gs.c

/*
# _____     ___ ____     ___ ____
#  ____|   |    ____|   |        | |____|
# |     ___|   |____ ___|    ____| |    \    PS2DEV Open Source Project.
#-----------------------------------------------------------------------
# (c) 2009 Lion
# Licenced under Academic Free License version 2.0
# Review ps2sdk README & LICENSE files for further details.
*/

#include <kernel.h>
#include <libgs.h>

// with double buffering the DMA can be transferig data to
// the GS while you are making/calculating data for the next
// frame which speed things up. you dont have to wait on DMA to finish
// transfering data to the GS

#define	SCREEN_WIDTH			640
#define	SCREEN_HEIGHT			224	//Half-height for frame mode (frame buffer will be drawn once for each set of scan lines).

static int ScreenOffsetX, ScreenOffsetY;

#define GIF_PACKET_MAX			4

static GS_DRAWENV	draw_env[2];	// 2 display environment
static GS_DISPENV	disp_env[2];	// 2 draw	 environment

static GS_GIF_PACKET		packets[2][GIF_PACKET_MAX]; //we need 2 for double buffering
static GS_PACKET_TABLE		packet_table[2];	//we need 2 for double buffering

static int InitGraphics(void);
static void SelectDisplayContext(int context_id);
static void ClearDrawingContext(int context_id);
static int  DrawTriangles(GS_PACKET_TABLE *table, int context_index);
static void MovePoint(void);

static int active_buffer=0; // the buffer that we are currently writiing stuff to

int main(int argc, char *argv[])
{
	InitGraphics();

	packet_table[0].packet_count	= GIF_PACKET_MAX;
	packet_table[0].packets		= &packets[0][0];

	packet_table[1].packet_count	= GIF_PACKET_MAX;
	packet_table[1].packets		= &packets[1][0];

/*
	// change Background color

	draw_env[0].bg_color.b = 255;
	draw_env[0].bg_color.r = 255;
	draw_env[0].bg_color.g = 255;

	draw_env[1].bg_color.b = 255;
	draw_env[1].bg_color.r = 255;
	draw_env[1].bg_color.g = 255;
*/

	while(1)
	{
		active_buffer = GsDbGetDrawBuffer();

		GsGifPacketsClear(&packet_table[active_buffer]);	// clear the area that we are going to put the sprites/triangles/....

		MovePoint();
		DrawTriangles(&packet_table[active_buffer], active_buffer);	//add stuff to the packet area

		GsDrawSync(0);	//wait for the previous buffer to finish drawing
		GsVSync(0);

		//display the previous drawn buffer
		SelectDisplayContext(GsDbGetDisplayBuffer());	//tell CRTC which context we want to see on our tv

		// clear the draw environment before we draw stuff on it
		ClearDrawingContext(active_buffer);

		GsGifPacketsExecute(&packet_table[active_buffer], 0);	// '0' we dont have to wait because we have 2 buffers (GsDrawSync(0) will do the wait)
		GsDbSwapBuffer();
	}

	return 0;
}

static int InitGraphics(void)
{
	int env0_address, env1_address;

	GsResetGraph(GS_INIT_RESET, GS_INTERLACED, GS_MODE_NTSC, GS_FFMD_FRAME);

	//alloc 2 buffers in vram
	env0_address =  GsVramAllocFrameBuffer(SCREEN_WIDTH, SCREEN_HEIGHT, GS_PIXMODE_32);
	env1_address =  GsVramAllocFrameBuffer(SCREEN_WIDTH, SCREEN_HEIGHT, GS_PIXMODE_32);

	/*********SETUP CONTEX 1 ENVIRONMENT*************/
	GsSetDefaultDrawEnv(&draw_env[0], GS_PIXMODE_32, SCREEN_WIDTH, SCREEN_HEIGHT);
	//Retrieve screen offset parameters.
	ScreenOffsetX=draw_env[0].offset_x;
	ScreenOffsetY=draw_env[0].offset_y;
	GsSetDefaultDrawEnvAddress(&draw_env[0], env0_address);

