13. Beginning with Graphics <<< Contents >>> 15. Fill Your Own Colors

14. Mishmash Drawing

If you don't like the word "mishmash" in the chapter title, you can replace it with anything else, but it is probably the best designation for what we are going to do.

First, we will try the basic graphical commands for drawing. Create a new program called Graphic or open the sample program.

We won't need Peter in our program, and so we will turn his visibility off by the visible command with the no parameter in the beginning of our program. The program will be based on a conditional repeating of commands cycle that can be ended by pressing the Esc key. Put this command behind the one that turns Peter's visibility off, and add a wait command into it.

Another very important task is making the squares in the item layer transparent. Edit the empty square item. In the color picker, choose the top left color (purple). It is a transparent color, which will enable us to see through the square with an item. Choose filled box as the drawing tool, and redraw the whole item with the transparent color.

If you will run the program now, you won't see anything but a black sheet. You see the graphic layer, which will be the basis for our next programs. Later, we will use both items and graphics together. After you try the first graphical command, you can draw something into the empty square item. You will see the graphic and a net of empty square pictures over it.

In the Basic Elements group, find the graphic group, drawing subgroup. It contains commands for drawing graphical elements. Drag the point command into the main program loop. It contains another four elements that specify the parameters of the point rendered.

The first parameter, pen color , specifies the color of the point. Color is a number, which can be kept in a numeric variable. We are not interested in its value so far, as we can use special functions to specify color. In a new command, the pen color element contains a color element. This is a color constant, which passes the selected color to the command. You can select a new color by double-clicking the color constant element. The color selection window appears. The selected color is indicated by the elevation of its field. Clicking selects a different color. The color will also appear in the color constant element.

In our program, we will render points with a random color. For this reason, we will discard the color constant element, and use the compound color components to color element (from the graphic group) instead of it. This component contains another three elements, red component (0 to 1) , green component (0 to 1) and blue component (0 to 1) . The components specify the level of individual colors in the resulting color. The closer is the value to 1, the brighter the component is. For example, yellow has the values of 1/1/0. A random color can be created by inserting random number (0 <= x < 1) components into the color components (the range for a random number is 0 to 1 as well).

Another parameter for the point command is the pen width element. It is a numeric value, which specifies how many graphical points wide will the point be. The point size will be generated randomly, and so we will insert a random number with the parameter of 9 here, which will create random points with the size of 1 to 9 graphical points (we don't have to care about zero, the point command modifies it to 1).

The last two elements of the command, horizontal X coordinate of point and vertical Y coordinate of point , specify the position, where the point will appear. The previous picture shows how graphical coordinates are numbered. It is the same as the numbering of squares, as we know it from previous chapters. The basic unit of Peter's coordinates is a unitary step. The length of the step is the same as a square width. The beginning of the coordinates is in the bottom left corner. As the coordinates are expressed by decimal numbers, we can specify the coordinates for squares, graphics and sprites in the same way, without any conversions.

The coordinates for the point will be specified randomly, as we know it from previous chapters, by using random numbers with the parameters of the width and height of the sheet. The resulting command for the random point will look like this:

Run the program. Color points of different sizes start appearing on the sheet. The rendering is not very quick. After each point in the loop, the program waits a little moment (55 ms), which means that the speed of rendering is 18 points per second.

This is a good time for discussing the program timing. As we already said, the wait command has, besides the waiting function, also a function for cooperation with other programs (and with the core of Windows). An advanced user can use the System Monitor program to verify that the Graphic program is a minimum load for the computer, and that the program speed is independent of the computer speed. To be accurate — the wait command does not represent an actual pause of a given length; it represents synchronization with the inner clock of the computer. For this reason, the program speed does not depend on the speed at which the commands between two wait commands are executed.

Try to fill a value of 0 into the wait command. The program will now produce very many points. It does not wait for the interval now; it runs at maximum speed. Yet, it ensures that the window sheet is rendered on the display at each pass through the loop. This is another function of the wait command — it ensures rendering. The program does not know when all graphical operations are finished, and so when it is a good time to render the window on the display. If the program rendered the window itself, the background of a game could appear, but not the characters in it. As a result, the background would show through the characters. For this reason, rendering is performed during the waiting, when all graphical operations are probably finished.

