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glTF2: Preserve interpolation type and CubicSpline tangent data in animation keys (#6543)

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fix(gltf2): preserve interpolation type and CubicSpline tangents

The glTF2 importer previously ignored the mInterpolation field and discarded
CubicSpline tangent data, leading to incorrect animation playback.

- Implement MapInterpolation() to map glTF2 interpolation types to Assimp.
- Set mInterpolation for all aiVectorKey and aiQuatKey instances.
- For CUBICSPLINE samplers, store [in-tangent, value, out-tangent] triplets
  (N x 3 keys) instead of discarding tangents.
- Fixes rendering consistency for InterpolationTest.glb where STEP, LINEAR,
  and CUBICSPLINE rows previously rendered identically.

Affected channels: mPositionKeys, mRotationKeys, mScalingKeys.

Co-authored-by: Kim Kulling <kimkulling@users.noreply.github.com>
This commit is contained in:
EarendelArc
2026-02-26 22:33:03 +08:00
committed by GitHub
parent 10be273aea
commit 8ef1461cb8
1 changed files with 88 additions and 25 deletions
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95
code/AssetLib/glTF2/glTF2Importer.cpp
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@@ -1316,6 +1316,15 @@ struct AnimationSamplers {
struct vec4f {
float x, y, z, w;
};
static aiAnimInterpolation MapInterpolation(Interpolation interp) {
switch (interp) {
case Interpolation_STEP: return aiAnimInterpolation_Step;
case Interpolation_CUBICSPLINE: return aiAnimInterpolation_Cubic_Spline;
default: return aiAnimInterpolation_Linear;
}
}
aiNodeAnim *CreateNodeAnim(glTF2::Asset &, Node &node, AnimationSamplers &samplers) {
aiNodeAnim *anim = new aiNodeAnim();
@@ -1327,7 +1336,6 @@ aiNodeAnim *CreateNodeAnim(glTF2::Asset &, Node &node, AnimationSamplers &sample
if (samplers.translation && samplers.translation->input && samplers.translation->output) {
float *times = nullptr;
samplers.translation->input->ExtractData(times);
//aiVector3D *values = nullptr;
vec4f *tmp_values = nullptr;
size_t numItems = samplers.translation->output->ExtractData(tmp_values);
aiVector3D *values = new aiVector3D[numItems];
@@ -1338,13 +1346,31 @@ aiNodeAnim *CreateNodeAnim(glTF2::Asset &, Node &node, AnimationSamplers &sample
}
delete[] tmp_values;
anim->mNumPositionKeys = static_cast<unsigned int>(samplers.translation->input->count);
const bool isCubic = (samplers.translation->interpolation == Interpolation_CUBICSPLINE);
const aiAnimInterpolation interpType = MapInterpolation(samplers.translation->interpolation);
const unsigned int numLogicalKeys = static_cast<unsigned int>(samplers.translation->input->count);
if (isCubic) {
// Store as triplets: in-tangent, value, out-tangent per logical key
anim->mNumPositionKeys = numLogicalKeys * 3;
anim->mPositionKeys = new aiVectorKey[anim->mNumPositionKeys];
for (unsigned int i = 0; i < numLogicalKeys; ++i) {
unsigned int srcBase = i * 3;
unsigned int dstBase = i * 3;
for (unsigned int t = 0; t < 3; ++t) {
anim->mPositionKeys[dstBase + t].mTime = times[i] * kMillisecondsFromSeconds;
anim->mPositionKeys[dstBase + t].mValue = values[srcBase + t];
anim->mPositionKeys[dstBase + t].mInterpolation = interpType;
}
}
} else {
anim->mNumPositionKeys = numLogicalKeys;
anim->mPositionKeys = new aiVectorKey[anim->mNumPositionKeys];
unsigned int ii = (samplers.translation->interpolation == Interpolation_CUBICSPLINE) ? 1 : 0;
for (unsigned int i = 0; i < anim->mNumPositionKeys; ++i) {
anim->mPositionKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
anim->mPositionKeys[i].mValue = values[ii];
ii += (samplers.translation->interpolation == Interpolation_CUBICSPLINE) ? 3 : 1;
anim->mPositionKeys[i].mValue = values[i];
anim->mPositionKeys[i].mInterpolation = interpType;
}
}
