Load bones, bone indices and weights into model

linear_alg.h

@@ -1,6 +1,8 @@
 #ifndef LINEAR_ALG_H
 #define LINEAR_ALG_H
 
+#include <stdint.h>
+
 #define PI 3.14159265358979323846264
 
 typedef struct {
@@ -15,6 +17,10 @@ typedef struct {
 	vec4_t x, y, z, w;
 } mat4_t;
 
+typedef struct {
+	uint16_t x, y, z, w;
+} u16_vec4_t;
+
 // clang-format off
 #define MAT4_ID \
 	(mat4_t) { \

model.c

@@ -16,9 +16,19 @@ model_t model_init(size_t vertex_count, size_t index_count)
 
 void model_cleanup(model_t *m)
 {
+	if (m->vertices != nullptr) {
 		free(m->vertices);
-	free(m->indices);
 		m->vertices = nullptr;
+		m->vertex_count = 0;
+	}
+	if (m->indices != nullptr) {
+		free(m->indices);
 		m->indices = nullptr;
-	m->vertex_count = m->index_count = 0;
+		m->index_count = 0;
+	}
+	if (m->bones != nullptr) {
+		free(m->bones);
+		m->bones = nullptr;
+		m->bone_count = 0;
+	}
 }

model.h

@@ -11,13 +11,24 @@ typedef uint16_t index_t;
 typedef struct {
 	vec3_t position;
 	vec3_t normal;
+	u16_vec4_t bones;
+	vec4_t weights;
 } vertex_t;
 
+typedef struct {
+	uint32_t parent;
+	vec3_t translation;
+	vec4_t rotation;
+	vec3_t scale;
+} bone_t;
+
 typedef struct {
 	vertex_t *vertices;
 	index_t *indices;
+	bone_t *bones;
 	size_t vertex_count;
 	size_t index_count;
+	size_t bone_count;
 } model_t;
 
 model_t model_init(size_t vertex_count, size_t index_count);

model_format_glb.c

@@ -5,6 +5,7 @@
 #include <fcntl.h>
 #include <math.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
@@ -72,7 +73,7 @@ typedef struct {
 typedef struct {
 	uint32_t normals;
 	uint32_t positions;
-	uint32_t bones;
+	uint32_t bone_indices;
 	uint32_t weights;
 	uint32_t indices;
 } mesh_t;
@@ -83,22 +84,19 @@ typedef struct {
 	uint32_t joint_count;
 } skin_t;
 
-typedef struct {
-	uint32_t parent;
-	vec3_t translation;
-	vec4_t rotation;
-	vec3_t scale;
-} joint_t;
-
 typedef struct {
 	uint32_t view;
 	uint32_t offset;
 	uint32_t count;
+	component_type_t component;
+	accessor_type_t type;
 } accessor_t;
 
 typedef struct {
 	accessor_t normals;
 	accessor_t positions;
+	accessor_t bone_indices;
+	accessor_t weights;
 	accessor_t indices;
 } accessors_t;
 
@@ -111,6 +109,8 @@ typedef struct {
 typedef struct {
 	view_t normals;
 	view_t positions;
+	view_t bone_indices;
+	view_t weights;
 	view_t indices;
 } views_t;
 
@@ -120,9 +120,13 @@ typedef struct {
 } gltf_info_member_t;
 
 typedef struct {
+	bone_t *bones;
 	gltf_info_member_t normals;
 	gltf_info_member_t positions;
+	gltf_info_member_t bone_indices;
+	gltf_info_member_t weights;
 	gltf_info_member_t indices;
+	size_t vertex_count, index_count, bone_count;
 } gltf_info_t;
 
 static void *map_file(const char *path)
@@ -343,6 +347,10 @@ static mesh_t read_mesh_primitives(const uint8_t **p)
 					mesh.normals = read_uint(p);
 				} else if (strcmp("POSITION", buffer) == 0) {
 					mesh.positions = read_uint(p);
+				} else if (strcmp("JOINTS_0", buffer) == 0) {
+					mesh.bone_indices = read_uint(p);
+				} else if (strcmp("WEIGHTS_0", buffer) == 0) {
+					mesh.weights = read_uint(p);
 				} else {
 					skip_value(p);
 				}
@@ -436,7 +444,7 @@ static skin_t read_skins(const uint8_t *p)
 }
 
