From 7f5d38aaf8cf7a067d1dce677b33f8b597f6a974 Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Mon, 19 Sep 2022 10:37:38 -0500
Subject: add tangents & bitangents

---
 src/import/import.c      | 68 +++++++++++++++++++++++++++++++++++++----
 src/import/import.test.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 141 insertions(+), 6 deletions(-)

diff --git a/src/import/import.c b/src/import/import.c
index a68ac05..73075d4 100644
--- a/src/import/import.c
+++ b/src/import/import.c
@@ -33,20 +33,47 @@ void push_aistring(lua_State *L, struct aiString str)
 }
 
 
+/* mesh components:
+ * DONE:
+ * mBitangents
+ * mFaces
+ * mNormals
+ * mNumFaces
+ * mNumVertices
+ * mTangents
+ * mVertices
+ *
+ * TODO:
+ * mAnimMeshes
+ * mBones
+ * mColors
+ * mMaterialIndex
+ * mMethod
+ * mName
+ * mNumAnimMeshes
+ * mNumBones
+ * mNumUVComponents
+ * mPrimitiveTypes
+ * mTextureCoords
+ * mTextureCoordsNames
+ */
 void push_mesh(lua_State *L, struct aiMesh mesh)
 {
-	/* create mesh table */
+	/* --=== create mesh table ===-- */
 	lua_createtable(L, 0, 1);
 	int meshtbl = lua_gettop(L);
 
 	int count = mesh.mNumVertices;
 	int pop_count = 0;
 
-	/* create tables */
+	/* --=== create tables ===-- */
+
+	/* positions */
 	lua_createtable(L, count, 0);
 	int vertices = lua_gettop(L);
 	pop_count += 1;
 
+	/* normals */
 	int normals = 0;
 	if (mesh.mNormals != NULL) {
 		lua_createtable(L, count, 0);
@@ -54,7 +81,19 @@ void push_mesh(lua_State *L, struct aiMesh mesh)
 		pop_count += 1;
 	}
 
-	/* populate vertices */
+	/* tangents & bitangents */
+	int tangents = 0;
+	int bitangents = 0;
+	if (mesh.mTangents != NULL) {
+		lua_createtable(L, count, 0);
+		tangents = lua_gettop(L);
+		lua_createtable(L, count, 0);
+		bitangents = lua_gettop(L);
+		pop_count += 2;
+	}
+
+	/* --=== populate vertices ===-- */
+
 	for (int i=0; i<count; i++) {
 		/* positions */
 		push_vector(L, mesh.mVertices[i]);
@@ -65,9 +104,18 @@ void push_mesh(lua_State *L, struct aiMesh mesh)
 			push_vector(L, mesh.mNormals[i]);
 			lua_rawseti(L, normals, i+1);
 		}
+
+		/* tangents */
+		if (tangents) {
+			push_vector(L, mesh.mTangents[i]);
+			lua_rawseti(L, tangents, i+1);
+			push_vector(L, mesh.mBitangents[i]);
+			lua_rawseti(L, bitangents, i+1);
+		}
 	}
 
-	/* populate faces */
+	/* --=== populate faces ===-- */
+
 	int faces = 0;
 	if (mesh.mNumFaces != 0) {
 		lua_createtable(L, mesh.mNumFaces, 0);
@@ -79,7 +127,8 @@ void push_mesh(lua_State *L, struct aiMesh mesh)
 		}
 	}
 
-	/* assign values */
+	/* --=== assign values ===-- */
+
 	lua_pushvalue(L, vertices);
 	lua_setfield(L, meshtbl, "vertices");
 
@@ -88,11 +137,18 @@ void push_mesh(lua_State *L, struct aiMesh mesh)
 		lua_setfield(L, meshtbl, "normals");
 	}
 
+	if (tangents) {
+		lua_pushvalue(L, tangents);
+		lua_setfield(L, meshtbl, "tangents");
+		lua_pushvalue(L, bitangents);
+		lua_setfield(L, meshtbl, "bitangents");
+	}
+
 	if (faces) {
 		lua_pushvalue(L, faces);
 		lua_setfield(L, meshtbl, "faces");
 	}
 
-	/* clean up */
+	/* --=== clean up ===-- */
 	lua_pop(L, pop_count);
 }
diff --git a/src/import/import.test.c b/src/import/import.test.c
index 4daaaf5..e17a685 100644
--- a/src/import/import.test.c
+++ b/src/import/import.test.c
@@ -53,6 +53,7 @@ void test_push_face()
 	int facetbl = lua_gettop(L);
 	lily_assert_int_equal(lua_objlen(L, facetbl), 6);
 
+	/* the numbers should be one higher because of lua's 1-indexing */
 	lua_rawgeti(L, facetbl, 1);
 	lily_assert_int_equal(lua_tointeger(L, -1), 1);
 	lua_rawgeti(L, facetbl, 2);
@@ -97,6 +98,9 @@ void test_faces(lua_State *L, int meshtbl);
 void create_normals(struct aiMesh *mesh);
 void test_normals(lua_State *L, int meshtbl);
 
+void create_tangents(struct aiMesh *mesh);
+void test_tangents(lua_State *L, int meshtbl);
+
 void test_nil(lua_State *L, int meshtbl, const char *field);
 
