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package tests
import (
"testing"
"crecher.net/gones/v2/ppu"
)
// oam stores y - 1, so a sprite with y shows from scanline y + 1
func setSprite(p *ppu.PPU, index int, y, tile, attr, x uint8) {
p.WriteRegister(0x2003, uint8(index*4))
for _, b := range []uint8{y, tile, attr, x} {
p.WriteRegister(0x2004, b)
}
p.WriteRegister(0x2003, 0)
}
// tile 1 from newSceneWithTile1: row 0 is color 1, row 1 is color 2
// sprite palette 0: 1 = blue, 2 = red, 3 = white. palette 1: 1 = white
func newSpriteScene() *ppu.PPU {
p := newSceneWithTile1()
writeVRAM(p, 0x3F10, 0x0F, 0x21, 0x16, 0x30)
writeVRAM(p, 0x3F15, 0x30)
for i := 0; i < 64; i++ {
setSprite(p, i, 0xFF, 0, 0, 0)
}
return p
}
func checkPixels(t *testing.T, p *ppu.PPU, tests []struct {
x, y int
want uint32
}) {
t.Helper()
for _, tt := range tests {
if got := pixel(p, tt.x, tt.y); got != tt.want {
t.Errorf("pixel(%d,%d) = %#08x, want %#08x", tt.x, tt.y, got, tt.want)
}
}
}
type px = struct {
x, y int
want uint32
}
func TestSpriteDrawsOneLineBelowOAMY(t *testing.T) {
p := newSpriteScene()
setSprite(p, 0, 9, 1, 0, 16)
p.WriteRegister(0x2001, 0x10)
runFrames(p)
checkPixels(t, p, []px{
{16, 9, black},
{16, 10, blue},
{23, 10, blue},
{24, 10, black},
{15, 10, black},
{16, 11, red},
{16, 12, black},
})
}
func TestSpriteWithYZeroFirstShowsOnLineOne(t *testing.T) {
p := newSpriteScene()
setSprite(p, 0, 0, 1, 0, 16)
p.WriteRegister(0x2001, 0x10)
runFrames(p)
checkPixels(t, p, []px{{16, 0, black}, {16, 1, blue}})
}
func TestSpriteFlipHorizontal(t *testing.T) {
p := newSpriteScene()
writeVRAM(p, 0x0020, 0x80)
setSprite(p, 0, 9, 2, 0, 16)
setSprite(p, 1, 9, 2, 0x40, 64)
p.WriteRegister(0x2001, 0x10)
runFrames(p)
checkPixels(t, p, []px{
{16, 10, blue}, {23, 10, black},
{64, 10, black}, {71, 10, blue},
})
}
func TestSpriteFlipVertical(t *testing.T) {
p := newSpriteScene()
setSprite(p, 0, 9, 1, 0x80, 16)
p.WriteRegister(0x2001, 0x10)
runFrames(p)
checkPixels(t, p, []px{{16, 10, black}, {16, 16, red}, {16, 17, blue}})
}
func TestSpritePaletteSelect(t *testing.T) {
p := newSpriteScene()
setSprite(p, 0, 9, 1, 0x01, 16)
p.WriteRegister(0x2001, 0x10)
runFrames(p)
checkPixels(t, p, []px{{16, 10, white}})
}
func TestSpritePatternTableSelect(t *testing.T) {
p := newSpriteScene()
writeVRAM(p, 0x1018, 0xFF)
setSprite(p, 0, 9, 1, 0, 16)
p.WriteRegister(0x2000, 0x08)
p.WriteRegister(0x2001, 0x10)
runFrames(p)
checkPixels(t, p, []px{{16, 10, red}})
}
func TestSprite8x16(t *testing.T) {
p := newSpriteScene()
writeVRAM(p, 0x0020, 0xFF)
writeVRAM(p, 0x0030, 0xFF)
writeVRAM(p, 0x0038, 0xFF)
setSprite(p, 0, 9, 2, 0, 16)
p.WriteRegister(0x2000, 0x20)
p.WriteRegister(0x2001, 0x10)
runFrames(p)
// rows 0-7 come from tile 2, rows 8-15 from tile 3
checkPixels(t, p, []px{{16, 10, blue}, {16, 11, black}, {16, 18, white}, {16, 26, black}})
}
func TestSpritePriority(t *testing.T) {
// background tile 1 at x 16-23: line 1 is color 2 (red), line 2 is transparent
scene := func(attr uint8) *ppu.PPU {
p := newSpriteScene()
writeVRAM(p, 0x2002, 1)
setSprite(p, 0, 0, 1, attr, 16)
p.WriteRegister(0x2001, 0x1E)
runFrames(p)
return p
}
checkPixels(t, scene(0), []px{{16, 1, blue}, {16, 2, red}})
// behind the background it only shows through transparent pixels
