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POBulletPhysics "setLinearVelocity" not moving
 

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  1. POBulletPhysics "setLinearVelocity" not moving
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    <p>I'm trying to create an FPS player that has a RigidBody using OpenGL and BulletPhysics. The only problem is to make the box move. I tried it with setLinearForce, applyForce and many others but is just don't want to move. It still responds to collisions but if it is moving because of a collision (I'm throwing a ball to test its physics) and I press any movement button on my keyboard it just stops. And if it is still and i press the button to make it move it just won't react (stays static).</p> <p>Here is the class for the player.</p> <pre class="lang-cpp prettyprint-override"><code>#ifndef PLAYER_H #define PLAYER_H #include &lt;iostream&gt; #include &lt;vector&gt; //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-&gt;calculateLocalInertia(mass,inertia); motion=new btDefaultMotionState(t); btRigidBody::btRigidBodyConstructionInfo info(mass,motion,obj,inertia); body=new btRigidBody(info); body-&gt;forceActivationState(DISABLE_DEACTIVATION); body-&gt;setAngularFactor(0.0); body-&gt;setSleepingThresholds(0.0, 0.0); world-&gt;addRigidBody(body); } void Player::RefreshPosition(float x, float z) { body-&gt;getMotionState()-&gt;getWorldTransform(t); Uint8* state=SDL_GetKeyState(NULL); if(state[SDLK_w]) { body-&gt;setLinearVelocity(btVector3(x*20, body-&gt;getLinearVelocity().y(), z*20)); } body-&gt;getMotionState()-&gt;setWorldTransform(t); body-&gt;setCenterOfMassTransform(t); } void Player::Render() { if(body-&gt;getCollisionShape()-&gt;getShapeType()!=BOX_SHAPE_PROXYTYPE) return; glColor3f(0.0, 1.0, 0.0); btVector3 extent=((btBoxShape*)body-&gt;getCollisionShape())-&gt;getHalfExtentsWithMargin(); btTransform t; body-&gt;getMotionState()-&gt;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-&gt;removeCollisionObject(body); delete body-&gt;getMotionState(); delete body-&gt;getCollisionShape(); } #endif </code></pre> <p>Ok, this is the class. Note that the RefreshPosition takes two arguments: the x and z position (I don't want to change the y position). This two variables represent the direction (0 to 1) of the player and are multiplied by 20 to result the velocity (maximum value = 20). </p> <p>I hope I gave you sufficient information....</p>
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    1. PTQuestion
    1. USNicol Bolas
    1. USTiago Salzmann
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      1. POBulletPhysics "setLinearVelocity" not moving
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      1. VTUpMod
    1. COCan you give a more concise snippet that represents the error, or remove the referenced elements not included in the code so we can test it more easily?
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      1. POBulletPhysics "setLinearVelocity" not moving
      1. USBoppreH
    2. COthe only problem is that it does not work (setLinearVelocity). Sometimes i run the program and it works for just 30 seconds at the beginning and then it stops and don't respond to the keyboard
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      1. POBulletPhysics "setLinearVelocity" not moving
      1. USTiago Salzmann
    3. COI know this is a very old thread but I am having the exact same issue where when I move the object, it moves but the moment it stops I cant move the object anymore. I want to know how you solved this issue. Thanks
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      1. POBulletPhysics "setLinearVelocity" not moving
      1. USGasim
 

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