A small glossary for terms, phrases and abbreviations used in Oldskool Demomaker (OSDM) by Testaware
The RGB (Red/Green/Blue) Color Value of an Image or Effect that should not be rendered and thus appear to be transparent to let objects behind it to become visible.
Alpha Transparency is a value between 1-100 (and 0-255 in OSDM Script) that specifies how transparent an object is being rendered. A value of 100 (or 255) makes it entirely non-transparent/opaque, None (or 0) makes it practically invisible with 99 (253) levels in between.
Specifies the position of an object or the amount of movement on the horizontal layer or width. The value of X is 0 at the relative center position. The value of X is the expression of the distance to a point in space in relationship to the relative center. Positions left to the relative center are expressed by a negative value for X while positions to the right are expressed by a positive value.
Specifies the position of an object or the amount of movement on the vertical layer or height
Specifies the position of an object or amount of movement on the 3rd dimension that emulates space and depth or closeness.
The relative distance in space from a virtual center where the values for X,Y and Z are 0.
The location of the virtual center in space vary between the different effects and features of OSDM. For the LOGO as an example, the X,Y coordinate 0,0 is located at the top left corner of the intro screen, while for a sprite the 0,0 center is located in the center of the sprite itself.
To display a sprite of 100 pixels width and 100 pixels height in the upper left corner of the screen, the X/Y coordinate would be 50,50. To display the same sprite in the center of the intro screen, coordinates vary depending on the specified display resolution for the intro. If a resolution of 640×480 pixels is configured, the X/Y coordinates for the sprite to appear right in the middle of the intro would be 370, 290.
A copper effect is basically the cycling/shifting of color values. Older computers with limited graphical capacities were only capable of rendering graphics with a very limited amount of different colors. The VGA standard of old PC's for example was limited to 256 different colors that could be displayed on the screen at any given time. The color palette used was basically a list from 0 to 255. Individual color values were defined by levels between 0-255 of Red/Green/Blue (RGB). Color 0 could be defined as 255,0,0 for example, which represents the pure color Red. Color 1 could be defined as 255,255,0 for example, which represents the pure color Yellow. And this would go on until Color number 255. Every dot on the screen is defined by it's location on the screen by X and Y coordinates and the color number in the palette to be used to render the dot (or pixel). The copper effect basically copies the color values from color X to X+1 and X+1 to X+2 etc. 0→1, 1→2, …, 255→0 without changing the definition of the pixels on the screen itself. Only the color of each pixel changes as a result of the effect. This effect could be limited to only certain colors of the entire palette to only affect pixels of an image that were drawn using those particular colors, while the remaining pixels of the image where other colors were used would not be affected by the copper effect. Copper effects work well with gradients , like between white and black with several levels of gray in between them. The copper effect looks somewhat like a wave in those instances or can emulate movement where the is in fact isn't any movement at all.