draw 1/2 of circle by circle-help-subroutine

wip-hugo/routines/circle/circle.inc

@@ -9,5 +9,9 @@
         Y_rel = $E3
         temp = $E4
         temp_ = $E7
-        btp_mem_pos_center = $E5 ;; 16bit <fix>
+        ; E8 - EA is used by pixel.inc
-        btp_mem_pos_inv = $EE    ;; 16bit <fix>
+        btp_mem_pos_center = $E5 ; 16bit value (uses E6)
+        btp_mem_pos_center_two = btp_mem_pos_center
+        btp_mem_pos_inv_y =$EB   ; 16bit value (uses EC)
+        Y_inv_x = $EC
+        btp_mem_pos_inv = $EE    ; 16bit value (uses EF)

wip-hugo/routines/circle/circle.s

@@ -3,7 +3,7 @@
 .proc circle
         .include "circle.inc"
         ;; We use the algorithm jerkos method
-        ;; https://schwarzers.com/algorithms/
+        ;; git
 
         ;; X_rel = radius (share the same address)
 
@@ -27,8 +27,9 @@ draw_center_px_in_circle:
         LDA btp_mem_pos + 1
         STA btp_mem_pos_center + 1
         ;; btp_mem_pos_center_two = 2*btp_mem_pos_center | used later for calculating btp_mem_pos_inv
-        btp_mem_pos_center_two = btp_mem_pos_center
         Mult_16 btp_mem_pos_center, btp_mem_pos_center + 1
+        ;; fix offset of 8 bytes, idk why this is needed
+        Sub_16 btp_mem_pos_center, btp_mem_pos_center + 1, #$40, #$01 ;-320
 
 
 draw_right_px_in_circle:
@@ -41,44 +42,19 @@ draw_right_px_in_circle:
         JSR pixel_draw
         ;; This sets byte_to_paint, btp_mem_pos and Y
 
+        LDA btp_mem_pos
+        STA btp_mem_pos_inv_y
+        LDA btp_mem_pos + 1
+        STA btp_mem_pos_inv_y + 1
+
+        ;; fix offset of 8 bytes, idk why this is needed
+        Sub_16 btp_mem_pos_inv_y, btp_mem_pos_inv_y + 1, #$40, #$01 ;-320
+
+
         SEC ;; See draw_pixel_inv
 while_x_bigger_then_y:
-
+        ;;Draw pixels
-
+        JSR circle_help
-draw_pixel:
-        LDA byte_to_paint ;A byte containing a single 1. Coresponds to X position in the chunk.
-        ORA (btp_mem_pos), Y
-        STA (btp_mem_pos), Y
-
-draw_pixel_inv:
-        ;;C = 1 beacause the branching to while_x_bigger_then_y and SEC on first ittteration.
-        LDA btp_mem_pos_center_two
-        SBC btp_mem_pos
-        STA btp_mem_pos_inv
-        LDA btp_mem_pos_center_two + 1
-        SBC btp_mem_pos + 1
-        STA btp_mem_pos_inv + 1
-
-        ;; calculate the inverted y value Y = 7-Y
-        STY temp
-        LDA #$07
-        ;; C = 1 because arithmatic above
-        SBC temp
-        TAY
-
-;; calculate byte_to_paint_inv 00000001 --> 10000000, 00000010 --> 01000000 ... etc
-;; uses a table!
-        STX temp_
-        LDX byte_to_paint
-	LDA inverse_factor_value, X;; (see END.s)
-	LDX temp_
-
-	; A = byte_to_paint_inv
-        ORA (btp_mem_pos_inv), Y
-        STA (btp_mem_pos_inv), Y
-
-        ;;Recover the Y value (we changed it because evrything is inverted)
-        LDY temp
 
 increment_y_pos:
         INC Y_rel ; y++
@@ -87,9 +63,10 @@ increment_y_pos:
 move_8px_down:
         LDY #$07
         ;; Switch to chunk bellow
-        ; So we subtract  #$4001
+        ; So we subtract  #$0140
         ; C = 1 because branching!
         Sub_16 btp_mem_pos, btp_mem_pos + 1, #$40, #$01, ! ;-320
+        Add_16 btp_mem_pos_inv_y, btp_mem_pos_inv_y + 1, #$40, #$01 ;+320
 increment_y_pos_end:
 
