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Nerdy Nights week 4 Color Palettes, Sprites, second app

Dec 30, 2014 at 4:57:29 AM
user (6)

< El Ripper >
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Originally posted by: Dredster

So, I tried to change the palete by changing the values in .db, but it just came up a black screen. (cut...)

I'm not sure this will help, however, I'll try to help. All this is AFAIK.

You have two palettes of 16 values: one palette is for the sprites, the other is for the background.

Each palette is composed by 4 sub-palettes of 4 values each, the first value (of the four values) of each sub-palette is the same transparency color, which is common in all the (4 x 2 palettes) eight sub-palettes.



This is the sprite palette of Swords and Runes. As you can see, each sub-palette has the same black color in its first slot (I don't know what is the best word to use, I mean the first hex value of each sub-palette); then three other colors. Note that you cannot mix these colors: for instance, you can't have in your game a sprite with a yellow, a green and a blue color using this palette, since these colors are not in the same sub-palette.

So, a single 8x8 sprite, can only use three colors from a specific sub-palette, plus the transparency color.

I hope this helps a little, but I'm not too sure this is what you asked for.

Cheers!

- user

Edit: misspelling.


Edited: 12/30/2014 at 05:00 AM by user

Dec 30, 2014 at 8:41:03 AM
KHAN Games (88)
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(Kevin Hanley) < Master Higgins >
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Originally posted by: Dredster

So, I tried to change the palete by changing the values in .db, but it just came up a black screen. Does the directives only use certain values in the palette based on the Chr rom ? Is this what is meant by High and low byte like the pallet is based off the value of high or low byte ?  Also, not sure if it is covered latter on, but how do I start making a sprite from ground up ? I downloaded Nindraw the learning curve is hard to use. I wanted to fool around with changing the color and sprite formation for learning purposes. I opened up the mario.chr file with textedit and just got some weird unicode. What is that code or should I use like tile molester to open that up and mess with it ?

Yes, the CHR file is a binary file so you can't open it in a text editor and expect to make sense of it.  It is best opened in a program like TileLayerPro or Tile Molester, like you suggested.

And make sure you are changing the values in the correct .db table, since half of it is for background colors and half of it is for sprite colors.  Plus the first value of each set of four colors is the transparency color, like Jack mentioned.  Changing that value for sprites would make no difference since that color doesn't actually visually show up.


Dec 30, 2014 at 12:18:39 PM
Dredster (0)
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(Dred ) < Tourian Tourist >
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I hope this helps a little, but I'm not too sure this is what you asked for.

You and Khan helped a little. I was trying to change the colors in the directive .db. So, they have to have that first transparent color ? Why do they all have to have that ? I'm still not understanding what is meant by high byte and low byte. What is their signifigance and why do you have to set them to a pallete value ?  Looking forward to Swords and Ruins as I do every homebrew. Will it be released on here, Inifite NES lives or RetroUSB ?

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Sorry guys, but I think I got the last copy of Buzz and Waldog from Retrozone.

Dec 30, 2014 at 12:59:13 PM
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< El Ripper >
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Originally posted by: Dredster


I hope this helps a little, but I'm not too sure this is what you asked for.

You and Khan helped a little. I was trying to change the colors in the directive .db. So, they have to have that first transparent color ? Why do they all have to have that ? I'm still not understanding what is meant by high byte and low byte. What is their signifigance and why do you have to set them to a pallete value ?  Looking forward to Swords and Ruins as I do every homebrew. Will it be released on here, Inifite NES lives or RetroUSB ?

So, they have to have that first transparent color ?
Yes.

Why do they all have to have that ?
It is the way the NES handles transparency. Someone more tech-oriented can be more precise about it.

I'm still not understanding what is meant by high byte and low byte. What is their signifigance and why do you have to set them to a pallete value ?

Each colors in the palette is a single byte. Hi/Lo is for addresses and pointers.
But you can just set a "dataline" of 16 hex values and load it up as your palette.
Just remember: #0,#4,#8,#12, i.e. the first byte (i.e. color) of each sub-palette, is transparent.

Will it be released on here, Inifite NES lives or RetroUSB ?
I don't handle the release, just the coding. Updates, when available, will be in the S&R thread.
I fear this is not the correct thread to discuss about it, and that discussing it further would be considered spam in here.
I posted that image just to (try to) explain a concept about sprites palettes.

