BulletPhysics "setLinearVelocity" does not move

Question

I am trying to create an FPS player with RigidBody using OpenGL and BulletPhysics. The only problem is making the box move. I tried this with setLinearForce, applyForce and many others, but just don't want to move. He still responds to collisions, but if he moves due to a collision (I throw the ball to check his physics) and I press any movement button on my keyboard, it just stops. And if he is still and I press the button to make him move, he simply will not react (remains static).

Here is the class for the player.

#ifndef PLAYER_H #define PLAYER_H #include <iostream> #include <vector> //BulletPhysics #include "Bullet\src\btBulletDynamicsCommon.h" //SDL and OpenGL #include "Link\GLUT\include\glut.h" #include "Link\GLUT\include\GL.h" #include "Link\GLUT\include\GLU.h" #include "Link\SDL\include\SDL.h" using namespace std; class Player { public: btRigidBody* body; btTransform t; btMotionState* motion; Player(); ~Player(); void init(btDynamicsWorld* world, float x, float y, float z, float mass); void RefreshPosition(float x, float z); void Render(); void FreeMemory(btDynamicsWorld* world); }; Player::Player(){} Player::~Player(){} void Player::init(btDynamicsWorld* world, float x, float y, float z, float mass) { t.setIdentity(); t.setOrigin(btVector3(x,y,z)); btBoxShape* obj=new btBoxShape(btVector3(3/2.0, 7/2.0, 3/2.0)); btVector3 inertia(0,0,0); if(mass!=0.0) obj->calculateLocalInertia(mass,inertia); motion=new btDefaultMotionState(t); btRigidBody::btRigidBodyConstructionInfo info(mass,motion,obj,inertia); body=new btRigidBody(info); body->forceActivationState(DISABLE_DEACTIVATION); body->setAngularFactor(0.0); body->setSleepingThresholds(0.0, 0.0); world->addRigidBody(body); } void Player::RefreshPosition(float x, float z) { body->getMotionState()->getWorldTransform(t); Uint8* state=SDL_GetKeyState(NULL); if(state[SDLK_w]) { body->setLinearVelocity(btVector3(x*20, body->getLinearVelocity().y(), z*20)); } body->getMotionState()->setWorldTransform(t); body->setCenterOfMassTransform(t); } void Player::Render() { if(body->getCollisionShape()->getShapeType()!=BOX_SHAPE_PROXYTYPE) return; glColor3f(0.0, 1.0, 0.0); btVector3 extent=((btBoxShape*)body->getCollisionShape())->getHalfExtentsWithMargin(); btTransform t; body->getMotionState()->getWorldTransform(t); float mat[16]; t.getOpenGLMatrix(mat); glPushMatrix(); glMultMatrixf(mat); glBegin(GL_QUADS); glVertex3f(-extent.x(), extent.y(), -extent.z()); glVertex3f(-extent.x(), -extent.y(), -extent.z()); glVertex3f(-extent.x(), -extent.y(), extent.z()); glVertex3f(-extent.x(), extent.y(), extent.z()); glEnd(); glBegin(GL_QUADS); glVertex3f(extent.x(), extent.y(), -extent.z()); glVertex3f(extent.x(), -extent.y(), -extent.z()); glVertex3f(extent.x(), -extent.y(), extent.z()); glVertex3f(extent.x(), extent.y(), extent.z()); glEnd(); glBegin(GL_QUADS); glVertex3f(-extent.x(), -extent.y(), -extent.z()); glVertex3f(extent.x(), -extent.y(), -extent.z()); glVertex3f(extent.x(), -extent.y(), extent.z()); glVertex3f(-extent.x(), -extent.y(), extent.z()); glEnd(); glBegin(GL_QUADS); glVertex3f(-extent.x(), extent.y(), -extent.z()); glVertex3f(extent.x(), extent.y(), -extent.z()); glVertex3f(extent.x(), extent.y(), extent.z()); glVertex3f(-extent.x(), extent.y(), extent.z()); glEnd(); glBegin(GL_QUADS); glVertex3f(-extent.x(), extent.y(), -extent.z()); glVertex3f(-extent.x(), -extent.y(), -extent.z()); glVertex3f(extent.x(), -extent.y(), -extent.z()); glVertex3f(extent.x(), extent.y(), -extent.z()); glEnd(); glBegin(GL_QUADS); glVertex3f(-extent.x(), extent.y(), extent.z()); glVertex3f(-extent.x(), -extent.y(), extent.z()); glVertex3f(extent.x(), -extent.y(), extent.z()); glVertex3f(extent.x(), extent.y(), extent.z()); glEnd(); glPopMatrix(); } void Player::FreeMemory(btDynamicsWorld* world) { world->removeCollisionObject(body); delete body->getMotionState(); delete body->getCollisionShape(); } #endif 

Ok, this is class. Note that RefreshPosition takes two arguments: the position of x and z (I don't want to change the position of y). These two variables represent the direction (from 0 to 1) of the player and are multiplied by 20 to get the speed (maximum value = 20).

Hope I gave you enough information ....

Answer 1

Perhaps the object is deactivated, and then it no longer moves. Then you need to activate it again (find in the documentation how to activate a rigid body using the setActivationState () method)

Objects are deactivated when they become almost stopped. Then they are not activated again until another object applies them to force or does it programmatically.