	GsSetDefaultDisplayEnv(&disp_env[0], GS_PIXMODE_32, SCREEN_WIDTH, SCREEN_HEIGHT, 0, 0);
	GsSetDefaultDisplayEnvAddress(&disp_env[0], env1_address);

	/*********SETUP CONTEX 2 ENVIRONMENT*************/
	GsSetDefaultDrawEnv(&draw_env[1], GS_PIXMODE_32, SCREEN_WIDTH, SCREEN_HEIGHT);
	GsSetDefaultDrawEnvAddress(&draw_env[1], env1_address);

	GsSetDefaultDisplayEnv(&disp_env[1], GS_PIXMODE_32, SCREEN_WIDTH, SCREEN_HEIGHT, 0, 0);
	GsSetDefaultDisplayEnvAddress(&disp_env[1], env0_address);

	//execute draw/display environment(s)  (contex 1)
	GsPutDrawEnv1	(&draw_env[0]);
	GsPutDisplayEnv1(&disp_env[0]);

	//execute draw/display environment(s)  (contex 2)
	GsPutDrawEnv2	(&draw_env[1]);
	GsPutDisplayEnv2(&disp_env[1]);

	//set common primitive-drawing settings (Refer to documentation on PRMODE and PRMODECONT registers).
	GsOverridePrimAttributes(GS_DISABLE, 0, 0, 0, 0, 0, 0, 0, 0);

	//set transparency settings for context 1 (Refer to documentation on TEST and TEXA registers).
	GsEnableAlphaTransparency1(GS_ENABLE, GS_ALPHA_GEQUAL, 0x01, 0x00);
	GsEnableAlphaBlending1(GS_ENABLE);

	//set transparency settings for context 2 (Refer to documentation on TEST and TEXA registers).
	GsEnableAlphaTransparency2(GS_ENABLE, GS_ALPHA_GEQUAL, 0x01, 0x00);
	GsEnableAlphaBlending2(GS_ENABLE);

	return 0;
}

static void SelectDisplayContext(int context_id)
{
	// the CRTC is used to select which contex we see on our TV/VGA/HDTV

	if(context_id==0)
		GsSetCRTCSettings(CRTC_SETTINGS_DEFAULT1, 0x80);

	if(context_id==1)
		GsSetCRTCSettings(CRTC_SETTINGS_DEFAULT2, 0x80);
}

static void ClearDrawingContext(int context_id)
{
	if(context_id==0)
		GsClearDrawEnv1(&draw_env[0]);
	else
		GsClearDrawEnv2(&draw_env[1]);
}

static int point_x=100,point_y=100;
static int dir_x=0, dir_y=0;

static int DrawTriangles(GS_PACKET_TABLE *table, int context_index)
{
	QWORD	*p;

	/*	For the GIF packets in this example, the EOP flags are set to 1.
		Rightfully, it should only be set for only the final packet so that the GIF knows when it can safely switch paths,
		but to keep things simple, it's set to 1 for every packet.

		The packets are all in the PACKED format.	*/

	// top left
	//Use the uncached segment, to avoid needing to flush the data cache.
	p = (QWORD*)(UNCACHED_SEG(GsGifPacketsAlloc(table, 6)));

	gs_setGIF_TAG(((GS_GIF_TAG	*)&p[0]), 5,1,0,0,GS_GIF_PACKED,1,gif_rd_ad);
	gs_setR_PRIM(((GS_R_PRIM	*)&p[1]), GS_PRIM_TRI,0, 0, 0, 1, 0, 0, context_index, 0);
	gs_setR_RGBAQ(((GS_R_RGBAQ	*)&p[2]), 200, 100, 100, 0x80, 0.0f);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[3]), (ScreenOffsetX+0)<<4,		(ScreenOffsetY+0)<<4, 0x00000000);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[4]), (ScreenOffsetX+200)<<4,		(ScreenOffsetY+0)<<4, 0x00000000);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[5]), (ScreenOffsetX+point_x)<<4,	(ScreenOffsetY+point_y)<<4, 0x00000000);

