Question

I am using box2d and cocos2d for my jump based game. I need to jump the character on platforms as they come.

Any ideas of how to do it using box2d ?

Answer 1

You try this:

//OBSTACLE_1:
    {
        CCSprite *sprite = [CCSprite spriteWithFile:@"hungObstacle1_C2H18.png"];
        sprite.position = ccp(1568,704);
        sprite.tag = 4;
        [self addChild:sprite];

        //SHAPE :
        {
            b2BodyDef bodyDefinition;
            bodyDefinition.type = b2_dynamicBody;
            bodyDefinition.position.Set(1568/PTM_RATIO, 704/PTM_RATIO);
            bodyDefinition.userData = sprite;

            body = world->CreateBody(&bodyDefinition);//body is a b2Body

            // Create body shape
            b2PolygonShape bodyShape;
        //row 1, col 1
        int num = 8;
        b2Vec2 verts[] = {
            b2Vec2(14.5f / PTM_RATIO, -27.0f / PTM_RATIO),
            b2Vec2(19.5f / PTM_RATIO, -11.0f / PTM_RATIO),
            b2Vec2(19.5f / PTM_RATIO, 11.0f / PTM_RATIO),
            b2Vec2(16.5f / PTM_RATIO, 24.0f / PTM_RATIO),
            b2Vec2(-14.5f / PTM_RATIO, 24.0f / PTM_RATIO),
            b2Vec2(-19.5f / PTM_RATIO, 16.0f / PTM_RATIO),
            b2Vec2(-19.5f / PTM_RATIO, -13.0f / PTM_RATIO),
            b2Vec2(-12.5f / PTM_RATIO, -26.0f / PTM_RATIO)
        };
        bodyShape.Set(verts, num);

            // Create shape definition and add to body
            b2FixtureDef bodyFixtureDefinition;
            bodyFixtureDefinition.shape = &bodyShape;
            bodyFixtureDefinition.density = 5000.0f;
            bodyFixtureDefinition.friction = 1.0f;
            bodyFixtureDefinition.restitution = 1.0f;//*        
            fixture=body->CreateFixture(&bodyFixtureDefinition);            
        }           
    }

*NOTE:by setting restitution to 1 body will keep jumping all the time just need little force