 static void read_joint_children(
-    const uint8_t **p, skin_t skin, joint_t joints[MAX_JOINT_COUNT],
+    const uint8_t **p, skin_t skin, bone_t bones[MAX_JOINT_COUNT],
     uint32_t parent)
 {
 	assert(**p == '[');
@@ -450,8 +458,8 @@ static void read_joint_children(
 				break;
 		}
 		assert(j < skin.joint_count);
-		assert(joints[j].parent == UINT32_MAX);
-		joints[j].parent = parent;
+		assert(bones[j].parent == UINT32_MAX);
+		bones[j].parent = parent;
 
 		if (**p == ',')
 			++(*p);
@@ -460,12 +468,12 @@ static void read_joint_children(
 }
 
 static void
-read_joints(const uint8_t *p, skin_t skin, joint_t joints[MAX_JOINT_COUNT])
+read_joints(const uint8_t *p, skin_t skin, bone_t bones[MAX_JOINT_COUNT])
 {
 	char buffer[MAX_STRING_SIZE];
 
 	for (uint32_t i = 0; i < skin.joint_count; ++i)
-		joints[i].parent = UINT32_MAX;
+		bones[i].parent = UINT32_MAX;
 
 	assert(*p == '[');
 	++p;
@@ -492,13 +500,13 @@ read_joints(const uint8_t *p, skin_t skin, joint_t joints[MAX_JOINT_COUNT])
 			++p;
 
 			if (strcmp("children", buffer) == 0)
-				read_joint_children(&p, skin, joints, j);
+				read_joint_children(&p, skin, bones, j);
 			else if (strcmp("translation", buffer) == 0)
-				joints[j].translation = read_vec3(&p);
+				bones[j].translation = read_vec3(&p);
 			else if (strcmp("rotation", buffer) == 0)
-				joints[j].rotation = read_vec4(&p);
+				bones[j].rotation = read_vec4(&p);
 			else if (strcmp("scale", buffer) == 0)
-				joints[j].scale = read_vec3(&p);
+				bones[j].scale = read_vec3(&p);
 			else
 				skip_value(&p);
 
@@ -512,6 +520,14 @@ read_joints(const uint8_t *p, skin_t skin, joint_t joints[MAX_JOINT_COUNT])
 	}
 }
 
+static component_type_t read_component_type(const uint8_t **p)
+{
+	const uint32_t component = read_uint(p);
+	assert(component >= COMPONENT_TYPE_S8);
+	assert(component <= COMPONENT_TYPE_F32);
+	return (component_type_t)component;
+}
+
 static accessor_type_t read_accessor_type(const uint8_t **p)
 {
 	char buffer[MAX_STRING_SIZE];
@@ -528,8 +544,7 @@ static accessor_type_t read_accessor_type(const uint8_t **p)
 		assert(false);
 }
 
