Implement animation info extraction form glTF JSON

This commit is contained in:
Camden Dixie O'Brien committed 2025-10-02 03:59:17 +01:00
1 parent 7243b51149
commit f24a920e66
1 file changed
+376 -72
+376 -72
View File
@@ -29,7 +29,7 @@ static_assert(
#define VERSION 2
#define MAX_STRING_SIZE 128
#define MAX_JOINT_COUNT 32
#define MAX_BONE_COUNT 32
enum {
CHUNK_TYPE_JSON = 0x4e4f534a, // "JSON"
@@ -80,10 +80,34 @@ typedef struct {
typedef struct {
uint32_t inverse_bind_matrices;
uint32_t joints[MAX_JOINT_COUNT];
uint32_t joints[MAX_BONE_COUNT];
uint32_t joint_count;
} skin_t;
typedef enum {
ANIMATION_PROPERTY_TRANSLATION,
ANIMATION_PROPERTY_ROTATION,
ANIMATION_PROPERTY_SCALE,
} animation_property_t;
typedef struct {
uint32_t sampler;
uint32_t node;
animation_property_t property;
} animation_channel_t;
typedef struct {
uint32_t times;
uint32_t values;
} animation_sampler_t;
typedef struct {
uint32_t times;
uint32_t translations;
uint32_t rotations;
uint32_t scales;
} animation_component_t;
typedef struct {
uint32_t view;
uint32_t offset;
@@ -99,6 +123,12 @@ typedef struct {
accessor_t weights;
accessor_t indices;
accessor_t inverse_bind_matrices;
struct {
accessor_t times[MAX_BONE_COUNT];
accessor_t translations[MAX_BONE_COUNT];
accessor_t rotations[MAX_BONE_COUNT];
accessor_t scales[MAX_BONE_COUNT];
} animation;
} accessors_t;
typedef struct {
@@ -114,6 +144,12 @@ typedef struct {
view_t weights;
view_t indices;
view_t inverse_bind_matrices;
struct {
view_t times[MAX_BONE_COUNT];
view_t translations[MAX_BONE_COUNT];
view_t rotations[MAX_BONE_COUNT];
view_t scales[MAX_BONE_COUNT];
} animation;
} views_t;
typedef struct {
@@ -129,6 +165,13 @@ typedef struct {
gltf_info_member_t weights;
gltf_info_member_t indices;
gltf_info_member_t inverse_bind_matrices;
struct {
gltf_info_member_t times[MAX_BONE_COUNT];
gltf_info_member_t translations[MAX_BONE_COUNT];
gltf_info_member_t rotations[MAX_BONE_COUNT];
gltf_info_member_t scales[MAX_BONE_COUNT];
size_t keyframe_count;
} animation;
size_t vertex_count, index_count, bone_count;
} gltf_info_t;
@@ -426,7 +469,7 @@ static skin_t read_skins(const uint8_t *p)
assert(*p == '[');
++p;
for (skin.joint_count = 0; *p != ']'; ++skin.joint_count) {
assert(skin.joint_count < MAX_JOINT_COUNT);
assert(skin.joint_count < MAX_BONE_COUNT);
skin.joints[skin.joint_count] = read_uint(&p);
if (*p == ',')
@@ -447,7 +490,7 @@ static skin_t read_skins(const uint8_t *p)
}
static void read_joint_children(
const uint8_t **p, skin_t skin, bone_t bones[MAX_JOINT_COUNT],
const uint8_t **p, skin_t skin, bone_t bones[MAX_BONE_COUNT],
uint32_t parent)
{
assert(**p == '[');
@@ -473,7 +516,7 @@ static void read_joint_children(
}
static void
read_joints(const uint8_t *p, skin_t skin, bone_t bones[MAX_JOINT_COUNT])
read_joints(const uint8_t *p, skin_t skin, bone_t bones[MAX_BONE_COUNT])
{
char buffer[MAX_STRING_SIZE];
@@ -525,6 +568,209 @@ read_joints(const uint8_t *p, skin_t skin, bone_t bones[MAX_JOINT_COUNT])
}
}
static animation_property_t read_animation_property(const uint8_t **p)
{
char buffer[MAX_STRING_SIZE];
read_string(p, buffer);
if (strcmp("translation", buffer) == 0)
return ANIMATION_PROPERTY_TRANSLATION;
else if (strcmp("rotation", buffer) == 0)
return ANIMATION_PROPERTY_ROTATION;
else if (strcmp("scale", buffer) == 0)
return ANIMATION_PROPERTY_SCALE;
else
assert(false);
}
static size_t read_animation_channels(
const uint8_t *p, animation_channel_t channels[3 * MAX_BONE_COUNT])
{
char buffer[MAX_STRING_SIZE];
assert(*p == '[');
++p;
size_t i;
for (i = 0; *p != ']'; ++i) {
assert(i < 3 * MAX_BONE_COUNT);
bool sampler = false;
bool node = false;
bool property = false;
assert(*p == '{');
++p;
while (*p != '}') {
read_string(&p, buffer);
assert(*p == ':');
++p;
if (strcmp("sampler", buffer) == 0) {
channels[i].sampler = read_uint(&p);