checkPixels(t, scene(0x20), []px{{16, 1, red}, {16, 2, red}})
}
func TestSpriteLimitOf8PerLine(t *testing.T) {
p := newSpriteScene()
for i := 0; i < 9; i++ {
setSprite(p, i, 9, 1, 0, uint8(i*12))
}
p.WriteRegister(0x2001, 0x1E)
runFrames(p)
runToDot(p, 50, 0)
checkPixels(t, p, []px{{84, 10, blue}, {96, 10, black}})
if p.ReadRegister(0x2002)&0x20 == 0 {
t.Error("overflow flag not set with 9 sprites on a line")
}
}
func TestSpriteOverflowNotSetWith8(t *testing.T) {
p := newSpriteScene()
for i := 0; i < 8; i++ {
setSprite(p, i, 9, 1, 0, uint8(i*12))
}
p.WriteRegister(0x2001, 0x1E)
runFrames(p)
runToDot(p, 50, 0)
if p.ReadRegister(0x2002)&0x20 != 0 {
t.Error("overflow flag set with only 8 sprites")
}
}
func TestSpriteLeftClip(t *testing.T) {
scene := func(mask uint8) *ppu.PPU {
p := newSpriteScene()
setSprite(p, 0, 9, 1, 0, 0)
p.WriteRegister(0x2001, mask)
runFrames(p)
return p
}
checkPixels(t, scene(0x10), []px{{0, 10, black}, {8, 10, black}})
checkPixels(t, scene(0x14), []px{{0, 10, blue}})
}
func TestSpriteHiddenWhenSpritesDisabled(t *testing.T) {
p := newSpriteScene()
setSprite(p, 0, 9, 1, 0, 16)
p.WriteRegister(0x2001, 0x08)
runFrames(p)
checkPixels(t, p, []px{{16, 10, black}})
}
func sprite0Hit(p *ppu.PPU) bool {
return p.ReadRegister(0x2002)&0x40 != 0
}
func TestSprite0HitTiming(t *testing.T) {
p := newSpriteScene()
writeVRAM(p, 0x2002, 1)
setSprite(p, 0, 0, 1, 0, 16)
p.WriteRegister(0x2001, 0x1E)
runFrames(p)
// first overlap is pixel x = 16 on line 1, which is dot 17
runToDot(p, 1, 10)
if sprite0Hit(p) {
t.Error("hit set before the overlap")
}
runToDot(p, 1, 20)
if !sprite0Hit(p) {
t.Error("hit not set after the overlap")
}
runToDot(p, 261, 2)
if sprite0Hit(p) {
t.Error("hit not cleared on the pre-render line")
}
}
func TestSprite0HitNeedsOverlap(t *testing.T) {
p := newSpriteScene()
writeVRAM(p, 0x2002, 1)
setSprite(p, 0, 0, 1, 0, 100)
p.WriteRegister(0x2001, 0x1E)
runFrames(p)
runToDot(p, 50, 0)
if sprite0Hit(p) {
t.Error("hit set without a background pixel under sprite 0")
}
}
func TestSprite0HitOnlyForSprite0(t *testing.T) {
p := newSpriteScene()
writeVRAM(p, 0x2002, 1)
setSprite(p, 1, 0, 1, 0, 16)
p.WriteRegister(0x2001, 0x1E)
runFrames(p)
runToDot(p, 50, 0)
if sprite0Hit(p) {
t.Error("hit set by sprite 1")
}
}
func TestSprite0HitWhenBehindBackground(t *testing.T) {
p := newSpriteScene()
writeVRAM(p, 0x2002, 1)
setSprite(p, 0, 0, 1, 0x20, 16)
p.WriteRegister(0x2001, 0x1E)
runFrames(p)
runToDot(p, 50, 0)
if !sprite0Hit(p) {
t.Error("hit not set for a sprite 0 behind the background")
}
}
func TestSprite0HitRespectsLeftClip(t *testing.T) {
scene := func(mask uint8) *ppu.PPU {
p := newSpriteScene()
writeVRAM(p, 0x2000, 1)
setSprite(p, 0, 0, 1, 0, 0)
p.WriteRegister(0x2001, mask)
runFrames(p)
runToDot(p, 50, 0)
return p
}
if sprite0Hit(scene(0x18)) {
t.Error("hit set inside the clipped left 8 pixels")
}
if !sprite0Hit(scene(0x1E)) {
t.Error("hit not set with the left 8 pixels shown")
}
}
func TestSprite0HitNeverAtX255(t *testing.T) {
p := newSpriteScene()
setSprite(p, 0, 0, 1, 0, 255)
p.WriteRegister(0x2001, 0x1E)
runFrames(p)
runToDot(p, 50, 0)
if sprite0Hit(p) {
t.Error("hit set at x = 255")
}
}
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