+glm::mat4 lerpPosition(const aiNodeAnim *anim, const float tick) {
+ if (anim->mNumPositionKeys == 0) return glm::mat4(1.f);
+
+ int yIndex = -1;
+ for (int i = 0; i < anim->mNumPositionKeys; i++) {
+ aiVectorKey vk = anim->mPositionKeys[i];
+ if (vk.mTime > tick) {
+ yIndex = i;
+ break;
+ }
+ }
+ aiVector3D lerpPos;
+ if (yIndex == 0) {
+ lerpPos = anim->mPositionKeys[0].mValue;
+ } else if (yIndex == -1) {
+ lerpPos = anim->mPositionKeys[anim->mNumPositionKeys - 1].mValue;
+ } else {
+ auto X = anim->mPositionKeys[yIndex - 1];
+ auto Y = anim->mPositionKeys[yIndex];
+
+ lerpPos = (X.mValue * (float)(Y.mTime - tick) + Y.mValue * (float)(tick - X.mTime)) / (float)(Y.mTime - X.mTime);
+ }
+ aiMatrix4x4 result;
+ aiMatrix4x4::Translation(lerpPos, result);
+ return aiMatrixToMat4(result);
+}
+
+glm::mat4 lerpRotation(const aiNodeAnim *anim, const float tick) {
+ int yIndex = -1;
+ for (int i = 0; i < anim->mNumRotationKeys; i++) {
+ aiQuatKey vk = anim->mRotationKeys[i];
+ if (vk.mTime > tick) {
+ yIndex = i;
+ break;
+ }
+ }
+
+ aiQuaternion result;
+ if (yIndex < 1) {
+ result = anim->mRotationKeys[0].mValue;
+ } else if (yIndex == -1) {
+ result = anim->mRotationKeys[anim->mNumRotationKeys - 1].mValue;
+ } else {
+
+ auto X = anim->mRotationKeys[yIndex - 1];
+ auto Y = anim->mRotationKeys[yIndex];
+
+ float mix = (tick - X.mTime) / (Y.mTime - X.mTime);
+
+ aiQuaternion::Interpolate(result, X.mValue, Y.mValue, mix);
+
+ }
+ return aiMatrixToMat4(aiMatrix4x4(result.GetMatrix()));
+}
+
+glm::mat4 lerpScaling(const aiNodeAnim *anim, const float tick) {
+ int yIndex = -1;
+ for (int i = 0; i < anim->mNumScalingKeys; i++) {
+ aiVectorKey vk = anim->mScalingKeys[i];
+ if (vk.mTime > tick) {
+ yIndex = i;
+ break;
+ }
+ }
+
+ aiVector3D lerpPos;
+ if (yIndex < 1) {
+ lerpPos = anim->mScalingKeys[0].mValue;
+ } else {
+ auto X = anim->mScalingKeys[yIndex - 1];
+ auto Y = anim->mScalingKeys[yIndex];
+
+ lerpPos = (X.mValue * (float)(Y.mTime - tick) + Y.mValue * (float)(tick - X.mTime)) / (float)(Y.mTime - X.mTime);
+ }
+ aiMatrix4x4 result;
+ aiMatrix4x4::Scaling(lerpPos, result);
+ return aiMatrixToMat4(result);