You and Khan helped a little.
I hope this helped a little more!

Dec 30, 2014 at 1:38:44 PM
Mega Mario Man (58)
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(Tim ) < Kraid Killer >
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Originally posted by: Mega Mario Man

Originally posted by: KHAN Games
$xx,$00,$00,$00, $xx,$00,$00,$00, $xx,$00,$00,$00, $xx,$00,$00,$00 ;sprites
$xx,$00,$00,$00, $xx,$00,$00,$00, $xx,$00,$00,$00, $xx,$00,$00,$00 ;background


The first color in each of the 16 4-byte sections (designated here with x's) is the transparent color. Usually these all need to be the same, but I think basically whatever you have the first value set at, it will automatically make the other 7 first-bytes that same value. So don't be surprised if you try to change that color and nothing happens.
Yup, just learned this tonight trying to program my game. Really threw a wrench into what I was doing. I was thinking I get 4 colors, but really, you get 3 and a bonus forth if it happens to be apart of the background.

 


This is a pretty good depiction about the transparent colors. I swear I wrote a great post explaining this but I can't find it for the life of me.

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Dec 30, 2014 at 2:48:11 PM
KHAN Games (88)
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(Kevin Hanley) < Master Higgins >
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Basically when you play a Nintendo game, the player isn't a square is he? Mario has a shape, Link has a shape, etc, etc. Without a transparent color to tell the Nintendo which pixels to draw invisible, everything would be a square or rectangle.

Jan 3, 2015 at 11:04:31 PM
Dredster (0)
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(Dred ) < Tourian Tourist >
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Originally posted by: KHAN Games

Basically when you play a Nintendo game, the player isn't a square is he? Mario has a shape, Link has a shape, etc, etc. Without a transparent color to tell the Nintendo which pixels to draw invisible, everything would be a square or rectangle.

ahhh, that makes sense now. There are only two paletes one for sprites and one for background ? All colors that are represented within a game exist within these two palettes ? Their adress in the PPU is brought up by the accumulator through operands in the PRG Rom. Does that make any sense ? Am I getting this at all ?

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Sorry guys, but I think I got the last copy of Buzz and Waldog from Retrozone.

Jan 3, 2015 at 11:47:48 PM
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(Brad Bateman - Strange Brew Games) < King Solomon >
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Originally posted by: Dredster

Originally posted by: KHAN Games

Basically when you play a Nintendo game, the player isn't a square is he? Mario has a shape, Link has a shape, etc, etc. Without a transparent color to tell the Nintendo which pixels to draw invisible, everything would be a square or rectangle.

ahhh, that makes sense now. There are only two paletes one for sprites and one for background ? All colors that are represented within a game exist within these two palettes ? Their adress in the PPU is brought up by the accumulator through operands in the PRG Rom. Does that make any sense ? Am I getting this at all ?
Not really.  You have 4 different palettes for sprites, and 4 different palettes for backgrounds.  Each of these palettes are made up of 3 colors, plus the background color.  In the sprite palette, the background color is actually transparent, so if a sprite is on top of the background, the background will show through.



Feb 25, 2015 at 11:12:42 AM
Farid (0)
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(Farid Abbasi) < Cherub >
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Originally posted by: bunnyboy

Sprite DMA
The fastest and easiest way to transfer your sprites to the sprite memory is using DMA (direct memory access). This just means a block of RAM is copied from CPU memory to the PPU sprite memory. The on board RAM space from $0200-02FF is usually used for this purpose. To start the transfer, two bytes need to be written to the PPU ports:
  LDA #$00
  STA $2003  ; set the low byte (00) of the RAM address
  LDA #$02
  STA $4014  ; set the high byte (02) of the RAM address, start the transfer

It seems that there is a small mistake on the comments, which confused me at first.
First of all RAM is not a suitble word for  $2003, it is Sprite Memory
Then Sprites Memory can address from 00 ~ FF (8bit address range) so it doesn't have any low / high address bytes

Thanks for the great tutorial


Edited: 02/25/2015 at 11:14 AM by Farid

Feb 25, 2015 at 12:20:19 PM
KHAN Games (88)
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(Kevin Hanley) < Master Higgins >
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It's setting the sprites to $0200, which is definitely in RAM.

The comments are referring to the LDA #$00 and the LDA #$02.  Low byte and high byte.


