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I canot finish it ( I think im so bad )

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Started by alx123 September 18, 2007 11:29 PM

1 comment, last by NestorPL 16 years, 7 months ago

alx123

118

Author

September 18, 2007 11:29 PM

Well I have tried to make this easy esasy game but is to dificcult. First I scrap a lot of things in my code and began using Classes. Everithing I dont know is: Make The ball bounce. Make the ball bounce in different positions. The AI is the last part that I want to make since collision detection is more difficult I think. I tried to make the "collision" like I have seen in some code before but i dont undersant what to do then void Collision(Rpaddle &pad, Lpaddle &lpad) { if(.......) return true. else.......... } Here is the code:


//Ball, Paddle classes
#ifndef CLASES_H
#define CLASES_H

class PaddleDerecho		//The Right Paddle
{
public:
		 PaddleDerecho(){this->xPos = 0.0;}
		 GLfloat xPos;		//THE Y POSITION
};PaddleDerecho Derecho;

class PaddleIzquierdo    // The left Paddle
{
public:
		 PaddleIzquierdo() { this->yPos = 0.0;}
		 GLfloat yPos;		 //Y position
};PaddleIzquierdo Izquierdo;

class Ball
{
public:
		GLfloat PosX; //X position
		GLfloat PosY;  //Y position
		Ball(){ this->PosX = 0.0; this->PosY = 0.0;}
		//Collision
		bool checkCollision(PaddleDerecho &unDerecho, Ball &unBalon, PaddleIzquierdo &isquierdo);
}; Ball Balon;
#endif


//main
#include <glut.h>
#include "Clases.h"

const float UpWall = 1.48;
const float DownWall = -1.257;

//This is my function that TRIES to detect the collision betewn the ball and paddles and wall
bool Ball::checkCollision(PaddleDerecho &unDerecho, Ball &unBalon, PaddleIzquierdo &isquierdo)
{
	if(unBalon.PosX >= 1.8)
		return false;
	 if(unBalon.PosX >= -1.8)
		return false;
	 if(unBalon.PosY <= UpWall)
		 return false;
	 if(unBalon.PosY <=  DownWall)
		 return false;
	else 
		return true;
} //But I dont know what more to do
//I see some games making it like it


void update(int w);
void keyboard(int key,int a,int b);
void display();
void init(); 
void handleResize(int w, int h);

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutInitWindowSize(400, 400); 
	glutCreateWindow("Pong");
	init(); 
	glutDisplayFunc(display);
    glutSpecialFunc(keyboard);
	glutReshapeFunc(handleResize);
	glutTimerFunc(25,update,0);
	glutMainLoop(); 
}

void init() 
{
	glEnable(GL_DEPTH_TEST); 
}

void handleResize(int w, int h) 
{ 
	glViewport(0, 0, w, h);
	glMatrixMode(GL_PROJECTION); 
	glLoadIdentity(); 
	gluPerspective(45.0,(double)w / (double)h, 1.0, 200.0);  
}

void display()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glMatrixMode(GL_MODELVIEW); 
//Left Paddle
	glLoadIdentity(); // Reset transformation matrix
	glTranslatef(0, Izquierdo.yPos, 0); 
	glBegin(GL_QUADS);
		glVertex3f(-2.1f, -0.6f, -5.0f);
		glVertex3f(-1.8f, -0.6f, -5.0f);
		glVertex3f(-1.8f,  0.4f, -5.0f);
		glVertex3f(-2.19f, 0.4f, -5.0f);
	glEnd(); 

//Right Paddle
	glLoadIdentity(); // Reset the transformation matrix 
	glTranslatef(0,Derecho.xPos,0);
	glBegin(GL_QUADS);
		glVertex3f(2.1, -0.6f, -5.0f); 
		glVertex3f(1.8, -0.6f, -5.0f);
		glVertex3f(1.8,  0.4f, -5.0f);
		glVertex3f(2.1,  0.4f, -5.0f);
	glEnd(); 

//Ball
	glLoadIdentity();
	glTranslatef(Balon.PosX,Balon.PosY, 0);
	glBegin(GL_QUADS);
		glVertex3f(-0.1f, -0.3f, -5.0f); 
		glVertex3f( 0.1f, -0.3f, -5.0f);
		glVertex3f( 0.1f, -0.1f, -5.0f);
		glVertex3f(-0.1f, -0.1f, -5.0f);
	glEnd(); 