	//top right
	//Use the uncached segment, to avoid needing to flush the data cache.
	p = (QWORD*)(UNCACHED_SEG(GsGifPacketsAlloc(table, 6)));

	gs_setGIF_TAG(((GS_GIF_TAG	*)&p[0]), 5,1,0,0,GS_GIF_PACKED,1,gif_rd_ad);
	gs_setR_PRIM(((GS_R_PRIM	*)&p[1]), GS_PRIM_TRI,0, 0, 0, 1, 0, 0, context_index, 0);
	gs_setR_RGBAQ(((GS_R_RGBAQ	*)&p[2]), 100, 200, 100, 0x80, 0.0f);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[3]), (ScreenOffsetX+SCREEN_WIDTH-200)<<4,		(ScreenOffsetY+0)<<4, 0x00000000);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[4]), (ScreenOffsetX+SCREEN_WIDTH)<<4,		(ScreenOffsetY+0)<<4, 0x00000000);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[5]), (ScreenOffsetX+point_x)<<4,				(ScreenOffsetY+point_y)<<4, 0x00000000);

	//bottom right
	//Use the uncached segment, to avoid needing to flush the data cache.
	p = (QWORD*)(UNCACHED_SEG(GsGifPacketsAlloc(table, 6)));

	gs_setGIF_TAG(((GS_GIF_TAG	*)&p[0]), 5,1,0,0,GS_GIF_PACKED,1,gif_rd_ad);
	gs_setR_PRIM(((GS_R_PRIM	*)&p[1]), GS_PRIM_TRI,0, 0, 0, 1, 0, 0, context_index, 0);
	gs_setR_RGBAQ(((GS_R_RGBAQ	*)&p[2]), 100, 100, 200, 0x80, 0.0f);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[3]), (ScreenOffsetX+SCREEN_WIDTH-200)<<4,		(ScreenOffsetY+SCREEN_HEIGHT)<<4, 0x00000000);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[4]), (ScreenOffsetX+SCREEN_WIDTH)<<4,		(ScreenOffsetY+SCREEN_HEIGHT)<<4, 0x00000000);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[5]), (ScreenOffsetX+point_x)<<4,				(ScreenOffsetY+point_y)<<4, 0x00000000);

	//bottom left
	//Use the uncached segment, to avoid needing to flush the data cache.
	p = (QWORD*)(UNCACHED_SEG(GsGifPacketsAlloc(table, 6)));

	gs_setGIF_TAG(((GS_GIF_TAG	*)&p[0]), 5,1,0,0,GS_GIF_PACKED,1,gif_rd_ad);
	gs_setR_PRIM(((GS_R_PRIM	*)&p[1]), GS_PRIM_TRI,0, 0, 0, 1, 0, 0, context_index, 0);
	gs_setR_RGBAQ(((GS_R_RGBAQ	*)&p[2]), 100, 200, 200, 0x80, 0.0f);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[3]), (ScreenOffsetX+0)<<4,		(ScreenOffsetY+SCREEN_HEIGHT)<<4, 0x00000000);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[4]), (ScreenOffsetX+200)<<4,		(ScreenOffsetY+SCREEN_HEIGHT)<<4, 0x00000000);
	gs_setR_XYZ2(((GS_R_XYZ		*)&p[5]), (ScreenOffsetX+point_x)<<4,	(ScreenOffsetY+point_y)<<4, 0x00000000);

	return 0;
}

static void MovePoint(void)
{
	if(dir_x==0)point_x -= 6;
	if(dir_x==1)point_x += 6;

	if(dir_y==0)point_y -= 8;
	if(dir_y==1)point_y += 8;

	if(point_x >SCREEN_WIDTH)
	{
		point_x= SCREEN_WIDTH;
		dir_x=0;
	}

	if(point_x <0)
	{
		point_x= 0;
		dir_x=1;
	}

	if(point_y >SCREEN_HEIGHT)
	{
		point_y= SCREEN_HEIGHT;
		dir_y=0;
	}

	if(point_y <0)
	{
		point_y= 0;
		dir_y=1;
	}
}

/*EOF*/