下午好。我想实现骨骼动画。我在Blender中创建了一个简单的示例，并通过collada将其导出。
由于这是我的全部新手，因此我使用了collada 1.4.1规范并通过关键帧重新创建了网格。
然后，我尝试在变换矩阵之间进行插值以获得完整的动画。
Vector32BITF* vertices = (Vector32BITF*)calloc(CubeDAE::verticesCount, sizeof(Vector32BITF));
SceUShort16* indices = (SceUShort16*)calloc(CubeDAE::indicesCount, sizeof(SceUShort16));
for (unsigned int i = 0; i < CubeDAE::indicesCount; i++) { indices[i] = CubeDAE::indices[i][0]; }
float timer = 2.1f;
ScePspFMatrix4 bones_transform[3];
int keyframeA_i = 0;
int keyframeB_i = 0;
float lerpFact = 0.0f;
while(!done){
fps->PreUpdate();
keyframeA_i = ((int)timer) % CubeDAE::keyframesCount;
keyframeB_i = (((int)timer) + 1) % CubeDAE::keyframesCount;
lerpFact = pspFpuFrac(timer);
// keyframeA_i = 0;
// keyframeB_i = 1;
// lerpFact = 0.8;
for (unsigned int bone_i = 0; bone_i < CubeDAE::bonesCount; bone_i++) {
ScePspFMatrix4* local_matrixA = &CubeDAE::bones[bone_i][keyframeA_i];
ScePspFMatrix4* local_matrixB = &CubeDAE::bones[bone_i][keyframeB_i];
ScePspFVector3 positionA;
ScePspFVector3 positionB;
Mathf::Matrix::GetPosition(&positionA, local_matrixA);
Mathf::Matrix::GetPosition(&positionB, local_matrixB);
ScePspFMatrix3 rotationA;
ScePspFMatrix3 rotationB;
Mathf::Matrix::GetRotation(&rotationA, local_matrixA);
Mathf::Matrix::GetRotation(&rotationB, local_matrixB);
ScePspFVector4 q_rotationA;
ScePspFVector4 q_rotationB;
Mathf::Matrix::ConvertToQuaternion(&q_rotationA, &rotationA);
Mathf::Matrix::ConvertToQuaternion(&q_rotationB, &rotationB);
ScePspFVector3 translation;
ScePspFVector4 quaternion;
Mathf::Vector::Lerp(&translation, &positionA, &positionB, lerpFact);
Mathf::Quaternion::Slerp(&quaternion, &q_rotationA, &q_rotationB, lerpFact);
ScePspFMatrix4 offsetMatrix;
Mathf::Matrix::fromRotationTranslation(&offsetMatrix, &quaternion, &translation);
if (bone_i == 0) {
std::memcpy(&bones_transform[bone_i], &offsetMatrix, sizeof(ScePspFMatrix4));
} else if (bone_i == 1) {
Mathf::Matrix::Multiply(&bones_transform[bone_i], &offsetMatrix, &bones_transform[bone_i - 1]);
} else if (bone_i == 2) {
Mathf::Matrix::Multiply(&bones_transform[bone_i], &offsetMatrix, &bones_transform[bone_i - 2]);
}
}
unsigned int v_i = 0;
for (unsigned int vertices_i = 0; vertices_i < CubeDAE::verticesCount; vertices_i++) {
vertices[vertices_i].color = (0xff<<24)|((int)(pspFpuAbs(pspFpuCos(vertices_i)) * 255.0f) << 16)|((int)(pspFpuAbs(pspFpuSin(vertices_i)) * 255.0f) << 8)|((int)(pspFpuAbs(vertices_i) * 255.0f));
vertices[vertices_i].x = 0;
vertices[vertices_i].y = 0;
vertices[vertices_i].z = 0;
for (unsigned int vcount_i = 0; vcount_i < CubeDAE::vcount[vertices_i]; vcount_i++, v_i += 2) {
/*
SUM += ((v * BSM) * IBMi * JMi) *JM
