Rewrite start condition of line_down so that it start on exaktly the right pixel
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parent
f185c80a16
commit
4497026d95
3 changed files with 18 additions and 15 deletions
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@ -51,7 +51,7 @@
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Sub_16 >D, <D, dx, #$00
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jsr pixel_draw ;;only used first pixel. after this relative position is abused
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LDY #$00
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;LDY #$00
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LDX X_pos
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for_x:
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;; Paints A to address i btp_mem_pos* + Y
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@ -82,10 +82,9 @@ increment_y_pos:
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CPY #$08 ;
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BNE for_x
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move_8px_down: ; Z=1 --> C=1
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;; +320-8 bytes
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LDY #$00
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Add_16 >btp_mem_pos, <btp_mem_pos, #$40, #$01
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jmp for_x
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Add_16 >btp_mem_pos, <btp_mem_pos, #$40, #$01; +320
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JMP for_x
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increment_y_pos_end:
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case_2: ;; C =0 because LAG_16 so we can use !
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Add_16 >D, <D, >dy_2, <dy_2, ! ;D = D + 2*dy
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@ -6,9 +6,9 @@
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X_pos_ = $0E
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Y_end_ = $10
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X_end_ = $11
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LDA #$d0
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LDA #$d2
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STA X_pos_
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LDA #$60
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LDA #$62
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STA Y_pos_
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LDA #$ff
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STA X_end
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@ -47,14 +47,18 @@ end__:
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LDA #%00000111 ; A = y (mod 8)
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AND Y_pos ;; offset to add
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;;ading offset, same as psudocode bellow
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;;Add_16 >btp_mem_pos, <btp_mem_pos, A, #$00
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CLC ; Y = b_low
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ADC >btp_mem_pos
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STA >btp_mem_pos
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LDA #$00
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ADC <btp_mem_pos ; C =0
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STA <btp_mem_pos
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;CLC ; Y = b_low
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;ADC >btp_mem_pos
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;STA >btp_mem_pos
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;LDA #$00
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;ADC <btp_mem_pos ; C =0
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;STA <btp_mem_pos
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TAY
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CLC
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LDA #$00
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STA $4B
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@ -87,9 +91,9 @@ end__:
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Add_16 >btp_mem_pos, <btp_mem_pos, #<Bitmap, #>Bitmap, !
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;;Let draw some stuff
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LDX #$00
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;LDY #$00
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LDA byte_to_paint ;; note that both bytes are used!
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ORA (>btp_mem_pos, X)
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STA (>btp_mem_pos, X)
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ORA (>btp_mem_pos), Y
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STA (>btp_mem_pos), Y
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RTS
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.endproc
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