Edited: 02/25/2015 at 12:26 PM by KHAN Games

Feb 25, 2015 at 12:35:29 PM
Mog (140)
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(Mr Mog) < King Solomon >
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Originally posted by: Farid

Originally posted by: bunnyboy

Sprite DMA
The fastest and easiest way to transfer your sprites to the sprite memory is using DMA (direct memory access). This just means a block of RAM is copied from CPU memory to the PPU sprite memory. The on board RAM space from $0200-02FF is usually used for this purpose. To start the transfer, two bytes need to be written to the PPU ports:
  LDA #$00
  STA $2003  ; set the low byte (00) of the RAM address
  LDA #$02
  STA $4014  ; set the high byte (02) of the RAM address, start the transfer

It seems that there is a small mistake on the comments, which confused me at first.
First of all RAM is not a suitble word for  $2003, it is Sprite Memory
Then Sprites Memory can address from 00 ~ FF (8bit address range) so it doesn't have any low / high address bytes

Thanks for the great tutorial

$2003 and $4014 are PPU registers.

See here:
http://wiki.nesdev.com/w/index.ph...



Feb 25, 2015 at 3:06:18 PM
Farid (0)
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(Farid Abbasi) < Cherub >
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Writing #$00 to $2003 sets the OAM address (from $00 to $FF)
Writing #$02 to $4014 sets the CPU RAM address (from $XX00 to $XXFF) and then begins the transfer from CPU RAM to OAM automatically
00 and 02 are not High/low bytes of a single address, they are referring to different addresses

Edit :
fixed a typo : $2014 --> $4014


Edited: 02/25/2015 at 09:32 PM by Farid

Feb 25, 2015 at 3:09:43 PM
KHAN Games (88)
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(Kevin Hanley) < Master Higgins >
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Feb 25, 2015 at 6:01:35 PM
thefox (0)
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(Kalle Immonen) < Meka Chicken >
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Originally posted by: Farid

Writing #$00 to $2003 sets the OAM address (from $00 to $FF)
Writing #$02 to $2014 sets the CPU RAM address (from $XX00 to $XXFF) and then begins the transfer from CPU RAM to OAM automatically
00 and 02 are not High/low bytes of a single address, they are referring to different addresses
This should say $4014 instead of $2014, and the DMA source address doesn't have to be RAM; it can be any address in the memory space (you can do OAM transfers from ROM if you want). Other than that it's correct.

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Apr 27 at 10:40:19 AM
Piputkin3 (0)
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< Cherub >
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How to set the sprite speed?

Eg. The character is at the speed x, ap the missile fired at a speed of 2x. Is it possible to set it somehow

Apr 27 at 11:33:46 AM
Mega Mario Man (58)
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(Tim ) < Kraid Killer >
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Just have the sprite move more pixels per frame.

If your character is moving 1 pixel per frame, increment the missile to move 2 pixels per frame.

Example for:
Character
LDA $0200
CLC
ADC #$01
STA $0200

Missile:
LDA $0210
CLC
ADC #$02 ;Twice as fast
STA $0210

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Edited: 04/27/2017 at 11:34 AM by Mega Mario Man

Apr 27 at 11:50:14 AM
Mega Mario Man (58)
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(Tim ) < Kraid Killer >
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Originally posted by: Mega Mario Man

Just have the sprite move more pixels per frame.

If your character is moving 1 pixel per frame, increment the missile to move 2 pixels per frame.

Example for:
Character
LDA $0200
CLC
ADC #$01
STA $0200

Missile:
LDA $0210
CLC
ADC #$02 ;Twice as fast
STA $0210


To build on this, you can use a variable and change the speed of the missile before moving it x or y pixels per frame.

;In Variables Area
MissileSpeed    .rs 1

;Changing Missile speed in code for whatever reason
LDA #$02          ;You can load this with whatever number you want based on things
STA MissileSpeed

;Adjusting the speed of the missile (assuming $0210 is the direction the missile is moving)
LDA $0210
CLC
ADC MissileSpeed                 ;Move sprite this many pixels
STA $0210


2x Character Speed
If you want the missile to be twice as fast as the character, you can do this.

