SCRN ("NRCS") - Screen

Author(s): Gonhex
Research: NOCASH

The screen section, also known as tile map, is used to create an image by rearranging and flipping tiles. Each position on the raster gets one. This can save a lot of memory since duplicated tiles can be avoided.

Table of Contents

• Data Structure
  • Section Container
  • SCRN Container
  • Tile Properties
• Specification
  • Files

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Data Structure

Section Container

struct ContainerSectionSCRN
{
    /* 0x0 */ struct NitroSectionHeader sectionHeader;
    /* 0x8 */ struct ContainerSCRN sectionData;
}; // entry size = sectionHeader.lengthSection

Field Name	Description	Data Type
sectionHeader	Header of this section. sectionHeader.signature = "NRCS".	NitroSectionHeader
sectionData	Content of this section.	ContainerSCRN

SCRN Container

struct ContainerSCRN
{
    // header
    /* 0x0 */ uint16_t widthInPixel;
    /* 0x2 */ uint16_t heightInPixel;
    /* 0x4 */ uint16_t unknown0;
    /* 0x6 */ uint16_t unknown1;
    /* 0x8 */ uint32_t lengthDataScreen;
    
    // data
    /* 0xC */ struct TileProperties dataScreen[widthInPixel >> 3][heightInPixel >> 3];
}; // entry size = 0xC + lengthDataScreen

Field Name	Description	Data Type
widthInPixel	Width of the image in pixel.	uint16_t
heightInPixel	Height of the image in pixel.	uint16_t
unknown0	Unused mode?	uint16_t
unknown1	Unused mode?	uint16_t
lengthDataScreen	Length of the screen data section in bytes.	uint32_t
dataScreen	Two-dimensional tile map to create an image by indexing and flipping tiles.	TileProperties[][]

Tile Properties

struct TileProperties
{
    /* 0x0 */ uint16_t tileIndex : 10;     // 0b00000011'11111111
              uint16_t horizontalFlip : 1; // 0b00000100'00000000
              uint16_t verticalFlip : 1;   // 0b00001000'00000000
              uint16_t paletteIndex : 4;   // 0b11110000'00000000
}; // entry size = 0x2

Field Name	Description	Data Type
tileIndex	Index of the tile (8x8 pixel image) within the character graphic.	uint16_t
horizontalFlip	Flip/mirror tile horizontally.	uint16_t
verticalFlip	Flip/mirror tile vertically.	uint16_t
paletteIndex	Index of the palette used for this tile.	uint16_t

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Specification

Files

• Nitro Screen Runtime