mode7.h File Reference

SNES Mode 7 Support. More...

#include <snes/types.h>

Go to the source code of this file.

Macros
#define	MODE7_FLIP_H   0x01
	Flip Mode 7 plane horizontally.
#define	MODE7_FLIP_V   0x02
	Flip Mode 7 plane vertically.
#define	MODE7_TILE0   0xC0
	Show tile 0 when out of bounds.
#define	MODE7_TRANSPARENT   0x80
	Show transparent when out of bounds.
#define	MODE7_WRAP   0x00
	Wrap around when out of bounds (default)

Functions
void	mode7Init (void)
	Initialize Mode 7.
void	mode7Rotate (u16 degrees)
	Set rotation in degrees (0-359)
void	mode7SetAngle (u8 angle)
	Set Mode 7 rotation angle.
void	mode7SetCenter (s16 x, s16 y)
	Set Mode 7 center point.
void	mode7SetMatrix (s16 a, s16 b, s16 c, s16 d)
	Set Mode 7 matrix directly.
void	mode7SetPivot (u8 x, u8 y)
	Set pivot point (screen coordinates)
void	mode7SetScale (u16 scale_x, u16 scale_y)
	Set Mode 7 scale factors.
void	mode7SetScroll (s16 x, s16 y)
	Set Mode 7 scroll position.
void	mode7SetSettings (u8 settings)
	Set Mode 7 settings register.
void	mode7Transform (u16 degrees, u16 scalePercent)
	Set rotation and scale together.

Detailed Description

SNES Mode 7 Support.

Functions for Mode 7 rotation and scaling effects. Mode 7 is the SNES's hardware rotation/scaling mode, famously used in F-Zero, Super Mario Kart, and Pilotwings.

Usage

#include <snes.h>
 
// Initialize Mode 7
mode7Init();
 
// Set scale (0x0100 = 1.0, 0x0080 = 0.5, 0x0200 = 2.0)
mode7SetScale(0x0100, 0x0100);
 
// Set rotation angle (0-255, where 256 = 360 degrees)
mode7SetAngle(angle);
 
// In main loop
while (1) {
    WaitForVBlank();
    angle++;
    mode7SetAngle(angle);
}

Mode 7 VRAM Layout

Mode 7 uses a special interleaved VRAM format:

• Tilemap in low bytes of VRAM words 0x0000-0x3FFF
• Tile data in high bytes of VRAM words 0x0000-0x3FFF

Use mode7LoadGraphics() or set up DMA manually with interleaved data.

Author

OpenSNES Team

Copyright

MIT License

Macro Definition Documentation

MODE7_FLIP_H

#define MODE7_FLIP_H   0x01

Flip Mode 7 plane horizontally.

MODE7_FLIP_V

#define MODE7_FLIP_V   0x02

Flip Mode 7 plane vertically.

MODE7_TILE0

#define MODE7_TILE0   0xC0

Show tile 0 when out of bounds.

MODE7_TRANSPARENT

#define MODE7_TRANSPARENT   0x80

Show transparent when out of bounds.

MODE7_WRAP

#define MODE7_WRAP   0x00

Wrap around when out of bounds (default)

Function Documentation

mode7Init()

void mode7Init

(

void

)

Initialize Mode 7.

Sets up default scale (1.0), identity matrix, center point (128,128), and scroll position. Call this before using other Mode 7 functions.

Note

This does NOT set BGMODE to Mode 7. You must do that separately:

REG_BGMODE = BGMODE_MODE7;
REG_M7SEL = 0x00;  // No flip, wrap around
REG_TM = TM_BG1;   // Enable BG1

mode7Rotate()

void mode7Rotate

(

u16

degrees

)

Set rotation in degrees (0-359)

Convenience function that converts degrees to the internal 0-255 format.

Parameters

degrees

Rotation angle in degrees (0-359)

mode7Rotate(45);   // Rotate 45 degrees
mode7Rotate(180);  // Rotate 180 degrees

mode7SetAngle()

void mode7SetAngle

(

u8

angle

)

Set Mode 7 rotation angle.

Sets the rotation angle and recalculates the transformation matrix. The angle is 0-255 where 256 would equal 360 degrees (wraps at 256).

Parameters

angle

Rotation angle (0-255)

This function:

1. Looks up sin/cos from table
2. Multiplies by current scale using hardware multiplier
3. Writes the 4 matrix values (M7A, M7B, M7C, M7D) to PPU

mode7SetCenter()

void mode7SetCenter	(	s16	x,
		s16	y
	)

Set Mode 7 center point.

Sets the center of rotation/scaling. Default is (128, 128).

Parameters

x	Center X coordinate (13-bit signed, -4096 to 4095)
y	Center Y coordinate (13-bit signed, -4096 to 4095)

mode7SetMatrix()

void mode7SetMatrix	(	s16	a,
		s16	b,
		s16	c,
		s16	d
	)

Set Mode 7 matrix directly.

For advanced users who need direct control over the transformation matrix. Bypasses the angle/scale system.

The matrix maps screen (x,y) to Mode 7 plane (X,Y): X = A*(x-cx) + B*(y-cy) + sx + cx Y = C*(x-cx) + D*(y-cy) + sy + cy

Parameters

a	Matrix A (1.7.8 fixed point)
b	Matrix B (1.7.8 fixed point)
c	Matrix C (1.7.8 fixed point)
d	Matrix D (1.7.8 fixed point)

mode7SetPivot()

void mode7SetPivot	(	u8	x,
		u8	y
	)

Set pivot point (screen coordinates)

Sets the rotation center using screen coordinates (0-255). The pivot point is where the Mode 7 plane appears to rotate around.

Parameters

x	Screen X coordinate (0-255)
y	Screen Y coordinate (0-223)

mode7SetPivot(128, 112);  // Center of screen
mode7SetPivot(0, 0);      // Top-left corner

mode7SetScale()

void mode7SetScale	(	u16	scale_x,
		u16	scale_y
	)

Set Mode 7 scale factors.

Sets the X and Y scale for Mode 7 transformation. Scale is in 8.8 fixed point format:

• 0x0100 = 1.0 (normal size)
• 0x0080 = 0.5 (zoomed in / larger)
• 0x0200 = 2.0 (zoomed out / smaller)

Parameters

scale_x	Horizontal scale (8.8 fixed point)
scale_y	Vertical scale (8.8 fixed point)

Note

Call mode7SetAngle() after changing scale to update the matrix.

mode7SetScroll()

void mode7SetScroll	(	s16	x,
		s16	y
	)

Set Mode 7 scroll position.

Sets the scroll offset for the Mode 7 plane.

Parameters

x	Horizontal scroll (13-bit signed)
y	Vertical scroll (13-bit signed)

mode7SetSettings()

void mode7SetSettings

(

u8

settings

)

Set Mode 7 settings register.

Controls flipping and out-of-bounds behavior.

Parameters

settings

M7SEL value: Bit 1: Flip vertically Bit 0: Flip horizontally Bits 7-6: Out of bounds behavior (0=wrap, 0x80=transparent, 0xC0=tile 0)

mode7Transform()

void mode7Transform	(	u16	degrees,
		u16	scalePercent
	)

Set rotation and scale together.

Combined transformation with rotation in degrees and percentage-based scaling.

Parameters

degrees	Rotation angle in degrees (0-359)
scalePercent	Scale as percentage (100 = normal, 50 = half, 200 = double)

mode7Transform(45, 100);   // 45 degree rotation, normal scale
mode7Transform(0, 50);     // No rotation, 2x zoom in
mode7Transform(90, 200);   // 90 degrees, 0.5x zoom out