From 344f13204481d28cb7af2c8a37bfa77ee5ece6a4 Mon Sep 17 00:00:00 2001
From: Denis Pauk <pauk.denis@gmail.com>
Date: Sun, 17 Mar 2024 14:07:35 +0200
Subject: [PATCH] models: MDX mesh split by subobj value

---
 src/client/refresh/files/models.c | 121 +++++++++++++++++++++++++++---
 src/common/header/files.h         |   2 +-
 2 files changed, 111 insertions(+), 12 deletions(-)

diff --git a/src/client/refresh/files/models.c b/src/client/refresh/files/models.c
index 318ff0e4..c89c886d 100644
--- a/src/client/refresh/files/models.c
+++ b/src/client/refresh/files/models.c
@@ -284,6 +284,111 @@ Mod_LoadMD2TriangleList(dmdx_t *pheader, const dtriangle_t *pintri)
 	}
 }
 
+/*
+=================
+Mod_LoadMDXTriangleList
+
+Load MDX triangle lists
+=================
+*/
+static void
+Mod_LoadMDXTriangleList(const char *mod_name, dmdx_t *pheader, const dtriangle_t *pintri,
+	const int *glcmds, int num_glcmds)
+{
+	const dtriangle_t *pouttriofs;
+	dmdxmesh_t *mesh_nodes;
+	dtriangle_t *pouttri;
+	const int *glcmds_end;
+	dstvert_t *stvert;
+	int m, *mesh_ids;
+
+	pouttriofs = pouttri = (dtriangle_t *) ((char *)pheader + pheader->ofs_tris);
+	mesh_nodes = (dmdxmesh_t *)((char *)pheader + pheader->ofs_meshes);
+	pouttri = (dtriangle_t *) ((byte *)pheader + pheader->ofs_tris);
+	stvert = (dstvert_t *)((byte *)pheader + pheader->ofs_st);
+	mesh_ids = (int *)calloc(pheader->num_xyz, sizeof(int));
+	glcmds_end = glcmds + num_glcmds;
+
+	while (1)
+	{
+		int count, mesh_id;
+
+		/* get the vertex count and primitive type */
+		count = LittleLong(*glcmds++);
+
+		if (!count || glcmds >= glcmds_end)
+		{
+			break; /* done */
+		}
+
+		if (count < 0)
+		{
+			count = -count;
+		}
+
+		/* num meshes should be same as subobjects */
+		mesh_id = LittleLong(*glcmds++) % pheader->num_meshes;
+
+		do
+		{
+			int index_xyz;
+			vec2_t st;
+
+			memcpy(&st, glcmds, sizeof(st));
+			index_xyz = LittleLong(glcmds[2]);
+
+			mesh_ids[index_xyz] = mesh_id;
+			stvert[index_xyz].s = LittleFloat(st[0]) * pheader->skinwidth;
+			stvert[index_xyz].t = LittleFloat(st[1]) * pheader->skinheight;
+			glcmds += 3;
+		}
+		while (--count);
+	}
+
+	for (m = 0; m < pheader->num_meshes; m++)
+	{
+		int i;
+
+		mesh_nodes[m].ofs_tris = pouttri - pouttriofs;
+
+		for (i = 0; i < pheader->num_tris; i++)
+		{
+			int j, index[3];
+
+			for (j = 0; j < 3; j++)
+			{
+				index[j] = LittleShort(pintri[i].index_xyz[j]);
+			}
+
+			/* sanity check for verts */
+			if (mesh_ids[index[0]] != mesh_ids[index[1]] ||
+				mesh_ids[index[1]] != mesh_ids[index[2]])
+			{
+				R_Printf(PRINT_DEVELOPER,
+					"%s: %s: Mesh detect could be wrong (%d != %d != %d)\n",
+					__func__, mod_name,
+					mesh_ids[index[0]], mesh_ids[index[1]], mesh_ids[index[2]]);
+			}
+
+			/* use only first vert for mesh detect */
+			if (mesh_ids[LittleShort(pintri[i].index_xyz[0])] == m)
+			{
+				for (j = 0; j < 3; j++)
+				{
+					pouttri->index_xyz[j] = index[j];
+					/* ST is always zero in input */
+					pouttri->index_st[j] = index[j];
+				}
+				pouttri++;
+			}
+		}
+
+		mesh_nodes[m].num_tris = pouttri - pouttriofs - mesh_nodes[m].ofs_tris;
+	}
+
+	free(mesh_ids);
+}
+
 /*
 =================
 Mod_LoadMD2TriangleList
@@ -2333,7 +2438,6 @@ Mod_LoadModel_MDX(const char *mod_name, const void *buffer, int modfilelen,
 	dmdx_t dmdxheader, *pheader = NULL;
 	vec3_t translate = {0, 0, 0};
 	mdx_header_t header = {0};
-	dmdxmesh_t *mesh_nodes;
 	void *extradata = NULL;
 	int i;
 
@@ -2377,7 +2481,7 @@ Mod_LoadModel_MDX(const char *mod_name, const void *buffer, int modfilelen,
 	dmdxheader.framesize = sizeof(daliasxframe_t) - sizeof(dxtrivertx_t);
 	dmdxheader.framesize += header.num_xyz * sizeof(dxtrivertx_t);
 
-	dmdxheader.num_meshes = 1;
+	dmdxheader.num_meshes = header.num_subobj;
 	dmdxheader.num_skins = header.num_skins;
 	dmdxheader.num_xyz = header.num_xyz;
 	dmdxheader.num_st = header.num_xyz;
@@ -2402,19 +2506,14 @@ Mod_LoadModel_MDX(const char *mod_name, const void *buffer, int modfilelen,
 
 	memcpy(pheader, &dmdxheader, sizeof(dmdxheader));
 
-	/* create single mesh */
-	mesh_nodes = (dmdxmesh_t *)((char *)pheader + pheader->ofs_meshes);
-	mesh_nodes[0].ofs_tris = 0;
-	mesh_nodes[0].num_tris = pheader->num_tris;
-
 	memcpy((byte*)pheader + pheader->ofs_skins, (byte *)buffer + header.ofs_skins,
 		pheader->num_skins * MAX_SKINNAME);
-	Mod_LoadSTvertList(pheader,
-		(dstvert_t *)((byte *)buffer + header.ofs_st));
+	Mod_LoadMDXTriangleList(mod_name, pheader,
+		(dtriangle_t *)((byte *)buffer + header.ofs_tris),
+		(int*)((byte *)buffer + header.ofs_glcmds),
+		header.num_glcmds);
 	Mod_LoadFrames_MD2(pheader, (byte *)buffer + header.ofs_frames,
 		header.framesize, translate);
-	Mod_LoadMD2TriangleList(pheader,
-		(dtriangle_t *)((byte *)buffer + header.ofs_tris));
 	Mod_LoadCmdGenerate(pheader);
 	Mod_LoadFixImages(mod_name, pheader, false);
 
diff --git a/src/common/header/files.h b/src/common/header/files.h
index ebdf562f..938855fb 100644
--- a/src/common/header/files.h
+++ b/src/common/header/files.h
@@ -309,7 +309,7 @@ typedef struct mdx_header_s
 	int ofs_tris;          /* offset for dtriangles */
 	int ofs_frames;        /* offset for first frame */
 	int ofs_glcmds;
-	int ofs_st;
+	int ofs_verts;         /* link vert to subobj */
 	int ofs_sfxdef;
 	int ofs_sfxent;
 	int ofs_bbox;