Simplified controls, so that strafe left/right only moves on the X/Y plane, while up/down only moves along the Z axis.

input.c

@@ -67,30 +67,24 @@ void input_process()
 	if (!(buttons & PAD_TRIANGLE))
 	{
 		// Move up (+Z)
-		cam_pos.vx += (cam_mtx.m[0][2] * moveInterval) >> 12;
-		cam_pos.vy += (cam_mtx.m[1][2] * moveInterval) >> 12;
-		cam_pos.vz += (cam_mtx.m[2][2] * moveInterval) >> 12;
+		cam_pos.vz += moveInterval;
 	}
 	if (!(buttons & PAD_CROSS))
 	{
 		// Move down (-Z)
-		cam_pos.vx -= (cam_mtx.m[0][2] * moveInterval) >> 12;
-		cam_pos.vy -= (cam_mtx.m[1][2] * moveInterval) >> 12;
-		cam_pos.vz -= (cam_mtx.m[2][2] * moveInterval) >> 12;
+		cam_pos.vz -= moveInterval;
 	}
 	if (!(buttons & PAD_L1))
 	{
 		// Strafe left (-X)
 		cam_pos.vx -= (cam_mtx.m[0][0] * moveInterval) >> 12;
 		cam_pos.vy -= (cam_mtx.m[1][0] * moveInterval) >> 12;
-		cam_pos.vz -= (cam_mtx.m[2][0] * moveInterval) >> 12;
 	}
 	if (!(buttons & PAD_R1))
 	{
 		// Strafe right (+X)
 		cam_pos.vx += (cam_mtx.m[0][0] * moveInterval) >> 12;
 		cam_pos.vy += (cam_mtx.m[1][0] * moveInterval) >> 12;
-		cam_pos.vz += (cam_mtx.m[2][0] * moveInterval) >> 12;
 	}
 	if (!(buttons & PAD_L2))
 	{
@@ -152,7 +146,6 @@ void input_process()
 		// Strafe left/right
 		cam_pos.vx += (cam_mtx.m[0][0] * leftJoyX * moveInterval) >> 19;
 		cam_pos.vy += (cam_mtx.m[1][0] * leftJoyX * moveInterval) >> 19;
-		cam_pos.vz += (cam_mtx.m[2][0] * leftJoyX * moveInterval) >> 19;
 
 		// Rotate left/right
 		cam_rot.vz -= (rightJoyX * rotInterval) >> 7;