BulletPhysics "setLinearVelocity" not moving
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).
Here is the class for the player.
#ifndef PLAYER_H
#define PLAYER_H
#include <iostream>
#include <vector>
//BulletPhysics
#include "BulletsrcbtBulletDynamicsCommon.h"
//SDL and OpenGL
#include "LinkGLUTincludeglut.h"
#include "LinkGLUTincludeGL.h"
#include "LinkGLUTincludeGLU.h"
#include "LinkSDLincludeSDL.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 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).
I hope I gave you sufficient information....
Perhaps the object becomes deactivated and then it doesn't move anymore. Then you have to activate it again (search in the documentation how to activate a rigid body with the setActivationState() method)
Objects become deactivated when they become almost stopped. Then they don't activate again until another object applies them a force or you do it programmatically.
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