Developing NES game (cc65) 07 and controller with C language

07、 controller

 

NES There are 2 Controller ports . You can use port 4016 and 4017 Read them at any time . Behind the scenes , It will close and open 4016 port , Then read the button once ,1 Button ,8 Secondary read , Then convert them into variables .

 

Neslib, How to use this function .

 

pad1 = pad_poll(0) Read controller 1.

pad2 = pad_poll(1) Read controller 2.

 

If you want to get the value without repeatedly reading the handle, you can use the following method to get the value again .

pad_state(0)

pad_state(1)

 

pad_trigger() Get the most recently pressed button . I don't use it .

If you use , The order will be pad_trigger() And then there was pad_state(), Because the trigger runs pad_poll() function .

 

I wrote a function get_pad_new(), It is similar to pad_trigger(), In addition to running first pad_poll() And then run get_pad_new().

pad1 = pad_poll(0);

pad1_new = get_pad_new(0);

 

pad1_new Will get the recently pressed button . If the pause key is pressed , We don't want him to pause continuously 、 recovery 、 Pause 、 The cycle of recovery . It should be to release the pause key , Press again to change the current state （ Pause and press again to return to the running state ）

 

pad1 It's a 8 Bit char type , Is precisely 8 Field position of buttons . We need to use the bit ID to judge which button is pressed .

 

 

 

if(pad1_new & PAD_START){

Pause();

}

 

 

 

 

 

Spirit and collision

 

I set up separate controls for each elf , When they collide, they change the background color .

 

 

if（collision）{

pal_col（0,0x30）;

}

 

 

 

I wrote a function , You can test whether any sprite object has been touched . The function needs 2 individual 4 Byte object ( Or an array ), The byte order is (x,y, wide , high )

I let this function accept 2 individual void The pointer , I hope to use different types of object structures in the future . At least , This is a plan .

 

Collision detection code example

collision = check_collision(&BoxGuy1, &BoxGuy2);

 

We can also put him directly into if Use... In conditions

if(check_collision(&BoxGuy1, &BoxGuy2))

 

Consider using ASM Assembly mode optimizes this code

 

 

if((obj1_right >= obj2_left) &&

 

(obj2_right >= obj1_left) &&

 

(obj1_bottom >= obj2_top) &&

 

(obj2_bottom >= obj1_top)) return 1;

 

else return 0;

 

 

 

In case of collision, the screen background turns white , It can be confirmed that he has taken effect .

There will be some problems when one elf leaves the other half , But this has met the demand .

 

https://github.com/nesdoug/08_Pads/blob/master/Pads.c

 

https://github.com/nesdoug/08_Pads