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3 hours ago, Asmusr said:

All I can say is that at the moment I'm interested in developing this project further. But there's currently not much to make a game from, and I don't have any specific idea for a game.

 

I think you first need sprites implemented. According to the frame rate achieved, you will be able to design a game idea that fits the constrains

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Even just a variation on TOD would be cool.  Maybe find a way to implement the "in room" battles in a 3D way?  It could still be turn based, but just a switch-up on the visuals.

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9 hours ago, jrhodes said:

"Hunt the wumpus 3D"

Yes, that is a great idea! But there are some challenges with "seeing" stuff. Or maybe signs? Could replace the overview?

But a simple shoot em up is also a start! Slow speed and speeding it up. One bady and adding on badys for next level.

Or a shoot em up that is a maze that you have to get to the end to get to the next maze. Dead ends and some of them has more amo, first aid kit and so on.

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17 hours ago, artrag said:

I think you first need sprites implemented. According to the frame rate achieved, you will be able to design a game idea that fits the constrains

Exactly. Without anything other than walls very little interaction is possible. But adding big zooming sprites using a limited number of character tiles is quite challenging.  

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I was wondering to myself how a raycaster could work in 9918A multicolor 64x48 pixel mode, if it would even be possible with its unusual screen and pattern table layout.  There would need to be a way to quickly render columns of pixels, but each character pattern contains two pixels side by side.  Suppose we process two columns at once and combine the pixels into each byte written to the pattern table.  If every other column data is pre-shifted by 4 bits, we could then bitwise-OR the two column bytes together, which should be pretty fast.  The screen table is initialized with columns of 0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5 adding 6 to every byte when moving to the next column.  Now to draw the screen, the pattern table can be written sequentially, each byte drawing two side-by side pixels, moving downward.  I coded up a screen drawing function that runs from scratchpad RAM to see how fast it goes, and I get 83190 cycles (~28ms) per screen update.  May I copy your raycasting code to test my multicolor screen drawing function?

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9 hours ago, PeteE said:

I was wondering to myself how a raycaster could work in 9918A multicolor 64x48 pixel mode, if it would even be possible with its unusual screen and pattern table layout.  There would need to be a way to quickly render columns of pixels, but each character pattern contains two pixels side by side.  Suppose we process two columns at once and combine the pixels into each byte written to the pattern table.  If every other column data is pre-shifted by 4 bits, we could then bitwise-OR the two column bytes together, which should be pretty fast.  The screen table is initialized with columns of 0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5 adding 6 to every byte when moving to the next column.  Now to draw the screen, the pattern table can be written sequentially, each byte drawing two side-by side pixels, moving downward.  I coded up a screen drawing function that runs from scratchpad RAM to see how fast it goes, and I get 83190 cycles (~28ms) per screen update.  May I copy your raycasting code to test my multicolor screen drawing function?

I did that myself (a multicolor renderer without a raycaster) a while back, and I am indeed considering if that's the way to go with this project. You're welcome to try your own renderer with my code, of course.

 

 

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Here's the routine I used to draw two columns given top, height and color.

 

Spoiler
********************************************************************************
*
* Display two vertical multicolor strips
*
* R3: Strip 1 structure (top, height, color)
* R4: Strip 2 structure (top, height, color)
* R14: VDPWD
* VDP write address must already be set up
*
* On return R3 and R4 are incremented by 6.
* R0-R12 are modified.
*
STRIP  MOV  R11,*R15+        * Push return address onto the stack
      MOV *R3+,R5             * Get top 1
      MOV *R4+,R6             * Get top 2
      MOV *R3+,R7             * Get bottom 1
      MOV *R4+,R8             * Get bottom 2
      MOV *R3+,R9             * Get color 1
      MOV *R4+,R10         * Get color 2
*     Two sky pixels
      C   R5,R6           * Compare top 1 and top 2
      JGT STRIP1
      MOV R5,R2           * Get number of sky rows to display from strip 1
      JMP STRIP2
STRIP1 MOV R6,R2           * Get number of sky rows to display from strip 2
STRIP2 JEQ STRIP4          * Move on if zero
      MOVB    @SKY,R1             * Get sky pixel colors
STRIP3 BL  @VDPCPY
*     One sky pixel, one strip pixel 
STRIP4 MOV R6,R2           * Get top 2
      S   R5,R2           * Top 2 - top 1
      JEQ STRI19          * If zero this section can be skipped
      JLT STRIP5          * Jump if strip 1 starts after strip 2
      MOV R9,R1            * Get color of strip 1
      SLA R1,4            * Move to 1st nybble
      SOCB    @SKY2,R1         * Combine with sky pixel colors
      MOV R6,R12          * Save top 2 as the start of next section
      JMP STRIP6
STRIP5 NEG R2             * Make counter positive
      MOV R10,R1          * Get color of strip 2
      SOCB    @SKY1,R1         * Combine with sky pixel colors
      MOV R5,R12          * Save top 1 as the start of next section
STRIP6 BL  @VDPCPY
      JMP STRIP7
STRI19 MOV R6,R12          * Save top 2 as the start of next section     
*     Two strip pixels
STRIP7 C   R7,R8           * Compare bottom 1 and bottom 2
      JGT STRIP8
      MOV R7,R2           * Get bottom 1
      S   R12,R2          * Subtract end of previous section
      JEQ STRI17          * If zero this section can be skipped
      MOV R7,R12          * Save bottom 1 as the start of next section
      JMP STRIP9
STRIP8 MOV R8,R2           * Get bottom 2
      S   R12,R2          * Subtract end of previous section
      JEQ STRI17          * If zero this section can be skipped
      MOV R8,R12          * Save bottom 2 as the start of next section
STRIP9 MOV R9,R1           * Get color of strip 1
      SLA R1,4            * Move to 1st nybble
      SOC     R10,R1          * Combine with color of strip 2
STRI10 BL  @VDPCPY
      JMP STRI11
STRI17 MOV R7,R12          * Save bottom 1 as the start of next section
*     One floor pixel, one strip pixel
STRI11 MOV R8,R2           * Get bottom 2
      S   R7,R2           * Subtract bottom 1
      JEQ STRI18          * If zero this section can be skipped
      JLT STRI12          * Jump if strip 1 ends after strip 2
      MOV R10,R1           * Get color of strip 2
      SOCB    @FLOOR1,R1       * Combine with sky pixel colors
      MOV R8,R12          * Save bottom 2 as the start of next section
      JMP STRI13
STRI12 NEG R2             * Make counter positive
      MOV R9,R1            * Get color of strip 1
      SLA R1,4            * Move to 1st nybble
      SOCB    @FLOOR2,R1       * Combine with sky pixel colors
      MOV R7,R12          * Save bottom1 as the start of next section
STRI13 BL  @VDPCPY
      JMP STRI14
STRI18 MOV R8,R12          * Save bottom 2 as the start of next section      
*     Two floor pixels
STRI14 LI  R2,48
      S   R12,R2
      JEQ STRI16
      MOVB    @FLOOR,R1
STRI15 BL  @VDPCPY
*     Return
STRI16 DECT R15                * Pop return address off the stack
      MOV  *R15,R11
       B   *R11

