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ogt_vox: implement correct wrapping of looping animations
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- all animation sampling now correctly takes into account the
  'loop' property of the animation.
- added new APIs:
  -- ogt_vox_sample_instance_model: gets the model_index for a
     given instance on a given frame.
  -- ogt_vox_sample_instance_transform: gets the flattened transform
     for a given instance on a given frame. (takes into account any
	 group transform animations)
- added internal ogt_vox_test function that is used to verify the
  new frame wrapping logic. Should probably write more directed tests
  for the internals of this lib at some point.
  • Loading branch information
@jpaver
jpaver committed Apr 22, 2022
1 parent b53d577 commit 66d3397
Showing 1 changed file with 90 additions and 7 deletions.
97 changes: 90 additions & 7 deletions src/ogt_vox.h
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Original file line number Diff line number Diff line change
Expand Up @@ -421,12 +421,18 @@
// If you require specific colors in the merged scene palette, provide up to and including 255 of them via required_colors/required_color_count.
ogt_vox_scene* ogt_vox_merge_scenes(const ogt_vox_scene** scenes, uint32_t scene_count, const ogt_vox_rgba* required_colors, const uint32_t required_color_count);

// sample which model_index the given animation produces at the given frame
// samples which model_index the given animation produces at the given frame
uint32_t ogt_vox_sample_anim_model(const ogt_vox_anim_model* anim, uint32_t frame_index);

// sample which transform the given animation produces at the given frame
// // sample which transform the given animation produces at the given frame
ogt_vox_transform ogt_vox_sample_anim_transform(const ogt_vox_anim_transform* anim, uint32_t frame_index);

// sample the model for a given instance at the given frame
uint32_t ogt_vox_sample_instance_model(const ogt_vox_instance* instance, uint32_t frame_index);

// sample the flattened transform for a given instance at the given frame (takes into account group hierarchy and group animations)
ogt_vox_transform ogt_vox_sample_instance_transform(const ogt_vox_instance* instance, uint32_t frame_index, const ogt_vox_scene* scene);

#endif // OGT_VOX_H__

//-----------------------------------------------------------------------------------------------------------------
Expand Down Expand Up @@ -1059,10 +1065,30 @@
// but they are only equal if they have exactly the same voxel data.
return memcmp(lhs->voxel_data, rhs->voxel_data, num_voxels_lhs) == 0 ? true : false;
}

static ogt_vox_transform sample_keyframe_transform(const ogt_vox_keyframe_transform* keyframes, uint32_t num_keyframes, uint32_t frame_index)

// wraps the specified frame_index such that it is inclusively between the first and last loop frames
uint32_t compute_looped_frame_index(uint32_t first_loop_frame, uint32_t last_loop_frame, uint32_t frame_index)
{
uint32_t loop_len = 1 + last_loop_frame - first_loop_frame;
uint32_t looped_frame_index;
if (frame_index >= first_loop_frame) {
uint32_t frames_since_first_frame = frame_index - first_loop_frame;
looped_frame_index = first_loop_frame + (frames_since_first_frame % loop_len);
}
else {
uint32_t frames_since_first_frame = (first_loop_frame - frame_index - 1);
looped_frame_index = last_loop_frame - (frames_since_first_frame % loop_len);
}
ogt_assert(looped_frame_index >= first_loop_frame && looped_frame_index <= last_loop_frame, "bug in looping logic!");
return looped_frame_index;
}

static ogt_vox_transform sample_keyframe_transform(const ogt_vox_keyframe_transform* keyframes, uint32_t num_keyframes, bool loop, uint32_t frame_index)
{
ogt_assert(num_keyframes >= 1, "need at least one keyframe to sample");
if (loop) {
frame_index = compute_looped_frame_index(keyframes[0].frame_index, keyframes[num_keyframes-1].frame_index, frame_index);
}
if (frame_index <= keyframes[0].frame_index)
return keyframes[0].transform;
if (frame_index >= keyframes[num_keyframes-1].frame_index)
Expand Down Expand Up @@ -1091,12 +1117,15 @@

ogt_vox_transform ogt_vox_sample_anim_transform(const ogt_vox_anim_transform* anim, uint32_t frame_index)
{
return sample_keyframe_transform(anim->keyframes, anim->num_keyframes, frame_index);
return sample_keyframe_transform(anim->keyframes, anim->num_keyframes, anim->loop, frame_index);
}

uint32_t ogt_vox_sample_anim_model(const ogt_vox_anim_model* anim, uint32_t frame_index)
{
ogt_assert(anim->num_keyframes >= 1, "need at least one keyframe to sample");
if (anim->loop) {
frame_index = compute_looped_frame_index(anim->keyframes[0].frame_index, anim->keyframes[anim->num_keyframes-1].frame_index, frame_index);
}
if (frame_index <= anim->keyframes[0].frame_index)
return anim->keyframes[0].model_index;
if (frame_index >=anim-> keyframes[anim->num_keyframes-1].frame_index)
Expand All @@ -1110,6 +1139,25 @@
return anim->keyframes[0].model_index;
}

