debug(LOG_ERROR, "%s: Expecting 'LEVELS' directive (%s)", filename.toUtf8().c_str(), buffer);
		return;
	}

	/* Read first LEVEL directive */
	if (sscanf(pFileData, "%255s %u%n", buffer, &level, &cnt) != 2)
	{
		debug(LOG_ERROR, "(_load_level) file corrupt -J");
		return;
	}
	pFileData += cnt;
	level--; // make zero indexed

	if (strncmp(buffer, "LEVEL", 5) != 0)
	{
		debug(LOG_ERROR, "%s: Expecting 'LEVEL' directive (%s)", filename.toUtf8().c_str(), buffer);
		return;
	}

	iIMDShape *shape = _imd_load_level(filename, &pFileData, FileDataEnd, nlevels, imd_version, level);
	if (shape == nullptr)
	{
		debug(LOG_ERROR, "%s: Unsuccessful", filename.toUtf8().c_str());
		return;
	}

	// load texture page if specified
	if (bTextured)
	{
		optional<size_t> texpage = iV_GetTexture(texfile);
		optional<size_t> normalpage;
		optional<size_t> specpage;

		ASSERT_OR_RETURN(, texpage.has_value(), "%s could not load tex page %s", filename.toUtf8().c_str(), texfile);

		if (normalfile[0] != '\0')
		{
			debug(LOG_TEXTURE, "Loading normal map %s for %s", normalfile, filename.toUtf8().c_str());
			normalpage = iV_GetTexture(normalfile, false);
			ASSERT_OR_RETURN(, normalpage.has_value(), "%s could not load tex page %s", filename.toUtf8().c_str(), normalfile);
		}

		if (specfile[0] != '\0')
		{
			debug(LOG_TEXTURE, "Loading specular map %s for %s", specfile, filename.toUtf8().c_str());
			specpage = iV_GetTexture(specfile, false);
			ASSERT_OR_RETURN(, specpage.has_value(), "%s could not load tex page %s", filename.toUtf8().c_str(), specfile);
		}

		// assign tex pages and flags to all levels
		for (iIMDShape *psShape = shape; psShape != nullptr; psShape = psShape->next)
		{
			psShape->texpage = texpage.value();
			psShape->normalpage = (normalpage.has_value()) ? normalpage.value() : iV_TEX_INVALID;
			psShape->specularpage = (specpage.has_value()) ? specpage.value() : iV_TEX_INVALID;
			psShape->flags = imd_flags;
			psShape->interpolate = (readInterpolate) ? interpolate : 1;
		}

		// check if model should use team colour mask
		if (imd_flags & iV_IMD_TCMASK)
		{
			std::string tcmask_name = pie_MakeTexPageTCMaskName(texfile);
			tcmask_name += ".png";
			optional<size_t> texpage_mask = iV_GetTexture(tcmask_name.c_str());

			ASSERT_OR_RETURN(, texpage_mask.has_value(), "%s could not load tcmask %s", filename.toUtf8().c_str(), tcmask_name.c_str());

			// Propagate settings through levels
			for (iIMDShape *psShape = shape; psShape != nullptr; psShape = psShape->next)
			{
				psShape->tcmaskpage = (texpage_mask.has_value()) ? texpage_mask.value() : iV_TEX_INVALID;
			}
		}
	}

	// copy over model-wide animation information, stored only in the first level
	for (int i = 0; i < ANIM_EVENT_COUNT; i++)
	{
		shape->objanimpie[i] = objanimpie[i];
	}

	*ppFileData = pFileData;
}