using namespace glm;
-constexpr float tolerance = 0.3;
+constexpr float tolerance = 0.001;
const std::vector<glm::vec3> fabrik(const glm::vec3 t,
const std::vector<glm::vec3> jpsIn, // joint positions
return vec3(trans[3]);
}
-glm::mat4 absoluteToModelSpace(const Model::Node &root, const Model::Node &n, mat4 m) {
+mat4 absoluteToModelSpace(const Model::Node &root, const Model::Node &n, mat4 m) {
const Model::Node *parent = &n;
glm::mat4 res = m;
std::vector<mat4> trans;
return res;
}
+// Normalizes a transformation matrix to not have any scale factor
+inline mat4 normalizeScale(mat4 m) {
+ for (int i = 0; i < 3; i++)
+ m[i] = normalize(m[i]);
+ return m;
+}
-void inverseKinematic(Model::Node &root, Model::Node &end, vec3 target) {
- /* float s2o2 = sqrt(2.f) / 2.f; */
- /* assert(getRotationToPoint({1, 0, 0}, {0, s2o2, s2o2}, 1) */
- /* == mat4({0, s2o2, s2o2, 0}, { -s2o2, 1.f/2.f, -1.f/2.f, 0}, */
- /* {-s2o2, -1.f/2.f, 1.f/2.f, 0}, { 0, 0, 0, 1})); */
+float d = 0;
- std::vector<Model::Node> chain = allNodesTo(root, end);
+// Target is world position
+void inverseKinematics(Model::Node &start, Model::Node &end, vec3 target) {
+ std::vector<Model::Node> chain = allNodesTo(start, end);
assert(!chain.empty());
+ // Calculate the world root
+ const Model::Node &root = start.getRoot();
+
+ // Work out the positions and distances
std::vector<vec3> positions(chain.size()); std::vector<float> distances(chain.size() - 1);
for (size_t i = 0; i < chain.size(); i++) {
mat4 absTrans = getAbsTrans(root, chain[i]);
distances[i - 1] = distance(positions[i], positions[i - 1]);
}
- /* glm::vec3 targetPos(sin(d * 10.f), cos(d * 10.f), 0); */
+ // Do the actual IK part
auto newPositions = fabrik(target, positions, distances);
- // Rotate all the nodes so that they are in the correct positions
+ // Move all the nodes so that they are in the correct positions
+ // Don't need to move the root node - it's already in place
for (size_t i = 1; i < chain.size(); i++) {
auto node = chain[i];
mat4 absTrans = getAbsTrans(root, node);
absTrans[3] = vec4(newPositions[i], absTrans[3][3]); // update position in transform
- vec3 oldRelPos = extractPos(aiMatrixToMat4(node.ai.mTransformation));
- vec3 newRelPos = extractPos(absoluteToModelSpace(root, *node.parent, absTrans));
-
- mat4 rot = getRotationToPoint(oldRelPos, newRelPos, distances[i - 1]);
- node.ai.mTransformation = mat4ToaiMatrix(rot * aiMatrixToMat4(node.ai.mTransformation));
-
- /* std::cerr << node.ai.mName.C_Str() << ":\n"; */
- /* printVec3(extractPos(aiMatrixToMat4(node.ai.mTransformation))); */
- /* printVec3(newRelPos); */
- assert(distance(extractPos(aiMatrixToMat4(node.ai.mTransformation)), newRelPos) < 0.0001);
-
- /* absTrans[3] = vec4(newPositions[i], absTrans[3][3]); // update position in transform */
-
- /* mat4 relTrans = absoluteToModelSpace(root, *node.parent, absTrans); */
- /* node.ai.mTransformation = mat4ToaiMatrix(relTrans); */
+ mat4 relTrans = absoluteToModelSpace(root, *node.parent, absTrans);
+ node.ai.mTransformation = mat4ToaiMatrix(relTrans);
}
- // TODO: Now rotate all the nodes so that they face each other
-
- /* for (int i = 0; i < 3; i++) { */
- /* glm::mat4 absTrans(1); */
- /* findNodeTrans(&sceneModel->getRoot()->ai, aiString(jointNames[i]), */
- /* &absTrans); */
- /* glm::mat4 newAbsTrans = absTrans; */
- /* newAbsTrans[3] = glm::vec4(newPositions[i], newAbsTrans[3][3]); */
-
- /* auto node = sceneModel->getRoot()->ai.FindNode(jointNames[i].c_str()); */
+ // Now rotate all the nodes so that they point towards each other
+ // Don't need to rotate the last node - it has nothing to point towards
+ // FIXME: Despite normalizeScale, this is still numerically unstable
+ // and the transformation scales over time!!!
+ for (size_t i = 0; i < chain.size() - 1; i++) {
+ auto node = chain[i]; auto nextNode = chain[i + 1];
+ mat4 oldTrans = aiMatrixToMat4(node.ai.mTransformation);
+ vec3 nextNodePos = extractPos(aiMatrixToMat4(nextNode.ai.mTransformation));
+
+ vec3 up = {0, 1, 0};
+ vec3 dir = -normalize(nextNodePos);
+
+ vec3 v = cross(up, dir);
+ mat3 sscpm = mat3(0, -v[2], v[1],
+ v[2], 0, -v[0],
+ -v[1], v[0], 0);
+ mat4 rot = mat3(1) + sscpm + sscpm * sscpm * (1.f / 1.f + dot(up, dir));
+
+ // very important that we normalize the scale
+ // otherwise we end up with gradually growing models
+ // due to numerical instabaility
+ rot = normalizeScale(rot);
+ node.ai.mTransformation = mat4ToaiMatrix(oldTrans * rot);
+
+ for (auto child: node.getChildren()) {
+ child->ai.mTransformation = mat4ToaiMatrix(normalizeScale(inverse(rot)) * aiMatrixToMat4(child->ai.mTransformation));
+ }
- /* auto newTrans = worldSpaceToModelSpace(node->mParent, newAbsTrans); */
+ }
- /* node->mTransformation = mat4ToaiMatrix(newTrans); */
- /* } */
}
projects / opengl.git / blobdiff