Wickeycolumbus Posted March 27, 2008 Share Posted March 27, 2008 I was trying to experiment with collision detection, and it does not seem to be working. Im trying to detect the colision of the sprite and the play field. I want the sprite to start going to the left when it hits the wall. here is my code. processor 6502 include "vcs.h" org $F000 START lda #0 tax tay RAMCLR sta 0,x inx bne RAMCLR lda #%11110000 sta HMP0 lda #%00000001 sta CTRLPF lda #%00010000 sta COLUPF STARTOFFRAME lda #0 sta VBLANK lda #2 sta VSYNC sta WSYNC sta WSYNC sta WSYNC lda #0 sta VSYNC ldy #37 Verticalblank dey sta WSYNC bne Verticalblank lda #%11110000 sta COLUBK lda #%00010000 sta PF0 ldy #91 topy sta WSYNC dey bne topy ldy #9 ldx #0 Picture lda Sprite,X sta GRP0 inx dey sta WSYNC bne Picture lda #0 sta GRP0 ldy #92 topx sta WSYNC dey bne topx lda #0 sta PF0 lda #%01000010 sta VSYNC lda #0 sta COLUBK sta PF1 sta $82 sta $83 ldy #29 Overscan dey sta WSYNC bne Overscan lda CXP0FB cmp #%10000000 bne nocx sta HMCLR repeat 14 nop repend lda #%00010000 sta HMP0 sta CXCLR nocx sta WSYNC sta HMOVE dec $81 lda $81 sta $80 jmp STARTOFFRAME Sprite .byte #%00011000 .byte #%00111100 .byte #%01111110 .byte #%01110000 .byte #%01100000 .byte #%01110000 .byte #%01111110 .byte #%00111100 .byte #%00011000 org $FFFA .word START .word START .word START Quote Link to comment Share on other sites More sharing options...
SeaGtGruff Posted March 28, 2008 Share Posted March 28, 2008 (edited) It's the way you're testing the value-- "cmp #%10000000". I would have thought that would work, but after watching it in the debugger, I see that "lda CXP0FB" results in $02 if there's no collision, or $82 if there *is* a collision (between player 0 and the playfield). So you can change it to any of the following: lda CXP0FB cmp #%10000010 bne nocx lda CXP0FB AND #%10000000 beq nocx lda CXP0FB bpl nocx bit CXP0FB; <-- this is best if you ask me, A is unchanged bpl nocx; and you can test bit 6 and 7 at the same time It looks to me like the $02 is coming from the address being read-- $02-- presumably because "lda CXP0FB" is setting only bits 6 and 7, and leaving the other bits alone (?). If you change it to "lda CXP1FB" the results are $03, $43, $83, or $C3. Michael Edited March 28, 2008 by SeaGtGruff Quote Link to comment Share on other sites More sharing options...
Wickeycolumbus Posted March 28, 2008 Author Share Posted March 28, 2008 Yay! Thank you! cxsprite.bin Quote Link to comment Share on other sites More sharing options...
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