 
@@ -109,6 +113,10 @@ void test_nil(lua_State *L, int meshtbl, const char *field);
 	mesh.mVertices = vertices; \
 	struct aiVector3D normals[NUM_MESH_VERTICES]; \
 	mesh.mNormals = normals; \
+	struct aiVector3D tangents[NUM_MESH_VERTICES]; \
+	struct aiVector3D bitangents[NUM_MESH_VERTICES]; \
+	mesh.mTangents = tangents; \
+	mesh.mBitangents = bitangents; \
 	struct aiFace faces[NUM_MESH_FACES]; \
 	unsigned int index_array[3*NUM_MESH_FACES]; \
 	for (int i=0; i<NUM_MESH_FACES; i++) \
@@ -127,6 +135,8 @@ void test_push_mesh()
 	/* allocate memory */
 	ALLOCATE_MEMORY();
 	mesh.mNormals = NULL;
+	mesh.mTangents = NULL;
+	mesh.mBitangents = NULL;
 
 	/* setup mesh */
 	create_vertices(&mesh);
@@ -156,6 +166,8 @@ void test_push_mesh_faces()
 	/* allocate memory */
 	ALLOCATE_MEMORY();
 	mesh.mNormals = NULL;
+	mesh.mTangents = NULL;
+	mesh.mBitangents = NULL;
 
 	/* setup mesh */
 	create_vertices(&mesh);
@@ -185,6 +197,8 @@ void test_push_mesh_normals()
 
 	/* allocate memory */
 	ALLOCATE_MEMORY();
+	mesh.mTangents = NULL;
+	mesh.mBitangents = NULL;
 
 	/* setup mesh */
 	create_vertices(&mesh);
@@ -207,6 +221,40 @@ void test_push_mesh_normals()
 }
 
 
+void test_push_mesh_tangents()
+{
+	lua_State *L = luaL_newstate();
+	struct aiMesh mesh;
+	mesh.mNumVertices = NUM_MESH_VERTICES;
+	mesh.mNumFaces = NUM_MESH_FACES;
+
+	/* allocate memory */
+	ALLOCATE_MEMORY();
+
+	/* setup mesh */
+	create_vertices(&mesh);
+	create_faces(&mesh);
+	create_normals(&mesh);
+	create_tangents(&mesh);
+
+	/* push */	
+	int top_before = lua_gettop(L);
+	push_mesh(L, mesh);
+	int meshtbl = lua_gettop(L);
+
+	/* check output */
+	lily_assert_int_equal(lua_type(L, meshtbl), LUA_TTABLE);
+	lily_assert_int_equal(meshtbl - top_before, 1); /* make sure we cleaned up correctly */
+	test_vertices(L, meshtbl);
+	test_faces(L, meshtbl);
+	test_normals(L, meshtbl);
+	test_tangents(L, meshtbl);
+
+	lua_close(L);
+
+}
+
+
 void create_vertices(struct aiMesh *mesh)
 {
 	mesh->mVertices[0] = (struct aiVector3D) { 0, 0, 0 };
@@ -343,6 +391,36 @@ void test_normals(lua_State *L, int meshtbl)
 }
 
 
+void create_tangents(struct aiMesh *mesh)
+{
+	/* these tangents are not normalized -- see note in create_normals */
+	mesh->mTangents[0] = (struct aiVector3D) { 0.1, 0, 0 };
+	mesh->mTangents[1] = (struct aiVector3D) { 0.2, 0, 0 };
+	mesh->mTangents[2] = (struct aiVector3D) { 0.4, 0, 0 };
+	mesh->mTangents[3] = (struct aiVector3D) { 1.0, 0, 0 };
+
+	mesh->mBitangents[0] = (struct aiVector3D) { 0, 0, 0.1 };
+	mesh->mBitangents[1] = (struct aiVector3D) { 0, 0, 0.2 };
+	mesh->mBitangents[2] = (struct aiVector3D) { 0, 0, 0.4 };
+	mesh->mBitangents[3] = (struct aiVector3D) { 0, 0, 1.0 };
+}
+
+
+void test_tangents(lua_State *L, int meshtbl)
+{
+	check_vector(L, meshtbl, "tangents", 1, 0.1, 0, 0);
+	check_vector(L, meshtbl, "tangents", 2, 0.2, 0, 0);
+	check_vector(L, meshtbl, "tangents", 3, 0.4, 0, 0);
+	check_vector(L, meshtbl, "tangents", 4, 1.0, 0, 0);
+
+	check_vector(L, meshtbl, "bitangents", 1, 0, 0, 0.1);
+	check_vector(L, meshtbl, "bitangents", 2, 0, 0, 0.2);
+	check_vector(L, meshtbl, "bitangents", 3, 0, 0, 0.4);
+	check_vector(L, meshtbl, "bitangents", 4, 0, 0, 1.0);
+}
+
+
+
 void test_nil(lua_State *L, int meshtbl, const char *field)
 {
 	lua_getfield(L, meshtbl, field);
@@ -363,4 +441,5 @@ void suite_import()
 	lily_run_test(test_push_mesh);
 	lily_run_test(test_push_mesh_faces);
 	lily_run_test(test_push_mesh_normals);
+	lily_run_test(test_push_mesh_tangents);
 }
-- 
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