Sprite Sheets
sprite sheets

Sprite Sheets

For Ecco The Dolphin and Ecco 2: The Tides Of Time

A sprite sheet is a way of organizing multiple animation sequences onto a single file. Each sequence can represent an action of a character or object. The animations are typically organized in a particular order over a sheet with a bright background. The background color acts as a chroma key that is later removed when a frame from an animation is required. The purpose of a sprite sheet is to store all the animations of an object onto a single sheet rather than multiple individual files. Sprite sheets make it easier for people to visualize all the animation sequences for an object.

In the video game Sonic Mania, all animations for a character might be separated by an action. What makes the sprite sheets from it unique are how the chromo key is used. Instead of using a special color for the background, the designers instead opted to put each animation frame in a box. This allows the game to only select what is contained in the box. The sheet has an overall color assigned to it that helps the game know where one frame ends and another frame begins.

sonic mania sprite sheet

Sonic Mania encapsulates a sprite's frame in a box with a chroma key. The sheets background color is used as a sorta chromo key to help separate the animations.

Ecco the Dolphin PC uses a different type of sprite sheet. Each character or object are stored in .zlm files (which contain the high definition sprites). The best way to visualize the contents of these files is like one giant column with each animation frame stacked on top of each other. A frame has bitmap data and a mask that is used to clean up the bitmap data once it decompresses. Unlike a sprite sheet, Ecco PC sprites maximize space by only using what they need.

The Mega Drive versions of Ecco the Dolphin use a different approach when it comes to sprites. They are broken up and stored as 8 by 8 pixel tiles. Sprites are reconstructed by data that instructs the game on which tiles to use and what order to place them in. Using tiles isn’t so much a choice by the designer but one by the hardware. A Mega Drive expects all graphics to be stored as tiles. The reason for this has to do with a piece of circuitry inside the Mega Drive called the VDP, or Video Digital Processor. The VDP uses tiles and color palettes to construct a screen. The programmers job is to tell the VDP which tile to use, where it should be positioned and which palette it should use. As you can see the Mega Drive is the most complex when it comes to storing sprites.

Our sprite sheets were designed to be simple. The backgrounds consist of a bright cyan that serves the purpose to make everything from an object’s frame visible. All objects are broken up into separate lines. Each line represents a single animation sequence. An animation sequence can be described as an action such as walking to the left, or throwing a baseball. Separating the animations by line helps those viewing the sheet know where an animation ends and a new one begins.

To create our sprite sheets we designed a special piece of software. This software can read the individual sprite files from a directory and render them on screen like text in a word processor. We used special filenames that helped the program group the animations onto separate lines. Once the sprite sheet is rendered it can be saved into a file. Adjustments to the program can be made to change the rendering process as we see fit.

Our goal was to create these sprite sheets for you! They are free to use for your own personal projects as long as you give credit to us by linking to our website: https://eccothedolphin.online