//Begin The top wall
	glLoadIdentity();
	glBegin(GL_QUADS);
		glVertex3f( 5.2f, 2.1f, -5.0f); 
		glVertex3f(-2.2f, 2.1f, -5.0f);
		glVertex3f(-2.2f, 1.9f, -5.0f);
		glVertex3f( 5.2f, 1.9f, -5.0f);
//Begin Down Wall
		glVertex3f( 5.2f, -2.1f, -5.0f); 
		glVertex3f(-2.2f, -2.1f, -5.0f);
		glVertex3f(-2.2f, -1.9f, -5.0f);
		glVertex3f( 5.2f, -1.9f, -5.0f);
	glEnd();
glutSwapBuffers();
}

void keyboard(int key,int a,int b)
{


	switch (key)
	{
	 //Player 1
		case  GLUT_KEY_UP:
			Izquierdo.yPos += 0.1;			// Move up
				if(Izquierdo.yPos >= UpWall)		//"Up WallDetection"
				{ 
					Izquierdo.yPos = UpWall;  
				} 	
		break;

		case GLUT_KEY_DOWN:
		       Izquierdo.yPos -= 0.1;				//Move down
				if(Izquierdo.yPos <= DownWall)		//"Down Wall Detection"
				{ 
					Izquierdo.yPos = DownWall; 
				} 
	     break;
  //Player 2 It is gonna be the Computer
	} 
	display();
}

void update(int w)
{
	Balon.PosX += 0.1;
	bool Registro = Balon.checkCollision(Derecho,Balon,Izquierdo);
	glutPostRedisplay();
	glutTimerFunc(25,update,0);
	
}

I know is a mess but I first want to do everithing first and when everithing works I will like change a lot from it

xibo

110

September 18, 2007 11:35 PM

if(unBalon.PosX >= 1.8)		return false;	 if(unBalon.PosX >= -1.8)		return false;	 if(unBalon.PosY <= UpWall)		 return false;	 if(unBalon.PosY <=  DownWall)		 return false;	else 		return true;

condition 1 is implied by condition 2 meethinks. and more or less the same can be said about conditions 3 and 4 once the values of UpWall and DownWall are evaluated. Don't you want to replace the gequal with lequal somewhere ( e.g. at condition 1 )?
Furthermore you don't need an else there because you can't reach it if one of your if-s was true anyway ( because you returned )

NestorPL

138

September 18, 2007 11:52 PM

Hey,

Let's start from the beginning. Please keep the code in english, re-edit it for submission if you have to, variables such az Iziquerdo won't help us understand your code.

Now, let's move on to bouncy bouncy.

First of all you need to start thinking with objects. The ball is an object.

Most important thing for us is the VECTOR along which our ball moves. I assume that you're trying to do that in 2d.

class Vector2d{ public:  float x;  float y;  ...}

We assume that the vector is anchored at the position of your ball. The length of the vector is the speed of the ball. This means that in the next frame the ball will appear at ballX = ballX + vector.x , ballY= ballY+ vector.y

When the ball hits something, it will bounce at speed reduced by friction, against the normal (perpendicular to surface) vector of the surface, using the same angle.
To learn what are normal vectors, and how bouncing works, you will need to fetch your math book, and possibly a physics book for the bounce thing. Or simply draw it on a piece of paper with a grid.

Collision detection is something you will have to think a lot about. Generally, you need to check your ball against ALL collidable objects in the scene (reducing this number to speed up computation is quite a task in itself, so let's disregard this).

The basic idea is to encase every object in a bounding volume, like a box, and then see if boxes overlap for collision.

Basic sphere->box collision test can look like this :

bool AABB_Sphere(nSphere sphere,int mode) 	{		// false for no collision, true for collision, how smart is that? :)				float d=0.0;							float sphereaxis[3]={sphere.center.x,sphere.center.y,sphere.center.z};			float minaxis[3]={BV.vmin.x,BV.vmin.y,BV.vmin.z};			float maxaxis[3]={BV.vmax.x,BV.vmax.y,BV.vmax.z};						for (int i=0;i<3;i++)			{				if (sphereaxis < minaxis)				{					d += (sphereaxis - minaxis)*(sphereaxis - minaxis);				}				else if (sphereaxis > maxaxis)				{					d += (sphereaxis - maxaxis)*(sphereaxis - maxaxis);				}			}			// if sphere intersects the box			if (d < (sphere.radius*sphere.radius))			{				return true;			} return false ; // false in all other cases}

This is for 3d. For 2d test, you need to simply reduce the number of tested axes to two. Basically, if the distance from the box is less than radius^2 there is a collision. This is quite an old code of mine, and I'm not entirely sure why it's sphere^2 anymore :P I'm quite certain this method was taken from some book, but Real Time Rendering 2nd ed didn't have it when i looked just now.

When there is a collision, you perform the bounce mentioned above.

Unfortunately this is not an easy matter, and WILL require a lot of thought and thinking about the underlying geometry of objects you are using, and a LOT of maths to make it spin.
Read up on vectors, normal vectors, normalizing, bouncing, etc. High-school level math manual should have most of this stuff.

For the rest, if you're interested, mentioned real-time rendering 2nd ed will be useful, however it has a lot of stuff you won't ever need.

Hope this somewhat sketchy rundown helped you grasp what you're being pitted against.

Good luck!

-- Lukasz SzczepanskiAssociate Producer, Gamelion Studios - Polandhttp://nestor.vg Periodic gaming and design rantings.

I canot finish it ( I think im so bad )

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I canot finish it ( I think im so bad )

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