-static accessor_t read_accessor(
-    const uint8_t **p, component_type_t component_type, accessor_type_t type)
+static accessor_t read_accessor(const uint8_t **p)
 {
 	char buffer[MAX_STRING_SIZE];
 	accessor_t accessor = {};
@@ -549,9 +564,9 @@ static accessor_t read_accessor(
 		else if (strcmp("count", buffer) == 0)
 			accessor.count = read_uint(p);
 		else if (strcmp("componentType", buffer) == 0)
-			assert(read_uint(p) == component_type);
+			accessor.component = read_component_type(p);
 		else if (strcmp("type", buffer) == 0)
-			assert(read_accessor_type(p) == type);
+			accessor.type = read_accessor_type(p);
 		else if (strcmp("sparse", buffer) == 0)
 			assert(false); // Sparse accessors are not supported
 		else
@@ -571,19 +586,18 @@ static accessors_t read_accessors(const uint8_t *p, mesh_t mesh)
 	assert(*p == '[');
 	++p;
 	for (uint32_t i = 0; *p != ']'; ++i) {
-		if (i == mesh.normals) {
-			accessors.normals
-			    = read_accessor(&p, COMPONENT_TYPE_F32, ACCESSOR_TYPE_VEC3);
-		} else if (i == mesh.positions) {
-			accessors.positions
-			    = read_accessor(&p, COMPONENT_TYPE_F32, ACCESSOR_TYPE_VEC3);
-		} else if (i == mesh.indices) {
-			accessors.indices = read_accessor(
-			    &p, COMPONENT_TYPE_U16, ACCESSOR_TYPE_SCALAR);
-		} else {
+		if (i == mesh.normals)
+			accessors.normals = read_accessor(&p);
+		else if (i == mesh.positions)
+			accessors.positions = read_accessor(&p);
+		else if (i == mesh.bone_indices)
+			accessors.bone_indices = read_accessor(&p);
+		else if (i == mesh.weights)
+			accessors.weights = read_accessor(&p);
+		else if (i == mesh.indices)
+			accessors.indices = read_accessor(&p);
+		else
 			skip_value(&p);
-		}
-
 		if (*p == ',')
 			++p;
 	}
@@ -632,6 +646,10 @@ static views_t read_views(const uint8_t *p, accessors_t accessors)
 			views.normals = read_view(&p);
 		else if (i == accessors.positions.view)
 			views.positions = read_view(&p);
+		else if (i == accessors.bone_indices.view)
+			views.bone_indices = read_view(&p);
+		else if (i == accessors.weights.view)
+			views.weights = read_view(&p);
 		else if (i == accessors.indices.view)
 			views.indices = read_view(&p);
 		else
@@ -643,9 +661,23 @@ static views_t read_views(const uint8_t *p, accessors_t accessors)
 
 	if (accessors.normals.view == accessors.positions.view)
 		views.positions = views.normals;
+
+	assert(views.normals.len != 0);
+	assert(views.positions.len != 0);
+	assert(views.bone_indices.len != 0);
+	assert(views.weights.len != 0);
+	assert(views.indices.len != 0);
 	return views;
 }
 
+static gltf_info_member_t info_member(accessor_t accessor, view_t view)
+{
+	return (gltf_info_member_t) {
+		.len = view.stride == 0 ? view.len : accessor.count * view.stride,
+		.offset = view.offset + accessor.offset,
+	};
+}
+
 static gltf_info_t read_json(const uint8_t *json)
 {
 	char buffer[MAX_STRING_SIZE];
@@ -692,38 +724,60 @@ static gltf_info_t read_json(const uint8_t *json)
 
 	const mesh_t mesh = read_meshes(meshes_json);
 	const skin_t skin = read_skins(skins_json);
-	joint_t joints[MAX_JOINT_COUNT] = {};
-	read_joints(nodes_json, skin, joints);
+	bone_t *bones = calloc(skin.joint_count, sizeof(bone_t));
+	assert(bones != nullptr);
+	read_joints(nodes_json, skin, bones);
 
 	const accessors_t accessors = read_accessors(accessors_json, mesh);
 	const views_t views = read_views(views_json, accessors);
 
-	// Assume indices are in their own buffer view
-	assert(views.indices.stride == 0);
+	// Verify data types
+	assert(
+	    accessors.normals.component == COMPONENT_TYPE_F32
+	    && accessors.normals.type == ACCESSOR_TYPE_VEC3);
+	assert(
+	    accessors.positions.component == COMPONENT_TYPE_F32
+	    && accessors.positions.type == ACCESSOR_TYPE_VEC3);
+	assert(
+	    accessors.bone_indices.component == COMPONENT_TYPE_U16
+	    && accessors.bone_indices.type == ACCESSOR_TYPE_VEC4);
+	assert(
+	    accessors.weights.component == COMPONENT_TYPE_F32
+	    && accessors.weights.type == ACCESSOR_TYPE_VEC4);
+	assert(
+	    accessors.indices.component == COMPONENT_TYPE_U16
+	    && accessors.indices.type == ACCESSOR_TYPE_SCALAR);
+
+	// Ensure the vertex count is consistent
+	assert(
+	    accessors.positions.count == accessors.normals.count
+	    && accessors.positions.count == accessors.bone_indices.count
+	    && accessors.positions.count == accessors.weights.count);
 