         ;;t1 += y
@@ -115,6 +92,7 @@ move_8px_left:
         ;; -8.
         ;; C = 1 because branching
         Sub_16 btp_mem_pos, btp_mem_pos + 1, #$08, #$00, !
+        Sub_16 btp_mem_pos_inv_y, btp_mem_pos_inv_y + 1, #$08, #$00, !
         ;; Restores byte to paint
         LDA #%00000001
         STA byte_to_paint
@@ -128,4 +106,5 @@ endif:
 
         BCS while_x_bigger_then_y
         RTS
+        .include "routines/circle/circle_help.s"
 .endproc

wip-hugo/routines/circle/circle_help.s

@@ -0,0 +1,87 @@
+.proc circle_help ;; This is because jmp cant jump that long!
+.include "circle.inc"
+
+
+;;We have named the parts of the circle as such.
+;;               |
+;;      q22      |      q12
+;;               |
+;;   q21         |         q11
+;;---------------X-----------------> X
+;;   q31         |         q41
+;;               |
+;;      q32      |      q42
+;;               |
+;;               v Y
+;; The q stands for quarter, whe have 4 quarter, and each quarter is split into 2
+
+
+draw_pixel:;;q11
+        LDA byte_to_paint ;A byte containing a single 1. Coresponds to X position in the chunk.
+        ORA (btp_mem_pos), Y
+        STA (btp_mem_pos), Y
+
+draw_pixel_inv_y:;;q41
+        STY temp
+        LDA #$07
+        SEC
+        SBC temp
+        TAY
+        LDA byte_to_paint
+        ORA (btp_mem_pos_inv_y), Y
+        STA (btp_mem_pos_inv_y), Y
+        ;hihi:
+        ;jmp hihi
+        LDY temp
+
+draw_pixel_inv_y_mirror:
+        SEC
+        LDA btp_mem_pos_center_two
+        SBC btp_mem_pos_inv_y
+        STA btp_mem_pos_inv
+        LDA btp_mem_pos_center_two + 1
+        SBC btp_mem_pos_inv_y + 1
+        STA btp_mem_pos_inv + 1
+
+        STX temp_
+        LDX byte_to_paint
+	LDA inverse_factor_value, X;; (see END.s)
+	LDX temp_
+
+	; A = byte_to_paint_inv
+        ORA (btp_mem_pos_inv), Y
+        STA (btp_mem_pos_inv), Y
+
+
+draw_pixel_mirror:;;q31
+        SEC
+        ;;C = 1 beacause the branching to while_x_bigger_then_y and SEC on first ittteration.
+        LDA btp_mem_pos_center_two
+        SBC btp_mem_pos
+        STA btp_mem_pos_inv
+        LDA btp_mem_pos_center_two + 1
+        SBC btp_mem_pos + 1
+        STA btp_mem_pos_inv + 1
+
+        ;; calculate the inverted y value Y = 7-Y
+        STY temp
+        LDA #$07
+        ;; C = 1 because arithmatic above
+        SBC temp
+        TAY
+
+        ;; calculate byte_to_paint_inv 00000001 --> 10000000, 00000010 --> 01000000 ... etc
+        ;; uses a table!
+        STX temp_
+        LDX byte_to_paint
+	LDA inverse_factor_value, X;; (see END.s)
+	LDX temp_
+
+	; A = byte_to_paint_inv
+        ORA (btp_mem_pos_inv), Y
+        STA (btp_mem_pos_inv), Y
+
+        ;;Recover the Y value (we changed it because evrything is inverted)
+        LDY temp
+        RTS
+.endproc