From fe22fe089508be9cdad9847e89802bc2c0cffb6a Mon Sep 17 00:00:00 2001
From: DaniTheSkunk <>
Date: Tue, 24 Jan 2023 11:45:52 +0000
Subject: [PATCH] added color mixing and gsa loop stacking

---
 examples/gsa_simple.c | 26 ++++++++++++++++++++++++--
 include/color32.h     |  5 +++++
 include/gsa.h         |  5 +++++
 src/color32.c         | 12 ++++++++++++
 src/gsa.c             | 35 ++++++++++++++++++++++++++++++++---
 5 files changed, 78 insertions(+), 5 deletions(-)

diff --git a/examples/gsa_simple.c b/examples/gsa_simple.c
index 1aa2f27..e850ad3 100644
--- a/examples/gsa_simple.c
+++ b/examples/gsa_simple.c
@@ -1,12 +1,26 @@
+#include "color32.h"
 #include "gamepad.h"
 #include "gsa_map.h"
 #include "gsa_text.h"
 #include <gsa.h>
 
-void init() {
+sw_color32 pal[GSA_PALETTE_SIZE];
 
+void fade_palette(f32 amount) {
+	i32 i;
+
+	for(i = 0; i < GSA_PALETTE_SIZE; ++i) {
+		palette[i] = sw_color32_mix(SW_COLOR32_BLACK, pal[i], amount);
+	}
+}
+
+bool tick_fade_in();
+
+void init() {
 	i32 x, y;
 
+	gsa_copy_palette_to(pal);
+
 	for(y = 0; y < 11; ++y) {
 		for(x = 0; x < 19; ++x) {
 			maps[0].tiles[x][y] = 0x1000;
@@ -28,10 +42,18 @@ void init() {
 	maps[1].half_tile = true;
 	font = 0x1010;
 	gsa_write_text(1, 7, 3, "Game Skunk Advance!!! <3");
-	gsa_map_clear(0);
+	gsa_run_loop(tick_fade_in);
 }
 
 void tick() {
 	maps[0].scrollx -= input.x_dir;
 	maps[0].scrolly -= input.y_dir;
 }
+
+bool tick_fade_in() {
+	static i32 t = 0;
+
+	fade_palette(t / 60.f);
+	++t;
+	return t <= 60;
+}
diff --git a/include/color32.h b/include/color32.h
index de1fdf7..cb9c13e 100644
--- a/include/color32.h
+++ b/include/color32.h
@@ -5,6 +5,9 @@
 
 typedef u32 sw_color32;
 
+#define SW_COLOR32_BLACK 0xFF000000
+#define SW_COLOR32_WHITE 0xFFFFFFFF
+
 sw_color32 sw_color32_from_rgb(u8 r, u8 g, u8 b);
 sw_color32 sw_color32_from_rgba(u8 r, u8 g, u8 b, u8 a);
 
@@ -18,4 +21,6 @@ f32 sw_color32_get_gf(sw_color32 col);
 f32 sw_color32_get_bf(sw_color32 col);
 f32 sw_color32_get_af(sw_color32 col);
 
+sw_color32 sw_color32_mix(sw_color32 a, sw_color32 b, f32 mix);
+
 #endif /* GUARD_99E25E7F8183EF0D8D27390EBC173C04 */
diff --git a/include/gsa.h b/include/gsa.h
index 7ed05e4..698910e 100644
--- a/include/gsa.h
+++ b/include/gsa.h
@@ -29,6 +29,7 @@
 #include "window.h"
 
 #define MAX_SPRITES 256
+#define GSA_PALETTE_SIZE 256
 
 struct gsa_sprite {
 	u16 tile;
@@ -37,8 +38,12 @@ struct gsa_sprite {
 
 extern struct gsa_sprite sprites[MAX_SPRITES];
 extern struct sw_image8 *_gfx;
+extern sw_color32 palette[GSA_PALETTE_SIZE];
 
 int gsa_main(int argc, char *argv[]);
+void gsa_copy_palette_to(sw_color32 *dst);
+void gsa_copy_palette_from(sw_color32 *src);
+void gsa_run_loop(bool (*loopfun)());
 