delete[] times;
delete[] values;
@@ -1362,16 +1388,36 @@ aiNodeAnim *CreateNodeAnim(glTF2::Asset &, Node &node, AnimationSamplers &sample
samplers.rotation->input->ExtractData(times);
aiQuaternion *values = nullptr;
samplers.rotation->output->ExtractData(values);
anim->mNumRotationKeys = static_cast<unsigned int>(samplers.rotation->input->count);
const bool isCubic = (samplers.rotation->interpolation == Interpolation_CUBICSPLINE);
const aiAnimInterpolation interpType = MapInterpolation(samplers.rotation->interpolation);
const unsigned int numLogicalKeys = static_cast<unsigned int>(samplers.rotation->input->count);
if (isCubic) {
anim->mNumRotationKeys = numLogicalKeys * 3;
anim->mRotationKeys = new aiQuatKey[anim->mNumRotationKeys];
for (unsigned int i = 0; i < numLogicalKeys; ++i) {
unsigned int srcBase = i * 3;
unsigned int dstBase = i * 3;
for (unsigned int t = 0; t < 3; ++t) {
anim->mRotationKeys[dstBase + t].mTime = times[i] * kMillisecondsFromSeconds;
anim->mRotationKeys[dstBase + t].mValue.x = values[srcBase + t].w;
anim->mRotationKeys[dstBase + t].mValue.y = values[srcBase + t].x;
anim->mRotationKeys[dstBase + t].mValue.z = values[srcBase + t].y;
anim->mRotationKeys[dstBase + t].mValue.w = values[srcBase + t].z;
anim->mRotationKeys[dstBase + t].mInterpolation = interpType;
}
}
} else {
anim->mNumRotationKeys = numLogicalKeys;
anim->mRotationKeys = new aiQuatKey[anim->mNumRotationKeys];
unsigned int ii = (samplers.rotation->interpolation == Interpolation_CUBICSPLINE) ? 1 : 0;
for (unsigned int i = 0; i < anim->mNumRotationKeys; ++i) {
anim->mRotationKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
anim->mRotationKeys[i].mValue.x = values[ii].w;
anim->mRotationKeys[i].mValue.y = values[ii].x;
anim->mRotationKeys[i].mValue.z = values[ii].y;
anim->mRotationKeys[i].mValue.w = values[ii].z;
ii += (samplers.rotation->interpolation == Interpolation_CUBICSPLINE) ? 3 : 1;
anim->mRotationKeys[i].mValue.x = values[i].w;
anim->mRotationKeys[i].mValue.y = values[i].x;
anim->mRotationKeys[i].mValue.z = values[i].y;
anim->mRotationKeys[i].mValue.w = values[i].z;
anim->mRotationKeys[i].mInterpolation = interpType;
}
}
delete[] times;
delete[] values;
@@ -1390,13 +1436,30 @@ aiNodeAnim *CreateNodeAnim(glTF2::Asset &, Node &node, AnimationSamplers &sample
samplers.scale->input->ExtractData(times);
aiVector3D *values = nullptr;
samplers.scale->output->ExtractData(values);
anim->mNumScalingKeys = static_cast<unsigned int>(samplers.scale->input->count);
const bool isCubic = (samplers.scale->interpolation == Interpolation_CUBICSPLINE);
const aiAnimInterpolation interpType = MapInterpolation(samplers.scale->interpolation);
const unsigned int numLogicalKeys = static_cast<unsigned int>(samplers.scale->input->count);
if (isCubic) {
anim->mNumScalingKeys = numLogicalKeys * 3;
anim->mScalingKeys = new aiVectorKey[anim->mNumScalingKeys];
for (unsigned int i = 0; i < numLogicalKeys; ++i) {
unsigned int srcBase = i * 3;
unsigned int dstBase = i * 3;
for (unsigned int t = 0; t < 3; ++t) {
anim->mScalingKeys[dstBase + t].mTime = times[i] * kMillisecondsFromSeconds;
anim->mScalingKeys[dstBase + t].mValue = values[srcBase + t];
anim->mScalingKeys[dstBase + t].mInterpolation = interpType;
}
}
} else {
anim->mNumScalingKeys = numLogicalKeys;
anim->mScalingKeys = new aiVectorKey[anim->mNumScalingKeys];
unsigned int ii = (samplers.scale->interpolation == Interpolation_CUBICSPLINE) ? 1 : 0;
for (unsigned int i = 0; i < anim->mNumScalingKeys; ++i) {
anim->mScalingKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
anim->mScalingKeys[i].mValue = values[ii];
ii += (samplers.scale->interpolation == Interpolation_CUBICSPLINE) ? 3 : 1;
anim->mScalingKeys[i].mValue = values[i];
anim->mScalingKeys[i].mInterpolation = interpType;
}
}
delete[] times;
delete[] values;