+xucaen Posted January 11, 2005 Share Posted January 11, 2005 Hi, I'm still reading Andrew's tutorial and I'm sure I'll figure this out eventually. I'm certain it's a timing issue.. probably have some wsyncs in the wrong place.. But anyways, I'm only testing moving a sprite up, down, left and right. There is also a simple reflected playfield on the bottom 6 scanlines. When my sprite reaches the left side of the screen one of the top bits disappears, almost as is there is an invisible line doesn the side. I'm attaching two screen shots, the first shows what the screen looks like when it first starts up, the second shows when the sprite reaches the left side. I guess what I'm looking for are some possibilities for me to look at, I don't anyone to hand hold me.. not unless you really care. Thanks! Jim Quote Link to comment Share on other sites More sharing options...
Big Player Posted January 11, 2005 Share Posted January 11, 2005 I have no idea how to help you, but that first picture looks like it could be the start of a cool Tempest port. Quote Link to comment Share on other sites More sharing options...
Cybergoth Posted January 11, 2005 Share Posted January 11, 2005 Hi there! Could be anything. Post the source for a diagnose. Greetings, Manuel Quote Link to comment Share on other sites More sharing options...
+xucaen Posted January 12, 2005 Author Share Posted January 12, 2005 Could be anything. Post the source for a diagnose. Hi, I'm going to do more reading on sprites. I only got up to session 14 then skipped up to session 22, so I definately missed some important information. I cleaned it up the best I could, plus pulled out all my subroutine calls as soon as I learned that each one uses up 6 cycles to call, then 6 cycles to RTS. Yikes! Next I'm going to count the cycles and see if this is a timing issue which I think it is. So, for anyone who may be interested here's my source. I appreciate any hints, but I'm not looking for a flat out answer.. that would take all the fun and learning out of it. processor 6502 include vcs.h include macro.h ;set origin to the start of the 4k rom SEG ORG $F000 ; vet up variables YPosP0 = $80; first address in RAM HeightP0 = $81 SpeedCounter = $83 ScanLineCount = $84 Reset ;Clear RAM and all TIA registers ldx #0 lda #0 Clear sta 0,x inx bne Clear ;total 9 bytes! InitializeVariables lda #90 sta YPosP0 lda #186;we have 6 lines of playfield at the botton so ;192-6=186 sta ScanLineCount ;EndInitializeVariables ;//////////////////////////////////////// StartOfFrame; Beginning of the game ;//////////////////////////////////////// ;===================================== ; VerticalSync ;top 3 scanlines ;using macro. this also stops vsync VERTICAL_SYNC ;===================================== ;===================================== ;VerticalBlank ;37 scanlines ldx #37 ; 37 scanlines of vertical blank... vblankloop sta WSYNC dex bne vblankloop ; check the joystick controls here ;;;;;;;;;;;;;;; ;MovePlayers ;;;;;;;;;;;;;;; ; for up and down, we INC or DEC ; the Y Position ; MoveDown LDA #%00010000 ;Down? BIT SWCHA BNE EndMoveDown LDA ScanLineCount CMP YPosP0 BEQ ResetYDown INC YPosP0 JMP EndMoveDown ResetYDown LDA #11 STA YPosP0 EndMoveDown ; MoveUp LDA #%00100000 ;Up? BIT SWCHA BNE EndMoveUp LDA #11 CMP YPosP0 BEQ ResetYUp DEC YPosP0 JMP EndMoveUp ResetYUp LDA ScanLineCount STA YPosP0 EndMoveUp ;assum horiz speed will be zero LDX #0 ; MoveLeft LDA #%01000000 ;Left? BIT SWCHA BNE EndMoveLeft LDX #%00010000 ;a 1 in the left nibble means go left ;; moving left, so we need the mirror image LDA #%00001000 ;a 1 in D3 of REFP0 says make it mirror STA REFP0 EndMoveLeft ; MoveRight LDA #%10000000 ;Right? BIT SWCHA BNE EndMoveRight LDX #%11110000 ;a -1 in the left nibble means go right... ;; moving right, cancel any mirrorimage LDA #%00000000 STA REFP0 EndMoveRight STX