 /* to be implemented in game */
 
diff --git a/src/color32.c b/src/color32.c
index 05633bf..4de9ca9 100644
--- a/src/color32.c
+++ b/src/color32.c
@@ -39,3 +39,15 @@ f32 sw_color32_get_bf(sw_color32 col) {
 f32 sw_color32_get_af(sw_color32 col) {
 	return (f32)sw_color32_get_a(col) / 255.f;
 }
+
+sw_color32 sw_color32_mix(sw_color32 a, sw_color32 b, f32 mix) {
+	f32 imix;
+	imix = 1.f - mix;
+
+	return sw_color32_from_rgba(
+	    sw_color32_get_r(a) * imix + sw_color32_get_r(b) * mix,
+	    sw_color32_get_g(a) * imix + sw_color32_get_g(b) * mix,
+	    sw_color32_get_b(a) * imix + sw_color32_get_b(b) * mix,
+	    sw_color32_get_a(a) * imix + sw_color32_get_a(b) * mix
+	);
+}
diff --git a/src/gsa.c b/src/gsa.c
index 4c33a54..7f2a6bd 100644
--- a/src/gsa.c
+++ b/src/gsa.c
@@ -52,10 +52,15 @@ struct render_vert {
 
 static i32 next_render_vert;
 static struct render_vert render_verts[MAX_RENDER_VERTS * 4];
-static sw_color32 palette[256];
+sw_color32 palette[GSA_PALETTE_SIZE];
 static f32 palette_gl[1024];
 static u32 tex;
 
+#define GSA_LOOP_STACK_SIZE 16
+
+static bool (*loop_stack[GSA_LOOP_STACK_SIZE])();
+static i8 loop_stack_i;
+
 int gsa_main(int argc, char *argv[]) {
 	(void)argc;
 	(void)argv;
@@ -63,6 +68,9 @@ int gsa_main(int argc, char *argv[]) {
 
 	sw_log("Initialising GameSkunkAdvance v0.0");
 
+	memset(loop_stack, 0, sizeof(loop_stack));
+	loop_stack_i = -1;
+
 	_win = sw_window_create(sw_vec2i(304, 176), "Game Skunk Advance v0.0");
 	program = sw_shaderprogram_create(vert_source, frag_source);
 
@@ -70,7 +78,6 @@ int gsa_main(int argc, char *argv[]) {
 	sw_log("GL_MAX_VERTEX_UNIFORM_COMPONENTS: %i", max_components);
 
 	memcpy(palette, _gfx->palette, sizeof(_gfx->palette));
-	sw_debug("%08X", _gfx->palette[1]);
 	glGenTextures(1, &tex);
 	glBindTexture(GL_TEXTURE_2D, tex);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
@@ -122,6 +129,22 @@ int gsa_main(int argc, char *argv[]) {
 	return 0;
 }
 
+void gsa_copy_palette_to(sw_color32 *dst) {
+	memcpy(dst, palette, sizeof(palette));
+}
+
+void gsa_copy_palette_from(sw_color32 *src) {
+	memcpy(palette, src, sizeof(palette));
+}
+
+void gsa_run_loop(bool (*loopfun)()) {
+	++loop_stack_i;
+	if(loop_stack_i >= GSA_LOOP_STACK_SIZE) {
+		sw_error("exceeded loop stack size");
+	}
+	loop_stack[loop_stack_i] = loopfun;
+}
+
 static void add_render_vert(f32 x, f32 y, f32 tx, f32 ty) {
 	render_verts[next_render_vert].x = x;
 	render_verts[next_render_vert].y = y;
@@ -169,7 +192,13 @@ void _gsa_tick() {
 
 	_gsa_input_tick();
 
-	tick();
+	if(loop_stack_i == -1) {
+		tick();
+	} else {
+		if(!loop_stack[loop_stack_i]()) {
+			--loop_stack_i;
+		}
+	}
 
 	next_render_vert = 0;