 	return (gltf_info_t) {
-		.normals = {
-			.offset = views.normals.offset + accessors.normals.offset,
-			.len = accessors.normals.count * sizeof(vec3_t),
-		},
-		.positions = {
-			.offset = views.positions.offset + accessors.positions.offset,
-			.len = accessors.positions.count * sizeof(vec3_t),
-		},
-		.indices = {
-			.offset = views.indices.offset + accessors.indices.offset,
-			.len = views.indices.len,
-		},
+		.bones = bones,
+		.positions = info_member(accessors.positions, views.positions),
+		.normals = info_member(accessors.normals, views.normals),
+		.bone_indices
+		= info_member(accessors.bone_indices, views.bone_indices),
+		.weights = info_member(accessors.weights, views.weights),
+		.indices = info_member(accessors.indices, views.indices),
+		.vertex_count = accessors.positions.count,
+		.index_count = accessors.indices.count,
+		.bone_count = skin.joint_count,
 	};
 }
 
 static void load_vertices(
     vertex_t *restrict dest, const vec3_t *restrict positions,
-    const vec3_t *restrict normals, size_t count)
+    const vec3_t *restrict normals, const u16_vec4_t *restrict bones,
+    const vec4_t *restrict weights, size_t count)
 {
 	for (unsigned i = 0; i < count; ++i) {
 		dest[i].position = positions[i];
 		dest[i].normal = normals[i];
+		dest[i].bones = bones[i];
+		dest[i].weights = weights[i];
 	}
 }
 
@@ -743,17 +797,6 @@ model_t model_format_glb_read(const char *path)
 	offset += sizeof(chunk_hdr_t);
 	const gltf_info_t info = read_json(file + offset);
 
-	// Check glTF info for validity
-	assert(info.positions.len == info.normals.len);
-	assert(info.positions.offset != info.normals.offset);
-	if (info.positions.offset < info.normals.offset) {
-		const uint32_t pos_end = info.positions.offset + info.positions.len;
-		assert(pos_end <= info.normals.offset);
-	} else {
-		const uint32_t norm_end = info.normals.offset + info.normals.len;
-		assert(norm_end <= info.positions.offset);
-	}
-
 	// Read binary chunk header
 	offset += json_hdr->len;
 	assert(offset != len);
@@ -765,13 +808,14 @@ model_t model_format_glb_read(const char *path)
 	assert(offset == len);
 
 	// Load data from binary chunk into model
-	const size_t vertex_count = info.positions.len / sizeof(vec3_t);
-	const size_t index_count = info.indices.len / sizeof(index_t);
-	model_t model = model_init(vertex_count, index_count);
-	const vec3_t *positions
-	    = (const vec3_t *)(bin_data + info.positions.offset);
-	const vec3_t *normals = (const vec3_t *)(bin_data + info.normals.offset);
-	load_vertices(model.vertices, positions, normals, vertex_count);
+	model_t model = model_init(info.vertex_count, info.index_count);
+	model.bone_count = info.bone_count;
+	model.bones = info.bones;
+	load_vertices(
+	    model.vertices, (const vec3_t *)(bin_data + info.positions.offset),
+	    (const vec3_t *)(bin_data + info.normals.offset),
+	    (const u16_vec4_t *)(bin_data + info.bone_indices.offset),
+	    (const vec4_t *)(bin_data + info.weights.offset), info.vertex_count);
 	memcpy(model.indices, bin_data + info.indices.offset, info.indices.len);
 
 	munmap(file, len);

model_format_utah.c

@@ -184,7 +184,7 @@ static vertex_t read_vertex(read_ctx_t *ctx)
 {
 	const vec3_t position = read_vec3(ctx);
 	const vec3_t normal = read_vec3(ctx);
-	return (vertex_t) { position, normal };
+	return (vertex_t) { position, normal, {}, {} };
 }
 
 model_t model_format_utah_read(const char *path)