HMP0 ;set the move for player 0 ;testing. trying to fix obstruction on left side of screen LDA WSYNC ;;;;;;;;;;;;;;;; ;EndMovePlayers ;;;;;;;;;;;;;;;; STX VBLANK ;EndVerticalBlank ;======================================== ;======================================== ;DrawScreen ;192 scanlines ;now you have 192 scanlines of picture ;remember, that's 160 clocks / 3 = 53 cpu cycles ;RestoreGraphics LDA #$00 STA COLUBK ; Set Background to Black LDA #15*8 STA COLUPF LDA #1 sta CTRLPF lda #$1C sta COLUP0 lda #%00000101 sta NUSIZ0 ;end restore graphics ;paint image here LDY #0 STY HeightP0;init height to zero LDX ScanLineCount;192-6=186 because we have 6 lines of playfield to draw sta WSYNC STA HMOVE;set the sprite in motion loop sta WSYNC LDA #0 STA GRP0 CPX YPosP0 BNE SkipP0 LDY #8 STY HeightP0;if we are at the correct local, set the height ;use this to determine if we should start ;painting SkipP0 LDY HeightP0;put HeightP0 into Y for addressing BEQ FinishP0 IsP0 LDA Player_0_up-1,Y;put a line of graphics into A STA GRP0; put the line of graphics into the graphics register DEC HeightP0; to decriment so we know when to stop FinishP0;jump here if we are not painting DEX BNE loop LDA #0 STA GRP0;turn off player graphics ldx #6 Draw_Picture_loop STA WSYNC LDA Playfield_PF0-1,X STA PF0 sta PF1 sta PF2 DEX bne Draw_Picture_loop LDA #%01000010 ; Disable TIA Output STA VBLANK ;EndDrawScreen ;================================ ;================================ OverScan ;now you have 30 scanlines of overscan ;(2280 machine cycles, 6840 color clocks ;initialize graphics LDA #$00 ; put $00 in A STA WSYNC STA PF0; clear out first playfield section STA PF1; clear out second playfield section STA PF2; clear out third playfield section STA GRP0 ; clear out player graphic 0 STA GRP1 ; clear out player graphic 1 STA ENAM0 ; clear out missile 0 STA ENAM1 ; clear out missile 1 STA ENABL ; clear out ball STA COLUP0 ; set player 0 to black STA COLUP1 ; set player 1 to black STA COLUPF ; set playfield to black STA COLUBK ; set background to black ;end initialize graphics LDX #29 LDA #2 O1 STA WSYNC DEX BNE O1 ;EndOverScan ;================================== ;/////////////////////////////////////// ;go back to the beginning: ;inifinate loop JMP StartOfFrame ;////////////////////////////////////// ;***************************** ;Graphics ;***************************** Playfield_PF0 .byte #%10000001 ; .byte #%10000001 ; .byte #%01000010 ; .byte #%01000010 ; .byte #%00100100 ; .byte #%00011000 ; Player_0_up .byte #%00001000 .byte #%00011100 .byte #%00111110 .byte #%01111111 .byte #%11111110 .byte #%01111100 .byte #%00111000 .byte #%00010000 ;this is the end. change origin to the end of the 4k rom org $FFFA TheEnd .word Reset ;NMI;used in 7800? .word Reset ;RESET .word Reset ;IRQ;used in 7800? ;end of file END Quote Link to comment Share on other sites More sharing options...
Cybergoth Posted January 12, 2005 Share Posted January 12, 2005 Hi there! With a little re-arranging of your loop this'll work: loop LDA #0 CPX YPosP0 BNE SkipP0 LDY #8 STY HeightP0;if we are at the correct local, set the height ;use this to determine if we should start ;painting SkipP0 sta WSYNC STA GRP0 LDY HeightP0;put HeightP0 into Y for addressing BEQ FinishP0 IsP0 LDA Player_0_up-1,Y;put a line of graphics into A STA GRP0; put the line of graphics into the graphics register DEC HeightP0; to decriment so we know when to stop FinishP0;jump here if we are not painting DEX BNE loop The write to GRP0 was just coming too late in the first line displaying your sprite, due to the extra cycles for setting HeightP0. I think there is a lesson from Andrew regarding vertical positioning, you should definetely read that for getting a better idea of some more effective strategies for this. Greetings, Manuel Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.