A tip for program optimization: The program redraws a rectangular part of the window, where changes were made. If you want to increase the program speed, render only the changed area of the graphic. On the other hand, this could lead to rendering many small parts of the graphic, which could be more demanding than rendering the whole window at a time.

Timing with the value of 0 is useful in situations, when you need higher program performance, or when the timing after 0.055 seconds is too rough. It ensures fluent redrawing of the window, maximum program speed, and sufficient cooperation with Windows. The program speed is dependent on the computer speed now. We could use System Monitor to see that the program consumes most of the computer performance, even if it seems to be in a relatively quiet state.

You can also try to disable timing completely by using the Turn Off button. If you run the program now, you see a noise of colors instead of points. Now, the program really runs at maximum speed, without any pauses. You may notice that the color noise is not fluent; the image is a bit choppy. It is so because the program ensures at least a minimum redrawing of the window to the display. If there is no wait command for about 0.2 seconds, the program redraws the window itself.

Let us get back to graphical commands. Add other graphical commands to the main program loop — line , box , filled box , circle , filled circle , sphere , triangle — and try to render them randomly. Use a random radius of 2 with circle, filled circle and sphere. Skip Filling , as it would not have much effect here.

The text display command is also interesting. It has more parameters than you may be used to, but don't worry. You don't have to set the parameters that don't interest you. Their default values will be used then. It is probably clear what the text to be displayed , pen color , horizontal X coordinate of text and vertical Y coordinate of text parameters mean.

A new element is the angle orientation of text . It is the angle, at which the text is turned around the bottom left corner. It is specified in radians, just like other angles in Peter. We can use the direction constants that we know from setting the directions of Peter and Lucy. If not specified, a direction of 0 is used (horizontally from left to right).

The height of characters element specifies the height of the characters in the text. It is specified in unitary steps. If not specified, the height of 0.5 will be used (half of the square height).

The relative width of characters (1 = usual) element represents a relative number indicating the width of the characters when compared to the normal width. A value of 1 is the normal width. Numbers higher than 1 specify wider characters, smaller numbers specify narrower characters. A special value is the number 0. This sets the recommended width for the type of characters used. It is similar to the normal width, but may differ slightly. If not specified, the default value of 0 is used (the recommended width).

The bold , italic , underline and strike out elements are logical switches that turn on special effects for the text. By default, all of these are turned off. The serifs switch turns on serif characters. By default, it is also turned off. The typewriter switch turns on characters with the same spacing and width. When it is turned off, characters have different widths (I is narrower than M). Unless specified otherwise, this switch is off as well.

The whole command for a random text is on the previous picture. It is quite long, and so the picture is separated into two parts. Test the program after you create the command.

One of the most powerful aspects of graphics are pictures. You can use pictures for anything that is not predefined in Peter. You can create moving characters, a window with animated buttons, a moving background for a game, or snapshots.

The commands and functions for pictures are in the graphic group, pictures subgroup. The basic command is draw picture . Besides obvious parameters, such as the picture to be rendered and its coordinates, the command also has more parameters that make it possible to draw only a specific part of the picture.

In our test program, we will try to render a picture randomly. Before you start drawing, you can look at the Library of Variables and Functions. With Peter, you also get many pictures. Open the [examples]\Drawing group. You will surely find a picture that you will like. When browsing, click to select the first picture in the group, and then scroll the selection cursor up and down by using the arrow keys. The editing window will show previews of the pictures.

Drag the selected picture into the Global Variables and Functions window. If the picture has a one-color background, you can fill the background with the transparent color (by using the Filler function) to display the picture without any background.

The command for random drawing of the picture is shown above. If you want to draw a picture with a random size, you can use the change picture size function. The new picture width will be random, and will be based on the original size shrunk to approximately one half. It is not necessary to specify a new height; it will be adjusted to the new width automatically.

Note: It is better to use a larger picture and a higher level of reduction. This ensures a higher quality of the resulting picture than using a smaller picture.

13. Beginning with Graphics <<< Contents >>> 15. Fill Your Own Colors