• n: number of joints that influence vertex v
• BSM: bind shape matrix
• IBMi: inverse bind matrix of joint i
• JMi: joint matrix of joint i
• JW: joint weight/influence of joint i on vertex v
*/
// (v * BSM)
//ScePspFVector3 out = {0,0,0};
//Mathf::Vector::Transform(&out, &CubeDAE::shapeMatrix, &CubeDAE::vertices[vertices_i]);
// IBMi * JMi
ScePspFMatrix4 skinning_matrix = {{1,0,0,0}, {0,1,0,0}, {0,0,1,0}, {0,0,0,1}};
Mathf::Matrix::Multiply(&skinning_matrix, &CubeDAE::poses[CubeDAE::v[v_i]], &bones_transform[CubeDAE::v[v_i]]);
// ((v * BSM) * IBMi * JMi)
ScePspFVector3 skin = {0,0,0};
Mathf::Vector::Transform(&skin, &skinning_matrix, &CubeDAE::vertices[vertices_i]);
// ((v * BSM) * IBMi * JMi) *JM
Mathf::Vector::Scale(&skin, CubeDAE::weights[CubeDAE::v[v_i + 1]]);
vertices[vertices_i].x += skin.x;
vertices[vertices_i].y += skin.y;
vertices[vertices_i].z += skin.z;
}
}
// TODO: render here
}
但是我在某个地方犯了一个错误，所以我得到了错误的动画。
我在哪里错了？
PS：该应用程序是在PSP平台下编写的，但其含义与在任何地方所做的都没有什么不同。完整的简单示例，您可以找到here。
答案 0 :(得分：1)
经过长时间的寻找，我终于找到了它。
主要错误在于函数 Mathf :: Matrix :: fromRotationTranslation（）
是
void fromRotationTranslation(ScePspFMatrix4* result, const ScePspFVector4* quaternion, const ScePspFVector3* translation)
{
// Quaternion math
float x = quaternion->x, y = quaternion->y, z = quaternion->z, w = quaternion->w,
x2 = x + x,
y2 = y + y,
z2 = z + z,
xx = x * x2,
xy = x * y2,
xz = x * z2,
yy = y * y2,
yz = y * z2,
zz = z * z2,
wx = w * x2,
wy = w * y2,
wz = w * z2;
result->x.x = 1 - (yy + zz);
result->x.y = xy + wz;
result->x.z = xz - wy;
result->x.w = 0;
result->y.x = xy - wz;
result->y.y = 1 - (xx + zz);
result->y.z = yz + wx;
result->y.w = 0;
result->z.x = xz + wy;
result->z.y = yz - wx;
result->z.z = 1 - (xx + yy);
result->z.w = 0;
result->w.x = translation->x;
result->w.y = translation->y;
result->w.z = translation->z;
result->w.w = 1;
}
我现在有
void fromRotationTranslation(ScePspFMatrix4* result, const ScePspFVector4* quaternion, const ScePspFVector3* translation)
{
// Quaternion math
float x = quaternion->x, y = quaternion->y, z = quaternion->z, w = quaternion->w,
xx = x * x,
xy = x * y,
xz = x * z,
xw = x * w,
yy = y * y,
yz = y * z,
yw = y * w,
zz = z * z,
zw = z * w;
result->x.x = 1 - 2 * ( yy + zz );
result->x.y = 2 * ( xy - zw );
result->x.z = 2 * ( xz + yw );
result->y.x = 2 * ( xy + zw );
result->y.y = 1 - 2 * ( xx + zz );
result->y.z = 2 * ( yz - xw );
result->z.x = 2 * ( xz - yw );
result->z.y = 2 * ( yz + xw );
result->z.z = 1 - 2 * ( xx + yy );
result->x.w = translation->x;
result->y.w = translation->y;
result->z.w = translation->z;
result->w.x = result->w.y = result->w.z = 0;
result->w.w = 1;
}
PS：this FAQ
很有帮助