SKY       BYTE    >77
SKY1   BYTE    >70
SKY2   BYTE    >07
FLOOR  BYTE    >EE
FLOOR1 BYTE    >E0
FLOOR2 BYTE    >0E

*// STRIP

*********************************************************************
*
* Fast VDP copy
*
* R1: Byte to copy (in MSB)
* R2: Number of bytes to copy
* R14: VDPWD address
*
VDPCP  MOV R2,R0
      SRL R0,3            * Number of groups of 8
      JEQ VDPC2
VDPC1  MOVB    R1,*R14
      MOVB    R1,*R14
      MOVB    R1,*R14
      MOVB    R1,*R14
      MOVB    R1,*R14
      MOVB    R1,*R14
      MOVB    R1,*R14
      MOVB    R1,*R14
      DEC R0
      JNE VDPC1
      ANDI    R2,>0007         * Isolate number of remaining bytes
      JEQ VDPC3
VDPC2  MOVB    R1,*R14
      DEC R2
      JNE VDPC2
VDPC3  B   *R11
VDPCPE
*// VDPCP

 

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Posted (edited)

a simple playable demo in which at the beginning the maze is invisible (but the walls block you) and you can find buckets of of paint with which to color and make the walls appear.

Edited by Elia Spallanzani fdt
Correction
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Posted (edited)

Here's the latest version. I don't have time to write about it now, but it's progressing really well. I fixed an issue with the height calculation which means that the walls are no longer rounded.

 

 

Your challenge for today: find the two multi color striped areas. 

raycaster.rpk raycaster8.bin

Edited by Asmusr
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5 minutes ago, Elia Spallanzani fdt said:

Fantastic. Just one thing: the weapon shouldn't jump when you're stationary.

I use the weapon to see the frame rate.

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Posted (edited)

This really a cool project, thanks asmusr for working on this and congrats of making it work!

 

Incidentally it also is a pretty much perfect test platform my new project, the StrangeCart cartridge for the TI-99/4A. This is something I wanted to try out for ages, but got around of implementing it only now.

Here I have my TI-99/4A running your raycaster from the StrangeCart cartridge. 32k RAM expansion is provided by ET-PEB. The USB cables are used for debugging the cartridge and not needed to run.

large.IMG_1123-1.jpg.cf567a7ef1a79674b02ea3a8ddcb96c5.jpg

Edited by speccery
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2 hours ago, Asmusr said:

Here's the latest version. I don't have time to write about it now, but it's progressing really well. I fixed an issue with the height calculation which means that the walls are no longer rounded.

 

 

The challenge for today: find the two multi color striped areas. 

raycaster.rpk 7.34 kB · 2 downloads raycaster8.bin 32 kB · 3 downloads

Spear of DesTI99y ;-)

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4 hours ago, Asmusr said:

Here's the latest version. I don't have time to write about it now, but it's progressing really well. I fixed an issue with the height calculation which means that the walls are no longer rounded.

That's pretty great.. just a few years ago we still weren't sure this was even feasible, and there it is, better than we could have hoped! ;)

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It's interesting that this doesn't really require 32K RAM. As my code is now it does, but I think it could run almost as fine from a ROM cart. The only updated data in 32K are the positions of the enemies, and those could be moved to VDP RAM.

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