;In Variables Area
CharacterSpeed    .rs 1
MissileSpeed    .rs 1

;Changing Missile speed in code for whatever reason
LDA CharacterSpeed             ;Current number of pixel per frame the character is moving
CLC
ADC CharacterSpeed 
STA MissileSpeed                 ;CharacterSpeed + CharacterSpeed = MissileSpeed

;Adjusting the speed of the missile (assuming $0210 is the direction the missile is moving)
LDA $0210
CLC
ADC MissileSpeed                 ;Move sprite this many pixels
STA $0210

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Apr 27 at 2:52:13 PM
Piputkin3 (0)
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< Cherub >
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It's slower than ADC #$01?

Apr 27 at 3:16:22 PM
Mega Mario Man (58)
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(Tim ) < Kraid Killer >
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Originally posted by: Piputkin3

It's slower than ADC #$01?
With what I posted, the Missile is 2x faster than the character. I hope that is what you are asking, I'm not sure what "It" is.

 

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Apr 27 at 3:40:13 PM
Piputkin3 (0)
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< Cherub >
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I will ask another question, can you determine the sprite rate of less than 1?

Apr 27 at 3:57:47 PM
user (6)

< El Ripper >
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Originally posted by: Piputkin3

I will ask another question, can you determine the sprite rate of less than 1?


Yes, using a further byte of RAM.
Example: you store somewhere (e.g. variable FOO) the value HEX00.
then each NMI you add HEX40 to that variable.
each four MNIs the variable will reach "HEX100" (which is HEX FF+1 ) reset to zero and trigger the carry flag.
When the carry flag is triggered, you advance by 1 pixel.
So, you advance by 1/4 of pixel each NMI.
tell me if this helps.  

Apr 27 at 4:03:12 PM
Mega Mario Man (58)
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(Tim ) < Kraid Killer >
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Originally posted by: Piputkin3

I will ask another question, can you determine the sprite rate of less than 1?

Yes. Instead of moving 1 pixel per frame, you move 1 pixel every other frame, every third frame, etc. However slow you want it to go.

The way I would tackle this by using a counter variable to skip frames.

;Variables
MissileSpeedCounter   .rs 1

;Code to Move Missile
INC MissileSpeedCounter      
LDA MissileSpeedCounter
CMP #$02                           ;Adjust this value depending on how many frames you want to skip, here I'm going every other frame. You can use a variable here if you want different speeds
BNE .SkipMoveMissile         ;Skip moving the missile this frame if not equal to #$02
     LDA $0210
     CLC
     ADC #$01
     STA $0210        ;Move Missile 1 pixel
    
     LDA #$00
     STA MissileSpeedCounter         ; Reset counter back to #$00
.SkipMoveMissile :



 

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Apr 27 at 4:06:30 PM
Mega Mario Man (58)
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(Tim ) < Kraid Killer >
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Originally posted by: user
 
Originally posted by: Piputkin3

I will ask another question, can you determine the sprite rate of less than 1?


Yes, using a further byte of RAM.
Example: you store somewhere (e.g. variable FOO) the value HEX00.
then each NMI you add HEX40 to that variable.
each four MNIs the variable will reach "HEX100" (which is HEX FF+1 ) reset to zero and trigger the carry flag.
When the carry flag is triggered, you advance by 1 pixel.
So, you advance by 1/4 of pixel each NMI.
tell me if this helps.  
I think this may be better touched in the 16-bit math section further a long in the tutorials. This is only lesson #4.   

But yes, that is a shorter way to do this than what I posted if you are wanting to save cycles and RAM space.

 

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Edited: 04/27/2017 at 04:14 PM by Mega Mario Man

Apr 27 at 4:43:38 PM
user (6)

< El Ripper >
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Originally posted by: Mega Mario Man

Originally posted by: user
Originally posted by: Piputkin3

I will ask another question, can you determine the sprite rate of less than 1?


Yes, using a further byte of RAM.
Example: you store somewhere (e.g. variable FOO) the value HEX00.
then each NMI you add HEX40 to that variable.
each four MNIs the variable will reach "HEX100" (which is HEX FF+1 ) reset to zero and trigger the carry flag.
When the carry flag is triggered, you advance by 1 pixel.
So, you advance by 1/4 of pixel each NMI.
tell me if this helps.
I think this may be better touched in the 16-bit math section further a long in the tutorials. This is only lesson #4.

But yes, that is a shorter way to do this than what I posted if you are wanting to save cycles and RAM space.
 


Indeed.  
What you say makes perfect sense. And nice from you to write a full routine, I was too lazy.  

In the end, I think that providing Piputkin3 two different solutions, won't hurt!