Added movement and sprite rotation.. you can now actually drive the car along.

gba/cartest/src/cartest.c

@@ -23,7 +23,10 @@
 // storage space for palette data
 //---------------------------------------------------------------------------------
 u16 PaletteBuffer[256];
-OBJATTR car;
+
+// 4 sprites and one
+OBJATTR oe_buffer[4];
+OBJAFFINE *const oa_buffer = (OBJAFFINE*)oe_buffer;
 
 unsigned int frame;
 
@@ -41,6 +44,9 @@ void VblankInterrupt()
 int main(void)
 //---------------------------------------------------------------------------------
 {
+	OBJATTR*car = &oe_buffer[0];
+	OBJAFFINE*car_aff = &oa_buffer[0];
+
 	// Set up the interrupt handlers
 	InitInterrupt();
 
@@ -55,36 +61,96 @@ int main(void)
 	// screen mode, background and objects to display
        	SetMode( MODE_4 | BG2_ON | OBJ_ON | OBJ_1D_MAP );
 
-	u32 white = 0x10101010; CpuFastSet(&white, (void*)VRAM, FILL | 240*160/4);
+	u32 white = 0x10101010; 
+	CpuFastSet(&white, (void*)VRAM, FILL | 240*160/4);
        	FadeToPalette((void*)car_pal_bin, 1);
 
 	CpuFastSet(car_bin, BITMAP_OBJ_BASE_ADR, COPY32 | car_bin_size/4);
        	CpuFastSet(car_pal_bin, OBJ_COLORS, COPY32 | car_pal_bin_size/4);
 
-	memset(&car, 0, sizeof(car));
+	//	u32 nothing = 0; 
-	car.attr2 = OBJ_CHAR(512);
+	//	CpuFastSet(&nothing, (void*)oe_buffer, FILL | sizeof(oe_buffer)/4);
-	car.attr1 = OBJ_SIZE(1) | OBJ_X(100);
+	//	memset(oe_buffer, 0, sizeof(oe_buffer));
-	car.attr0 = OBJ_256_COLOR | OBJ_Y(49);
+	car->attr2 = OBJ_CHAR(512);
+	//	car->attr1 = OBJ_SIZE(1) | OBJ_X(100);
+	//	car->attr0 = OBJ_256_COLOR | OBJ_ROT_SCALE_ON | OBJ_Y(49);
+
+	s32 base = (s32)(0.707106781 * 256);
+	s32 one = 1 << 8;
+
+	car_aff->pa = 1 << 8;
+	car_aff->pb = 0;
+	car_aff->pc = 0;;
+	car_aff->pd = 1 << 8;
+
+	int x = 112;
+	int y = 72;
 
 	while (1) {
+		int xadjust = 0;
+		int yadjust = 0;
+
+		// This isn't very tidy, but a cleanup is always
+		// imminent...
+
+		if ((KeysHeld() & KEY_RIGHT) && (KeysHeld() & KEY_UP)) {
+		  car_aff->pa = base;
+		  car_aff->pb = base;
+		  car_aff->pc = -base;
+		  car_aff->pd = base;
+		} else if ((KeysHeld() & KEY_RIGHT) && (KeysHeld() & KEY_DOWN)) {
+		  car_aff->pa = -base;
+		  car_aff->pb = base;
+		  car_aff->pc = -base;
+		  car_aff->pd = -base;
+		} else if ((KeysHeld() & KEY_LEFT) && (KeysHeld() & KEY_DOWN)) {
+		  car_aff->pa = -base;
+		  car_aff->pb = -base;
+		  car_aff->pc = base;
+		  car_aff->pd = -base;
+		} else if ((KeysHeld() & KEY_LEFT) && (KeysHeld() & KEY_UP)) {
+		  car_aff->pa = base;
+		  car_aff->pb = -base;
+		  car_aff->pc = base;
+		  car_aff->pd = base;
+		} else if (KeysHeld() & KEY_UP) {
+		  car_aff->pa = 1 << 8;
+		  car_aff->pb = 0;
+		  car_aff->pc = 0;;
+		  car_aff->pd = 1 << 8;
+		} else if (KeysHeld() & KEY_RIGHT) {
+		  car_aff->pa = 0;
+		  car_aff->pb = one;
+		  car_aff->pc = -one;
+		  car_aff->pd = 0;
+		} else if (KeysHeld() & KEY_DOWN) {
+		  car_aff->pa = -one;
+		  car_aff->pb = 0;
+		  car_aff->pc = 0;
+		  car_aff->pd = -one;
+		} else if (KeysHeld() & KEY_LEFT) {
+		  car_aff->pa = 0;
+		  car_aff->pb = -one;
+		  car_aff->pc = one;
+		  car_aff->pd = 0;
+		}
+
 		if (KeysHeld() & KEY_RIGHT)
-		  car.attr1 = OBJ_SIZE(1) | OBJ_X(172);
+		  x += 1;
 		else if (KeysHeld() & KEY_LEFT)
-		  car.attr1 = OBJ_SIZE(1) | OBJ_X(52);
+		  x -= 1;
-		else
-		  car.attr1 = OBJ_SIZE(1) | OBJ_X(112);
 
 		if (KeysHeld() & KEY_UP)
-		  car.attr0 = OBJ_256_COLOR | OBJ_Y(32);
+		  y -= 1;
 		else if (KeysHeld() & KEY_DOWN)
-		  car.attr0 = OBJ_256_COLOR | OBJ_Y(112);
+		  y += 1;
-		else
+
-		  car.attr0 = OBJ_256_COLOR | OBJ_Y(72);
+		car->attr1 = OBJ_SIZE(1) | OBJ_X(x+xadjust);
+		car->attr0 = OBJ_256_COLOR | OBJ_DOUBLE | OBJ_ROT_SCALE_ON | OBJ_Y(y+yadjust);
 
 	  	VBlankIntrWait();
-		CpuFastSet(&car, OAM, COPY32 | sizeof(car)/4);
+		CpuFastSet(oa_buffer, OAM, COPY32 | sizeof(OBJAFFINE)/4);
 	}
-
 }