// computes the flattened transform for an instance on a given frame (pass the scene so that group transform hierarchy can also be considered)
ogt_vox_transform ogt_vox_sample_instance_transform(const ogt_vox_instance* instance, uint32_t frame_index, const ogt_vox_scene* scene)
{
ogt_vox_transform flattened_transform = instance->transform_anim.num_keyframes ? ogt_vox_sample_anim_transform(&instance->transform_anim, frame_index) : instance->transform;
uint32_t group_index = instance->group_index;
while (group_index != k_invalid_group_index) {
const ogt_vox_group* group = &scene->groups[group_index];
ogt_vox_transform group_transform = group->transform_anim.num_keyframes ? ogt_vox_sample_anim_transform(&group->transform_anim, frame_index) : group->transform;
flattened_transform = _vox_transform_multiply(flattened_transform, group_transform);
group_index = group->parent_group_index;
}
return flattened_transform;
}

uint32_t ogt_vox_sample_instance_model(const ogt_vox_instance* instance, uint32_t frame_index)
{
return instance->model_anim.num_keyframes ? ogt_vox_sample_anim_model(&instance->model_anim, frame_index) : instance->model_index;
}

const ogt_vox_scene* ogt_vox_read_scene_with_flags(const uint8_t * buffer, uint32_t buffer_size, uint32_t read_flags) {
_vox_file file = { buffer, buffer_size, 0 };
_vox_file* fp = &file;
Expand Down Expand Up @@ -1661,12 +1709,12 @@
for (uint32_t f = 0; f < frame_indices.size(); f++) {
uint32_t frame_index = frame_indices[f];
const ogt_vox_keyframe_transform* instance_keyframes = (const ogt_vox_keyframe_transform*)&misc_data[(size_t)instance->transform_anim.keyframes];
ogt_vox_transform flattened_transform = sample_keyframe_transform(instance_keyframes, instance->transform_anim.num_keyframes, frame_index);
ogt_vox_transform flattened_transform = sample_keyframe_transform(instance_keyframes, instance->transform_anim.num_keyframes, instance->transform_anim.loop, frame_index);
uint32_t group_index = instance->group_index;
while (group_index != k_invalid_group_index) {
const ogt_vox_group* group = &groups[group_index];
const ogt_vox_keyframe_transform* group_keyframes = (const ogt_vox_keyframe_transform*)&misc_data[(size_t)group->transform_anim.keyframes];
ogt_vox_transform group_transform = sample_keyframe_transform(group_keyframes, group->transform_anim.num_keyframes, frame_index);
ogt_vox_transform group_transform = sample_keyframe_transform(group_keyframes, group->transform_anim.num_keyframes, group->transform_anim.loop, frame_index);
flattened_transform = _vox_transform_multiply(flattened_transform, group_transform);
group_index = groups[group_index].parent_group_index;
}
Expand Down Expand Up @@ -2825,6 +2873,41 @@
return merged_scene;
}

void ogt_vox_test()
{
// frame_index looping tests
{
const char* test_message = "failed compute_looped_frame_index test";
// [0,0] = 1 keyframe animation starting at frame 0
ogt_assert(compute_looped_frame_index( 0, 0, 0 ) == 0, test_message);
ogt_assert(compute_looped_frame_index( 0, 0, 1 ) == 0, test_message);
ogt_assert(compute_looped_frame_index( 0, 0, 15) == 0, test_message);
// [1,1] = 1 keyframe animation starting at frame 1
ogt_assert(compute_looped_frame_index( 1, 1, 0) == 1, test_message);
ogt_assert(compute_looped_frame_index( 1, 1, 1) == 1, test_message);
ogt_assert(compute_looped_frame_index( 1, 1, 15) == 1, test_message);
// [0,9] = 10 keyframe animation starting at frame 0
ogt_assert(compute_looped_frame_index( 0, 9, 0) == 0, test_message);
ogt_assert(compute_looped_frame_index( 0, 9, 4) == 4, test_message);
ogt_assert(compute_looped_frame_index( 0, 9, 9) == 9, test_message);
ogt_assert(compute_looped_frame_index( 0, 9, 10) == 0, test_message);
ogt_assert(compute_looped_frame_index( 0, 9, 11) == 1, test_message);
ogt_assert(compute_looped_frame_index( 0, 9, 14) == 4, test_message);
ogt_assert(compute_looped_frame_index( 0, 9, 19) == 9, test_message);
ogt_assert(compute_looped_frame_index( 0, 9, 21) == 1, test_message);
// [4,13] = 10 keyframe animation starting at frame 4
ogt_assert(compute_looped_frame_index(4, 13, 0 ) == 10, test_message);
ogt_assert(compute_looped_frame_index(4, 13, 3 ) == 13, test_message);
ogt_assert(compute_looped_frame_index(4, 13, 4 ) == 4, test_message);
ogt_assert(compute_looped_frame_index(4, 13, 5 ) == 5, test_message);
ogt_assert(compute_looped_frame_index(4, 13, 12) == 12, test_message);
ogt_assert(compute_looped_frame_index(4, 13, 13) == 13, test_message);
ogt_assert(compute_looped_frame_index(4, 13, 14) == 4, test_message);
ogt_assert(compute_looped_frame_index(4, 13, 21) == 11, test_message);
}

}

#endif // #ifdef OGT_VOX_IMPLEMENTATION

/* -------------------------------------------------------------------------------------------------------------------------------------------------
Expand Down

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