sampler = true;
} else if (strcmp("target", buffer) == 0) {
assert(*p == '{');
++p;
while (*p != '}') {
read_string(&p, buffer);
assert(*p == ':');
++p;
if (strcmp("node", buffer) == 0) {
channels[i].node = read_uint(&p);
node = true;
} else if (strcmp("path", buffer) == 0) {
channels[i].property = read_animation_property(&p);
property = true;
} else {
skip_value(&p);
}
if (*p == ',')
++p;
}
++p;
} else {
skip_value(&p);
}
if (*p == ',')
++p;
}
++p;
assert(sampler);
assert(node);
assert(property);
if (*p == ',')
++p;
}
return i;
}
static size_t read_animation_samplers(
const uint8_t *p, animation_sampler_t samplers[3 * MAX_BONE_COUNT])
{
char buffer[MAX_STRING_SIZE];
assert(*p == '[');
++p;
size_t i;
for (i = 0; *p != ']'; ++i) {
assert(i < 3 * MAX_BONE_COUNT);
bool times = false;
bool values = false;
assert(*p == '{');
++p;
while (*p != '}') {
read_string(&p, buffer);
assert(*p == ':');
++p;
if (strcmp("input", buffer) == 0) {
samplers[i].times = read_uint(&p);
times = true;
} else if (strcmp("output", buffer) == 0) {
samplers[i].values = read_uint(&p);
values = true;
} else if (strcmp("interpolation", buffer) == 0) {
read_string(&p, buffer);
assert(strcmp("LINEAR", buffer) == 0);
} else {
skip_value(&p);
}
if (*p == ',')
++p;
}
++p;
assert(times);
assert(values);
if (*p == ',')
++p;
}
return i;
}
static void read_animations(
const uint8_t *p, skin_t skin, animation_component_t *animation)
{
char buffer[MAX_STRING_SIZE];
animation_channel_t channels[3 * MAX_BONE_COUNT];
animation_sampler_t samplers[3 * MAX_BONE_COUNT];
assert(*p == '[');
++p;
assert(*p == '{');
++p;
const uint8_t *channels_json = nullptr;
const uint8_t *samplers_json = nullptr;
while (*p != '}') {
read_string(&p, buffer);
assert(*p == ':');
++p;
if (strcmp("channels", buffer) == 0)
channels_json = p;
else if (strcmp("samplers", buffer) == 0)
samplers_json = p;
skip_value(&p);
if (*p == ',')
++p;
}
++p;
assert(*p == ']'); // Only support one animation for now
assert(channels_json != nullptr);
assert(samplers_json != nullptr);
const size_t channel_count
= read_animation_channels(channels_json, channels);
const size_t sampler_count
= read_animation_samplers(samplers_json, samplers);
for (uint32_t i = 0; i < skin.joint_count; ++i) {
// Initialise animation component with sentinel values
animation[i].times = UINT32_MAX;
animation[i].translations = UINT32_MAX;
animation[i].rotations = UINT32_MAX;
animation[i].scales = UINT32_MAX;
for (uint32_t j = 0; j < channel_count; ++j) {
if (channels[j].node != skin.joints[i])
continue;
assert(channels[j].sampler < sampler_count);
const animation_sampler_t *sampler
= samplers + channels[j].sampler;
if (animation[i].times == UINT32_MAX)
animation[i].times = sampler->times;
else
assert(animation[i].times == sampler->times);
switch (channels[j].property) {
case ANIMATION_PROPERTY_TRANSLATION:
animation[i].translations = sampler->values;
break;
case ANIMATION_PROPERTY_ROTATION:
animation[i].rotations = sampler->values;
break;
case ANIMATION_PROPERTY_SCALE:
animation[i].scales = sampler->values;
break;
default:
assert(false);
}
}
}
}
static component_type_t read_component_type(const uint8_t **p)
{
const uint32_t component = read_uint(p);
@@ -539,10 +785,14 @@ static accessor_type_t read_accessor_type(const uint8_t **p)
read_string(p, buffer);
if (strcmp("SCALAR", buffer) == 0)
return ACCESSOR_TYPE_SCALAR;
else if (strcmp("VEC2", buffer) == 0)
return ACCESSOR_TYPE_VEC2;
else if (strcmp("VEC3", buffer) == 0)
return ACCESSOR_TYPE_VEC3;
else if (strcmp("VEC4", buffer) == 0)
return ACCESSOR_TYPE_VEC4;
else if (strcmp("MAT3", buffer) == 0)
return ACCESSOR_TYPE_MAT3;
else if (strcmp("MAT4", buffer) == 0)
return ACCESSOR_TYPE_MAT4;
else
@@ -585,36 +835,44 @@ static accessor_t read_accessor(const uint8_t **p)
return accessor;
}
