git.y1.nz

commit 2a8675de7eb3a0ee513dcbc8cc2d9fe4f32535b0
parent 343687c4a94df73e02dcd44a604d84775ff39655
Author: Toxa <untoxa@mail.ru>
Date:   Mon, 15 Feb 2021 18:12:13 +0300

fix line drawing for line(50,50,23,22);

Diffstat:
M
gbdk-lib/examples/gb/filltest/filltest.c
11
+++++++++++
M
gbdk-lib/libc/gb/drawing.s
27
+++++++++++++++++++--------

2 files changed, 30 insertions(+), 8 deletions(-)
diff --git a/gbdk-lib/examples/gb/filltest/filltest.c b/gbdk-lib/examples/gb/filltest/filltest.c
@@ -4,6 +4,14 @@
 #include <gb/gb.h>
 #include <gb/drawing.h>
 
+void linetest(UBYTE x, UBYTE y, UBYTE w) {
+    color(DKGREY,WHITE,SOLID);
+	for (int i = -w; i <= w; i++) line(x,y,x+i,y-w);
+	for (int i = -w; i <= w; i++) line(x,y,x+w,y+i);
+	for (int i = -w; i <= w; i++) line(x,y,x+i,y+w);
+	for (int i = -w; i <= w; i++) line(x,y,x-w,y+i);	
+}
+
 void main(void)
 {
     UBYTE  a,b,c,d,e;
@@ -34,6 +42,9 @@ void main(void)
     box(0,130,40,143,M_NOFILL);
     box(50,130,90,143,M_FILL);
 
+
+	linetest(130, 100, 20);
+
     /* Scroll the screen using the hardest method imaginable :) */
     for (c=0; c<=143; c++) {
 	for (b=0; b<=142; b++) {
diff --git a/gbdk-lib/libc/gb/drawing.s b/gbdk-lib/libc/gb/drawing.s
@@ -33,6 +33,7 @@
 	.area   _DRAW_HEADER (ABS)
 
 	.org	0x70
+.drawing_bits_tbl::
 	.byte	0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01
 	.byte	0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80
 
@@ -704,6 +705,7 @@ swap$:
 	JR	NC,s1$
 	CPL
 	INC	A
+
 s1$:	LD	(.delta_y),A
 	LD	H,A
 
@@ -712,6 +714,7 @@ s1$:	LD	(.delta_y),A
 	JR	NC,s2$
 	CPL
 	INC	A
+
 s2$:	LD	(.delta_x),A
 
 	SUB	H
@@ -823,7 +826,7 @@ dx1$:
 
 	LD	A,B
 	AND	#7
-	ADD	#0x70	; Table of bits is located at 0x0070
+	ADD	#<.drawing_bits_tbl	; Table of bits is located at 0x0070
 	LD	C,A
 	LD	B,#0x00
 	LD	A,(BC)	; Get start bit
@@ -934,7 +937,7 @@ nadj$:
 	AND	#7	;just look at bottom 3 bits
 	JR	Z,2$
 	PUSH	HL
-	ADD	#0x70	;Table of bits is located at 0x0070
+	ADD	#<.drawing_bits_tbl	;Table of bits is located at 0x0070
 	LD	L,A
 	LD	H,#0x00
 	LD	C,(HL)
@@ -1014,8 +1017,16 @@ y2$:
 	SUB	E
 	JR	Z,y2a$
 	LD	A,#0x00
-	JR	NC,y2a$
-	LD	A,#0xFF
+	
+;	JR	NC,y2a$	; old code; fix draw to up-left below
+;	LD	A,#0xFF 
+
+	LD	L,A	; invert delta if x1 less than x2
+	LD	A,B
+	SUB	D
+	LD	A,L
+	JR	C,y2a$
+	CPL
 
 y2a$:
 	LD	B,D
@@ -1113,7 +1124,7 @@ dy1$:
 
 	LD	A,B
 	AND	#7
-	ADD	#0x70	; Table of bits is located at 0x0070
+	ADD	#<.drawing_bits_tbl	; Table of bits is located at 0x0070
 	LD	C,A
 	LD	B,#0x00
 	LD	A,(BC)	; Get start bit
@@ -1190,7 +1201,7 @@ nchgy$:
 	LD	A,B	;check X
 	AND	#7	;just look at bottom 3 bits
 	PUSH	HL
-	ADD	#0x70	;Table of bits is located at 0x0070
+	ADD	#<.drawing_bits_tbl	;Table of bits is located at 0x0070
 	LD	L,A
 	LD	H,#0x00
 	LD	A,(HL)	;Get mask bit
@@ -1233,7 +1244,7 @@ nchgy$:
 	LD	A,B
 
 	AND     #7
-	ADD     #0x70		; Table of bits is located at 0x0070
+	ADD     #<.drawing_bits_tbl		; Table of bits is located at 0x0070
 	LD      C,A
 	LD      B,#0x00
 	LD      A,(BC)
@@ -1412,7 +1423,7 @@ nchgy$:
 	LD	A,B
 
 	AND     #7
-	ADD     #0x70		; Table of bits is located at 0x0070
+	ADD     #<.drawing_bits_tbl		; Table of bits is located at 0x0070
 	LD      C,A
 	LD      B,#0x00
 	LD      A,(BC)

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