Difference between revisions of "Sprites"
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Originally sprites referred to independent objects that are composited together, by hardware, with other elements such as a background or tiles. The composition occurs as each scan line is prepared for the video output device, without involvement of the main CPU and without the need for a full-screen frame buffer. Sprites can be positioned or altered by setting attributes used during the hardware composition process. | Originally sprites referred to independent objects that are composited together, by hardware, with other elements such as a background or tiles. The composition occurs as each scan line is prepared for the video output device, without involvement of the main CPU and without the need for a full-screen frame buffer. Sprites can be positioned or altered by setting attributes used during the hardware composition process. | ||
| − | Vicky is able to render | + | Vicky is able to render 64 non-multiplexed sprites with a resolution of 32x32 pixels each. Just as bitmaps, a [[LUT]] is required for selecting 256 out of 16.777.216 colors. |
== Sprite Registers == | == Sprite Registers == | ||
| − | Each Sprite has registers composed of a total of 8 bytes for manipulation, starting at $AF: | + | Each Sprite has registers composed of a total of 8 bytes for manipulation, starting at $AF:0C00 and spanning through to $AF:0DFF. |
| + | |||
| + | The first set of sprite manipulation registers are shown below: | ||
{| {{Wikitable}} | {| {{Wikitable}} | ||
!Attribute | !Attribute | ||
| − | ! | + | !Address |
| + | |- | ||
| + | |SP00_CONTROL_REG||= $AF:0C00 | ||
|- | |- | ||
| − | | | + | |SP00_ADDY_PTR_L||= $AF:0C01 |
|- | |- | ||
| − | | | + | |SP00_ADDY_PTR_M||= $AF:0C02 |
|- | |- | ||
| − | | | + | |SP00_ADDY_PTR_H||= $AF:0C03 |
|- | |- | ||
| − | | | + | |SP00_X_POS_L||= $AF:0C04 |
|- | |- | ||
| − | | | + | |SP00_X_POS_H||= $AF:0C05 |
|- | |- | ||
| − | | | + | |SP00_Y_POS_L||= $AF:0C06 |
|- | |- | ||
| − | | | + | |SP00_Y_POS_H||= $AF:0C07 |
|} | |} | ||
| + | For each successive sprite, add +8 to the address registers. | ||
| − | The | + | The sprite control register (SPxy_CONTROL_REG) is always the first byte of the 8 byte block. The register is configured as follows: |
{| {{Wikitable}} | {| {{Wikitable}} | ||
!Attribute | !Attribute | ||
| − | ! | + | !Bit |
|- | |- | ||
| − | | | + | |SPRITE_Enable||= $01 |
|- | |- | ||
| − | | | + | |SPRITE_LUT0||= $02 |
|- | |- | ||
| − | | | + | |SPRITE_LUT1||= $04 |
|- | |- | ||
| − | | | + | |SPRITE_LUT2||= $08 |
|- | |- | ||
| − | | | + | |SPRITE_DEPTH0||= $10 |
|- | |- | ||
| − | | | + | |SPRITE_DEPTH1||= $20 |
|- | |- | ||
| − | | | + | |SPRITE_DEPTH2||= $40 |
|- | |- | ||
| − | | | + | |SPRITE_Collision_On||= $80 |
|} | |} | ||
Revision as of 18:37, 27 June 2021
Sprite is a computer graphics term for a two-dimensional bitmap that is integrated into a larger scene.
Originally sprites referred to independent objects that are composited together, by hardware, with other elements such as a background or tiles. The composition occurs as each scan line is prepared for the video output device, without involvement of the main CPU and without the need for a full-screen frame buffer. Sprites can be positioned or altered by setting attributes used during the hardware composition process.
Vicky is able to render 64 non-multiplexed sprites with a resolution of 32x32 pixels each. Just as bitmaps, a LUT is required for selecting 256 out of 16.777.216 colors.
Sprite Registers
Each Sprite has registers composed of a total of 8 bytes for manipulation, starting at $AF:0C00 and spanning through to $AF:0DFF.
The first set of sprite manipulation registers are shown below:
| Attribute | Address |
|---|---|
| SP00_CONTROL_REG | = $AF:0C00 |
| SP00_ADDY_PTR_L | = $AF:0C01 |
| SP00_ADDY_PTR_M | = $AF:0C02 |
| SP00_ADDY_PTR_H | = $AF:0C03 |
| SP00_X_POS_L | = $AF:0C04 |
| SP00_X_POS_H | = $AF:0C05 |
| SP00_Y_POS_L | = $AF:0C06 |
| SP00_Y_POS_H | = $AF:0C07 |
For each successive sprite, add +8 to the address registers.
The sprite control register (SPxy_CONTROL_REG) is always the first byte of the 8 byte block. The register is configured as follows:
| Attribute | Bit |
|---|---|
| SPRITE_Enable | = $01 |
| SPRITE_LUT0 | = $02 |
| SPRITE_LUT1 | = $04 |
| SPRITE_LUT2 | = $08 |
| SPRITE_DEPTH0 | = $10 |
| SPRITE_DEPTH1 | = $20 |
| SPRITE_DEPTH2 | = $40 |
| SPRITE_Collision_On | = $80 |