static accessors_t read_accessors(const uint8_t *p, mesh_t mesh, skin_t skin)
static accessors_t read_accessors(
const uint8_t *p, mesh_t mesh, skin_t skin,
const animation_component_t *animation)
{
accessors_t accessors = {};
assert(*p == '[');
++p;
for (uint32_t i = 0; *p != ']'; ++i) {
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 if (i == skin.inverse_bind_matrices)
accessors.inverse_bind_matrices = read_accessor(&p);
else
skip_value(&p);
const accessor_t accessor = read_accessor(&p);
if (*p == ',')
++p;
if (i == mesh.normals) {
accessors.normals = accessor;
} else if (i == mesh.positions) {
accessors.positions = accessor;
} else if (i == mesh.bone_indices) {
accessors.bone_indices = accessor;
} else if (i == mesh.weights) {
accessors.weights = accessor;
} else if (i == mesh.indices) {
accessors.indices = accessor;
} else if (i == skin.inverse_bind_matrices) {
accessors.inverse_bind_matrices = accessor;
} else {
for (uint32_t j = 0; j < skin.joint_count; ++j) {
if (i == animation[j].times)
accessors.animation.times[j] = accessor;
else if (i == animation[j].translations)
accessors.animation.translations[j] = accessor;
else if (i == animation[j].rotations)
accessors.animation.rotations[j] = accessor;
else if (i == animation[j].scales)
accessors.animation.scales[j] = accessor;
}
}
}
assert(accessors.normals.count != 0);
assert(accessors.positions.count != 0);
assert(accessors.bone_indices.count != 0);
assert(accessors.weights.count != 0);
assert(accessors.indices.count != 0);
assert(accessors.inverse_bind_matrices.count != 0);
return accessors;
}
@@ -650,40 +908,44 @@ static view_t read_view(const uint8_t **p)
return view;
}
static views_t read_views(const uint8_t *p, accessors_t accessors)
static views_t
read_views(const uint8_t *p, accessors_t accessors, size_t bone_count)
{
views_t views = {};
assert(*p == '[');
++p;
for (uint32_t i = 0; *p != ']'; ++i) {
if (i == accessors.normals.view)
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 if (i == accessors.inverse_bind_matrices.view)
views.inverse_bind_matrices = read_view(&p);
else
skip_value(&p);
for (uint32_t i = 0; *p != ']'; ++i) {
const view_t view = read_view(&p);
if (*p == ',')
++p;
if (i == accessors.normals.view)
views.normals = view;
if (i == accessors.positions.view)
views.positions = view;
if (i == accessors.bone_indices.view)
views.bone_indices = view;
if (i == accessors.weights.view)
views.weights = view;
if (i == accessors.indices.view)
views.indices = view;
if (i == accessors.inverse_bind_matrices.view)
views.inverse_bind_matrices = view;
for (uint32_t j = 0; j < bone_count; ++j) {
if (i == accessors.animation.times[j].view)
views.animation.times[j] = view;
else if (i == accessors.animation.translations[j].view)
views.animation.translations[j] = view;
else if (i == accessors.animation.rotations[j].view)
views.animation.rotations[j] = view;
else if (i == accessors.animation.scales[j].view)
views.animation.scales[j] = view;
}
}
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);
assert(views.inverse_bind_matrices.len != 0);
return views;
}
@@ -713,6 +975,7 @@ static gltf_info_t read_json(const uint8_t *json)
const uint8_t *meshes_json = nullptr;
const uint8_t *skins_json = nullptr;
const uint8_t *nodes_json = nullptr;
const uint8_t *animations_json = nullptr;
const uint8_t *accessors_json = nullptr;
const uint8_t *views_json = nullptr;
while (*json != '}') {
@@ -725,6 +988,8 @@ static gltf_info_t read_json(const uint8_t *json)
skins_json = json;
else if (strcmp("nodes", buffer) == 0)
nodes_json = json;
else if (strcmp("animations", buffer) == 0)
animations_json = json;
else if (strcmp("accessors", buffer) == 0)
accessors_json = json;
else if (strcmp("bufferViews", buffer) == 0)
@@ -736,37 +1001,54 @@ static gltf_info_t read_json(const uint8_t *json)
