161 lines
7.6 KiB
HTML
161 lines
7.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<title>Move actions</title>
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<link href="style.css" rel="stylesheet" type="text/css">
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</head>
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<body background="images/back.gif">
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<!--START-->
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<h3>Move actions</h3>
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The first set of actions consists of those related to movement of objects.
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The following actions exist:
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<p>
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<b><img src="images/action_move1.bmp"> Move Fixed</b><br>
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Use this action to start the instance moving in a particular direction.
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You can indicate the direction using the buttons with the arrows on it.
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Use the middle button to stop the motion. Also you need to specify
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the speed of the motion. This speed is given in pixels per step.
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Preferably don't use negative speeds.
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You can specify multiple directions. In this case a random choice is made.
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In this way you can let a monster start moving either left or right.
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<p>
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<b><img src="images/action_move2.bmp"> Move Free</b><br>
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This is the second way to specify a motion. Here you can indicate a precise direction.
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This is an angle between 0 and 360 degrees. 0 means to the right.
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The direction is counter-clockwise. So for example 90 indicates an
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upward direction. If you want an arbitrary direction, you can type
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<tt>random(360)</tt>. As you will see below the function <tt>random</tt> gives
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a random number smaller than the indicated value. As you might have noticed there
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is a checkbox labeled <b>Relative</b>. If you check this, the new motion is added
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to the previous one. For example, if the instance is moving upwards and you
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add some motion to the left, the new motion will be upwards to the left.
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<p>
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<b><img src="images/action_movepoint.bmp"> Move Towards</b><br>
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This action gives a third way to specify a motion. You indicate a position and
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a speed and the instance starts moving with the speed towards the position.
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(It won't stop at the position!) For example, if you want a bullet to fly
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towards the position of the spaceship you can use as position <tt>spaceship.x, spaceship.y</tt>.
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(You will learn more about the use of variables like these below.)
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If you check the <b>Relative</b> box, you specify the position relative
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to the current position of the instance. (The speed is not taken relatively!)
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<p>
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<b><img src="images/action_hspeed.bmp"> Speed Horizontal</b><br>
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The speed of an instance consists of a horizontal part and a vertical part.
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With this action you can change the horizontal speed. A positive horizontal
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speed means a motion to the right. A negative one means a motion to the left.
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The vertical speed will remain the same. Use relative to increase the horizontal speed
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(or decrease it by providing a negative number).
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<p>
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<b><img src="images/action_vspeed.bmp"> Speed Vertical</b><br>
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In a similar way, with this action you can change the vertical speed of the instance.
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<p>
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<b><img src="images/action_gravity.bmp"> Set Gravity</b><br>
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With this action you can create gravity for this particular object.
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You specify a direction (angle between 0 and 360 degrees) and a speed,
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and in each step this amount of speed in the given direction is added
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to the current motion of the object instance. Normally you need a very
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small speed increment (like 0.01). Typically you want a downward direction
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(270 degrees). If you check the <b>Relative</b> box you increase the
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gravity speed and direction. Note that, contrary to real life,
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different object can have different gravity directions.
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<p>
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<b><img src="images/action_hreverse.bmp"> Reverse Horizontal</b><br>
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With this action you reverse the horizontal motion of the instance.
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This can for example be used when the object collides with a vertical wall.
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<p>
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<b><img src="images/action_vreverse.bmp"> Reverse Vertical</b><br>
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With this action you reverse the vertical motion of the instance.
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This can for example be used when the object collides with a horizontal wall.
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<p>
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<b><img src="images/action_friction.bmp"> Set Friction</b><br>
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Friction slows down the instances when they move. You specify the amount
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of friction. In each step this amount is subtracted from the speed
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until the speed becomes 0. Normally you want a very small number here (like 0.01).
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<p>
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<b><img src="images/action_jumpposition.bmp"> Jump to Position</b><br>
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Using this action you can place the instance in a particular position.
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You simply specify the x- and y-coordinate, and the instance is placed
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with its reference point on that position. If you check the <b>Relative</b> box,
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the position is relative to the current position of the instance.
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This action is often used to continuously move an instance.
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In each step we increment the position a bit.
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<p>
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<b><img src="images/action_jumpstart.bmp"> Jump to Start</b><br>
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This action places the instance back at the position where it was created.
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<p>
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<b><img src="images/action_jumprandom.bmp"> Jump to Random</b><br>
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This action moves the instance to a random position in the room.
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Only positions are chosen where the instance does not intersect any
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solid instance. You can specify the snapping used. If you specify
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positive values, the coordinates chosen with be integer multiples of
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the indicated values. This could for example be used to keep the instance
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aligned with the cells in your game (if any). You can specify a separate
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horizontal snapping and vertical snapping.
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<p>
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<b><img src="images/action_grid.bmp"> Align to Grid</b><br>
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With this action you can round the position of the instance to a grid.
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You can indicate both the horizontal and vertical snapping value (that is,
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the size of the cells of the grid). This can be very useful to make sure
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that instances stay on a grid.
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<p>
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<b><img src="images/action_wrap.bmp"> Wrap Screen</b><br>
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With this action you can let an instance wrap around, that is, when
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it leaves on one side of the room it reappears at the other side. This
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action is normally used in the <b>Outside</b> event. Note that the
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instance must have a speed for wrapping to work, cause the direction
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of wrapping is based on the direction of the motion. You can indicate
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whether to wrap only horizontal, only vertical, or in both directions.
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<p>
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<b><img src="images/action_contact.bmp"> Move to Contact</b><br>
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With this action you can move the instance in a given direction until a
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contact position with an object is reached. If there already is a collision
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at the current position the instance is not moved. Otherwise, the instance
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is placed just before a collision occurs. You can specify the direction but
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also a maximal distance to move. For example, when the instance is falling
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you can move a maximal distance down until an object is encountered. You can
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also indicate whether to consider solid object only or all objects. You typically
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put this action in the collision event to make sure that the instance stops
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in contact with the other instance involved in the collision.
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<p>
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<b><img src="images/action_bounce.bmp"> Bounce</b><br>
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When you put this action in the collision event with some object, the instance
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bounces back from this object in a natural way. If you set the parameter precise
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to false, only horizontal and vertical walls are treated correctly. When you set
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precise to true also slanted (and even curved) walls are treated correctly.
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This is though slower. Also you can indicate whether to bounce only against solid
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objects or against all objects. Please realize that the bounce is not completely
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accurate because this depends on many properties. But in many situations the
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effect is good enough.
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<!--END-->
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</body>
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</html>
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<!-- KEYWORDS
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moving actions
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bouncing
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gravity
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friction
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wrap
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align to grid
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--> |