From 54e1768affa53cfee61ac5e1dce2ce1004662ec8 Mon Sep 17 00:00:00 2001
From: Vince Weaver <vince@deater.net>
Date: Wed, 18 Sep 2024 22:25:58 -0400
Subject: [PATCH] climb: add rock collision

---
 games/peasant_mini/cliff/climb.s | 173 +++++++++++++++++++++++++++++++
 1 file changed, 173 insertions(+)

diff --git a/games/peasant_mini/cliff/climb.s b/games/peasant_mini/cliff/climb.s
index d8c28c41..5950ff35 100644
--- a/games/peasant_mini/cliff/climb.s
+++ b/games/peasant_mini/cliff/climb.s
@@ -316,9 +316,27 @@ move_bird_done:
 
 	ldx	#0
 	stx	CURRENT_ROCK
+
 move_rock_loop:
+
 	ldx	CURRENT_ROCK
 
+	lda	PEASANT_FALLING
+	bne	no_rock_collision
+
+	; collision detect
+
+	jsr	rock_collide
+	bcc	no_rock_collision
+
+	; collision happened!
+
+	lda	#1
+	sta	PEASANT_FALLING
+
+no_rock_collision:
+
+
 	lda	rock_state,X
 	beq	move_rock_normal
 	cmp	#3
@@ -833,3 +851,158 @@ bird_no_collide:
 	clc
 	rts
 
+
+
+
+	;===========================
+	; check for rock collisions
+	;===========================
+	; which rock in X
+
+rock_collide:
+
+	; 0 = bit, 1 = little
+	lda	rock_type,X
+	bne	little_rock_collide
+
+
+	;===========================
+	; big rock collide
+
+big_rock_collide:
+
+	; big rock is 3x22
+	; little rock is 2x14
+	; peasant is 3x30
+
+	; doing a sort of Minkowski Sum collision detection here
+	; with the rectangular regions
+
+	; might be faster to set it up so you can subtract, but that leads
+	;	to issues when we go negative and bcc/bcs are unsigned compares
+
+	; if (rock_x+1<PEASANT_X-1) no_collide
+	;	equivalent, if (rock_x+2<PEASANT_X)
+	;	equivalent, if (PEASANT_X-1 >= rock_x+1)
+
+	lda	rock_x,X
+	sta	TEMP_CENTER
+	inc	TEMP_CENTER	; rock_x+1
+
+	sec
+	lda	PEASANT_X
+	sbc	#1			; A is PEASANT_X-1
+	cmp	TEMP_CENTER		; compare with rock_x+1
+	bcs	rock_no_collide		; bge
+
+	; if (rock_x+1>=PEASANT_X+3) no collide
+	;	equivalent, if (rock_x-2>=PEASANT_X)
+	;	equivalent, if (PEASANT_X+3<rock_x+1)
+
+	; carry clear here
+	adc	#4			; A is now PEASANT_X+3
+	cmp	TEMP_CENTER
+	bcc	rock_no_collide		; blt
+
+	; bird = 16
+	; rock = 22
+
+	; if (rock_y+11<PEASANT_Y-11) no_collide
+	;	equivalent, if (rock_y+22<PEASANT_Y)
+	;	equivalent, if (PEASANT_Y-11>=rock_y+11)
+
+	lda	rock_y,X
+	clc
+	adc	#11
+	sta	TEMP_CENTER
+
+	lda	PEASANT_Y
+	sec
+	sbc	#11			; A is now PEASANT_Y-11
+	cmp	TEMP_CENTER
+	bcs	rock_no_collide		; blt
+
+	; if (rock_Y+11>=PEASANT_Y+41) no collide
+	;	equivalent, if (rock_y-30>=PEASANT_Y)
+	;	equivalent, if (PEASANT_Y+41<rock_y+11)
+
+	; carry clear here
+	adc	#41			; A is now bird_y+30
+	cmp	TEMP_CENTER
+	bcc	rock_no_collide		; blt
+
+rock_yes_collide:
+	sec
+	rts
+
+rock_no_collide:
+	clc
+	rts
+
+	;=================================
+	; little rock collision
+	; Arkansas here we come
+
+little_rock_collide:
+
+	; little rock is 2x14
+	; peasant is 3x30
+
+	; doing a sort of Minkowski Sum collision detection here
+	; with the rectangular regions
+
+	; if (PEASANT_X >= rock_x+2) no collide
+
+	;      rr
+	;        ppp
+
+	lda	rock_x,X
+	sta	TEMP_CENTER
+	inc	TEMP_CENTER	; rock_x+1
+	inc	TEMP_CENTER	; rock_x+2
+
+	sec
+	lda	PEASANT_X		; A is PEASANT_X
+	cmp	TEMP_CENTER		; compare with rock_x+1
+	bcs	rock_no_collide		; bge
+
+
+	;	if (PEASANT_X+3<rock_x)
+	;	if (PEASANT_X+5<rock_x+2)
+
+	;       rrzz
+	;    pppzz
+
+	; carry clear here
+	adc	#5			; A is now PEASANT_X+5
+	cmp	TEMP_CENTER		; rock_x+2
+	bcc	rock_no_collide		; blt
+
+	; bird = 16
+	; big rock = 22
+	; little rock = 14
+
+	; if (rock_y+7<PEASANT_Y-7) no_collide
+	;	equivalent, if (rock_y+14<PEASANT_Y)
+	;	equivalent, if (PEASANT_Y-7>=rock_y+7)
+
+	lda	rock_y,X
+	clc
+	adc	#7
+	sta	TEMP_CENTER
+
+	lda	PEASANT_Y
+	sec
+	sbc	#7			; A is now PEASANT_Y-7
+	cmp	TEMP_CENTER
+	bcs	rock_no_collide		; blt
+
+	; if (rock_Y+7>=PEASANT_Y+37) no collide
+	;	equivalent, if (rock_y-30>=PEASANT_Y)
+	;	equivalent, if (PEASANT_Y+37<rock_y+7)
+
+	; carry clear here
+	adc	#27			; A is now bird_y+30
+	cmp	TEMP_CENTER
+	bcc	rock_no_collide		; blt
+	bcs	rock_yes_collide	; bra