assert(meshes_json != nullptr);
assert(skins_json != nullptr);
assert(nodes_json != nullptr);
assert(animations_json != nullptr);
assert(accessors_json != nullptr);
assert(views_json != nullptr);
const mesh_t mesh = read_meshes(meshes_json);
const skin_t skin = read_skins(skins_json);
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, skin);
const views_t views = read_views(views_json, accessors);
animation_component_t animation[MAX_BONE_COUNT];
read_animations(animations_json, skin, animation);
const accessors_t accessors
= read_accessors(accessors_json, mesh, skin, animation);
const views_t views
= read_views(views_json, accessors, skin.joint_count);
// 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);
assert(
accessors.inverse_bind_matrices.component == COMPONENT_TYPE_F32
&& accessors.inverse_bind_matrices.type == ACCESSOR_TYPE_MAT4);
assert(accessors.normals.component == COMPONENT_TYPE_F32);
assert(accessors.normals.type == ACCESSOR_TYPE_VEC3);
assert(accessors.positions.component == COMPONENT_TYPE_F32);
assert(accessors.positions.type == ACCESSOR_TYPE_VEC3);
assert(accessors.bone_indices.component == COMPONENT_TYPE_U16);
assert(accessors.bone_indices.type == ACCESSOR_TYPE_VEC4);
assert(accessors.weights.component == COMPONENT_TYPE_F32);
assert(accessors.weights.type == ACCESSOR_TYPE_VEC4);
assert(accessors.indices.component == COMPONENT_TYPE_U16);
assert(accessors.indices.type == ACCESSOR_TYPE_SCALAR);
assert(accessors.inverse_bind_matrices.component == COMPONENT_TYPE_F32);
assert(accessors.inverse_bind_matrices.type == ACCESSOR_TYPE_MAT4);
for (unsigned i = 0; i < skin.joint_count; ++i) {
assert(accessors.animation.times[i].component == COMPONENT_TYPE_F32);
assert(accessors.animation.times[i].type == ACCESSOR_TYPE_SCALAR);
assert(
accessors.animation.translations[i].component
== COMPONENT_TYPE_F32);
assert(
accessors.animation.translations[i].type == ACCESSOR_TYPE_VEC3);
assert(
accessors.animation.rotations[i].component
== COMPONENT_TYPE_F32);
assert(accessors.animation.rotations[i].type == ACCESSOR_TYPE_VEC4);
assert(
accessors.animation.scales[i].component == COMPONENT_TYPE_F32);
assert(accessors.animation.scales[i].type == ACCESSOR_TYPE_VEC3);
}
// Ensure the vertex count is consistent
assert(
@@ -777,7 +1059,16 @@ static gltf_info_t read_json(const uint8_t *json)
// Ensure the joint count is consistent
assert(accessors.inverse_bind_matrices.count == skin.joint_count);
return (gltf_info_t) {
// Ensure keyframe count is consistent
const size_t keyframe_count = accessors.animation.times[0].count;
for (unsigned i = 0; i < skin.joint_count; ++i) {
assert(accessors.animation.times[i].count == keyframe_count);
assert(accessors.animation.translations[i].count == keyframe_count);
assert(accessors.animation.rotations[i].count == keyframe_count);
assert(accessors.animation.scales[i].count == keyframe_count);
}
gltf_info_t info = {
.bones = bones,
.positions = info_member(accessors.positions, views.positions),
.normals = info_member(accessors.normals, views.normals),
@@ -790,7 +1081,20 @@ static gltf_info_t read_json(const uint8_t *json)
.inverse_bind_matrices = info_member(
accessors.inverse_bind_matrices, views.inverse_bind_matrices),
.bone_count = skin.joint_count,
.animation = { .keyframe_count = keyframe_count },
};
for (unsigned i = 0; i < info.bone_count; ++i) {
info.animation.times[i] = info_member(
accessors.animation.times[i], views.animation.times[i]);
info.animation.translations[i] = info_member(
accessors.animation.translations[i],
views.animation.translations[i]);
info.animation.rotations[i] = info_member(
accessors.animation.rotations[i], views.animation.rotations[i]);
info.animation.scales[i] = info_member(
accessors.animation.scales[i], views.animation.scales[i]);
}
return info;
}
static void load_vertices(