**Introduction**

AlDraw is a tool for making pictures using geometric construction. Geometric construction only allows you to draw straight lines and circles. AlDraw has the further restriction that you can only draw using the green points. New points are generated by intersecting lines.

These help pages describes how the controls work. If you want to know more about how to do geometrical construction, you can check out the wiki.

**Basic Buttons:**

Clear: This button will clear any changes you've made and revert to the default circle with seven points. You can also clear by pressing Ctrl-Space.

Undo: This will undo your previous drawing action. You can click it multiple times to undo multiple actions. You can also undo by pressing Ctrl-Z.

Redo: This will redo an action that you undid with the undo button. It can be used multiple times, but will not do anything if you make another drawing action. You can also redo by pressing Ctrl-Y or Ctrl-Shift-Z.

Zoom to Fit: This will adjust the size and position of the drawing so it will fit in the window. You can also zoom to fit by pressing Ctrl-A.

Save/Load: You can save your drawing or load previously saved drawings here.

Download: Download your drawing to your computer either as a PNG or SVG file.

**Draw Group:**

Draw Segment: Click two points. The points will be the endpoints of the new segment.

Draw Ray: Click two points. The first point will be the endpoint of the new ray, and it will go through the second.

Draw Line: Click two points. The new line will go through the two points.

Draw Arc: Click three points. The first point will be the center of the new arc. The second point will be the arc's radius and start angle. The third point will be the arc's end angle. Keep in mind arcs are always drawn clockwise from the second point to the third point.

Draw Circle: Click two points. The first point will be the center of the new circle. The second point will be the radius.

**Erase Group:**

Erase Segment: Click two points. The points will be the endpoints of the segment to be erased.

Erase Ray: Click two points. The first point will be the endpoint of the ray to be erased, and it will go through the second.

Erase Line: Click two points. The line to be erased will go through the two points.

Erase Arc: Click three points. The first point will be the center of the arc to be erased. The second point will be the arc's radius and start angle. The third point will be the arc's end angle. Keep in mind arcs are always drawn clockwise from the second point to the third point.

Erase Circle: Click two points. The first point will be the center of the circle to be erased. The second point will be the radius.

Erase Point: Click one point. It will be erased.

**Shortcuts Group: **

Find Midpoint: Click two points. This will create a point halfway between the two points.

Trisect Segment: Click two points. This will create two points equally spaced between the two you clicked.

Perpendicular Bisector: Click two points. This will create a line passing through the midpoint of the two points, which is perpendicular to the and the line defined by those two points. A line does not need to be drawn between the two points in order to use the perpendicular bisector tool.

Angle Bisector: Click three points. This will create the line that bisects the angle defined by those three points. The line will pass through the second point clicked.

Tangent Line: Click two points. This will create the line perpendicular to the line defined by the two points that passes through the second point. It's named this because the line created is tangent to a circle that is centered on the first point, and passes through the second point, but you don't need a circle to use the tool.

Parallel Line: Click three points. This will create the line parallel to the line defined by the first two points that passes through the third point.

Circumscribe Triangle: Click three points. This will create the circle that passes through those three points.

Non-collapsing Compass: Click three points. This will create the circle with a radius equal to the distance between the first two points, centered on the third point.

**Color Group:**

Fill Color: Click an enclosed area. This will fill the area with the selected color.

Erase Color: Click a colored area. This will erase the color you clicked.

Pick Color: Click a colored area. This will select the color of the area.

Select Color: Choose the color that will be used for "Fill Color".

**View Group:**

Pan: Click and drag the screen. It will move to follow the cursor.

Rotate: Click and drag the screen. It will rotate to follow the cursor.

Angle: This shows the angle, in degrees, that the drawing is currently at. Changing it will rotate the drawing to that angle. The default angle is 0.

Zoom In: This makes the drawing larger. You can also zoom in with the scroll wheel.

Zoom Out: This makes the drawing smaller. You can also zoom out with the scroll wheel.

Show Lines: This toggles whether the lines are visible or not. Even when not visible, the lines are still there, and can still be used to generate points and color areas.

Show Points: This toggles whether the points are visible or not. Even when not visible, the points are still there, and can still be used to draw.