main.c File Reference

SuperFX 3D — auto-rotating wireframe cube (2-axis rotation). More...

#include <snes.h>
#include <snes/superfx.h>

Functions
void	buildEdges (void)
	Build edge buffer from projected vertices.
void	gsuSetProgram (void)
int	main (void)
void	rotateVertex (u16 idx)
	Rotate one vertex, store projected screen coords (clamped).
void	writeEdgesToSRAM (void)

Variables
static const u8	ce []
static const u16	cube_pal []
static const s16	cvx [] = {-25, 25, 25,-25,-25, 25, 25,-25}
static const s16	cvy [] = {-25,-25, 25, 25,-25,-25, 25, 25}
static const s16	cvz [] = {-25,-25,-25,-25, 25, 25, 25, 25}
u8	edge_buffer [48]
s16	g_cax
s16	g_cay
u8	g_px [8]
u8	g_py [8]
s16	g_sax
s16	g_say
static const s8	sin_tab [256]

Detailed Description

SuperFX 3D — auto-rotating wireframe cube (2-axis rotation).

Demonstrates GSU (SuperFX) coprocessor execution. The 65816 sets up a Mode 1 bitmap framebuffer in VRAM, then hands control to a small GSU program (compiled separately by wla-superfx) that rotates a cube's 8 vertices via the GSU's hardware sine LUT and writes the edge bytes into SRAM. The 65816 streams those edge bytes back to VRAM each frame via DMA. The result: a smoothly rotating 3D wireframe entirely driven by the GSU.

SNES Concepts

• GSU launch via gsuLaunch() (gsuRun + cache prefetch)
• GSU ↔ 65816 communication via SRAM as shared scratch
• DMA full-frame transfer from SRAM to VRAM each frame
• HDMA-driven force-blank during transfer (gsuSetupHdmaBlanking)

What to Observe

• A wireframe cube rotates continuously on two axes (X and Y).
• No input — the rotation is autonomous; reset to restart from the initial angle.
• GSU presence is detected via the ROM header bits; Mesen2 is the canonical emulator for this example (snes9x's GSU detection is unreliable on our header layout — see KNOWN_LIMITATIONS).

Modules Used

console, sprite, dma, background, input, superfx

See also

superfx.h, dma.h, background.h

Function Documentation

buildEdges()

void buildEdges

(

void

)

Build edge buffer from projected vertices.

gsuSetProgram()

void gsuSetProgram ( void )

extern

main()

int main

(

void

)

rotateVertex()

void rotateVertex

(

u16

idx

)

Rotate one vertex, store projected screen coords (clamped).

writeEdgesToSRAM()

void writeEdgesToSRAM ( void )

extern

Variable Documentation

ce

const u8 ce[]

static

Initial value:

                   = {
    0,1, 1,2, 2,3, 3,0, 4,5, 5,6, 6,7, 7,4, 0,4, 1,5, 2,6, 3,7,
}

cube_pal

const u16 cube_pal[]

static

Initial value:

                          = {
    RGB(0,0,4), RGB(0,0,10), RGB(0,0,16), RGB(0,0,24),
    RGB(0,10,31), RGB(0,20,31), RGB(0,31,31), RGB(0,31,16),
    RGB(16,31,0), RGB(31,31,0), RGB(31,16,0), RGB(31,0,0),
    RGB(31,0,16), RGB(31,0,31), RGB(20,20,20), RGB(31,31,31),
}

cvx

const s16 cvx[] = {-25, 25, 25,-25,-25, 25, 25,-25}

static

cvy

const s16 cvy[] = {-25,-25, 25, 25,-25,-25, 25, 25}

static

cvz

const s16 cvz[] = {-25,-25,-25,-25, 25, 25, 25, 25}

static

edge_buffer

u8 edge_buffer[48]

extern

g_cax

s16 g_cax

g_cay

s16 g_cay

g_px

u8 g_px[8]

g_py

u8 g_py[8]

g_sax

s16 g_sax

g_say

s16 g_say

sin_tab

const s8 sin_tab[256]

static

Initial value:

                        = {
      0,   3,   6,   9,  12,  16,  19,  22,  25,  28,  31,  34,  37,  40,  43,  46,
     49,  51,  54,  57,  60,  63,  65,  68,  71,  73,  76,  78,  81,  83,  85,  88,
     90,  92,  94,  96,  98, 100, 102, 104, 106, 107, 109, 111, 112, 113, 115, 116,
    117, 118, 120, 121, 122, 122, 123, 124, 125, 125, 126, 126, 126, 127, 127, 127,
    127, 127, 127, 127, 126, 126, 126, 125, 125, 124, 123, 122, 122, 121, 120, 118,
    117, 116, 115, 113, 112, 111, 109, 107, 106, 104, 102, 100,  98,  96,  94,  92,
     90,  88,  85,  83,  81,  78,  76,  73,  71,  68,  65,  63,  60,  57,  54,  51,
     49,  46,  43,  40,  37,  34,  31,  28,  25,  22,  19,  16,  12,   9,   6,   3,
      0,  -3,  -6,  -9, -12, -16, -19, -22, -25, -28, -31, -34, -37, -40, -43, -46,
    -49, -51, -54, -57, -60, -63, -65, -68, -71, -73, -76, -78, -81, -83, -85, -88,
    -90, -92, -94, -96, -98,-100,-102,-104,-106,-107,-109,-111,-112,-113,-115,-116,
   -117,-118,-120,-121,-122,-122,-123,-124,-125,-125,-126,-126,-126,-127,-127,-127,
   -127,-127,-127,-127,-126,-126,-126,-125,-125,-124,-123,-122,-122,-121,-120,-118,
   -117,-116,-115,-113,-112,-111,-109,-107,-106,-104,-102,-100, -98, -96, -94, -92,
    -90, -88, -85, -83, -81, -78, -76, -73, -71, -68, -65, -63, -60, -57, -54, -51,
    -49, -46, -43, -40, -37, -34, -31, -28, -25, -22, -19, -16, -12,  -9,  -6,  -3,
}