gnodraw.gno
9.43 Kb · 287 lines
1// Package gnodraw is a pay-per-pixel collaborative canvas: anyone can paint
2// any pixel of a Width x Height grid in one of 15 colors by sending exactly
3// Price() ugnot per pixel along with the call. Pixels can be repainted by
4// anyone, for the same price. Payments are forwarded to the admin wallet
5// as they arrive, and the admin paints for free.
6//
7// The grid logic lives in gno.land/p/g1v7s3j506wqul2zwt90awgjphpx4ztwga0926f7/canvas/v0; this realm adds the
8// payment guard, the owner controls and the read API used by the web client.
9package gnodraw
10
11import (
12 "chain"
13 "chain/banker"
14 "chain/runtime/unsafe"
15 "strconv"
16 "strings"
17
18 "gno.land/p/g1v7s3j506wqul2zwt90awgjphpx4ztwga0926f7/canvas/v0"
19 "gno.land/p/nt/ufmt/v0"
20)
21
22const (
23 // Width and Height are fixed for the life of this version: changing
24 // them would change the storage layout, so it means a new /vN.
25 // 1250 x 800 is one million pixels in a 16:10 laptop aspect ratio.
26 Width = 1250
27 Height = 800
28
29 // DefaultMaxBatch bounds a single PaintBatch call so one tx cannot blow
30 // the block gas limit or overflow the price arithmetic. The owner can
31 // change it at runtime with SetMaxBatch, up to HardMaxBatch.
32 DefaultMaxBatch = 5000
33 HardMaxBatch = 20000
34
35 // DefaultPrice is the initial price per pixel, in ugnot (0.05 GNOT).
36 DefaultPrice int64 = 50_000
37
38 // DefaultAdmin receives every payment, paints for free and holds the
39 // owner controls. Change it before deploying; TransferOwnership moves
40 // it afterwards.
41 DefaultAdmin = "g1v7s3j506wqul2zwt90awgjphpx4ztwga0926f7"
42
43 Denom = "ugnot"
44)
45
46var (
47 board = canvas.New(Width, Height)
48 price = DefaultPrice
49 maxBatch = DefaultMaxBatch
50 owner = address(DefaultAdmin)
51
52 // Stats.
53 revenue int64 // total ugnot ever paid for pixels
54 paints int64 // number of successful Paint/PaintBatch calls
55
56 // Change tracking, so clients fetch only the rows that moved.
57 // version bumps once per successful paint call; rowVersion holds the
58 // version of the last paint that touched each row (0 = never painted).
59 version int64
60 rowVersion = make([]int64, Height)
61)
62
63// Paint colors one pixel. Send exactly Price() ugnot (nothing for the admin).
64func Paint(cur realm, x, y, color int) {
65 if color <= 0 || color > int(canvas.MaxColor) {
66 panic(canvas.ErrInvalidColor)
67 }
68 paint([]canvas.Pixel{{X: x, Y: y, Color: byte(color)}}, cur)
69}
70
71// PaintBatch colors up to MaxBatchSize() pixels in one call. The argument is
72// "x,y,color;x,y,color;...". Send exactly Price() * count ugnot (nothing
73// for the admin).
74func PaintBatch(cur realm, pixels string) {
75 px, err := canvas.ParsePixels(pixels)
76 if err != nil {
77 panic(err)
78 }
79 paint(px, cur)
80}
81
82// paint takes the realm as its LAST parameter on purpose: a realm first
83// parameter would make it a crossing function and Previous() would then
84// be this realm instead of the user.
85func paint(px []canvas.Pixel, rlm realm) {
86 if !rlm.IsCurrent() {
87 panic("spoofed realm")
88 }
89 // Payment guard: unsafe.OriginSend() describes the coins attached to
90 // the transaction, which only provably landed here when the caller is
91 // a plain user call (no intermediate or ephemeral realm). Keep the two
92 // checks together. unsafe is imported for OriginSend only; caller
93 // identity always comes from the realm handle.
94 if !rlm.Previous().IsUserCall() {
95 panic("must be called directly by a user (maketx call)")
96 }
97 painter := rlm.Previous().Address()
98 n := len(px)
99 if n == 0 {
100 panic("nothing to paint")
101 }
102 if n > maxBatch {
103 panic(ufmt.Sprintf("too many pixels: %d > %d", n, maxBatch))
104 }
105 for _, p := range px {
106 if err := board.Check(p); err != nil {
107 panic(err)
108 }
109 }
110
111 cost := price * int64(n)
112 if painter == owner {
113 cost = 0 // the admin paints for free
114 }
115 if sent := sentUgnot(unsafe.OriginSend()); sent != cost {
116 panic(ufmt.Sprintf("must send exactly %d%s for %d pixel(s), got %d%s", cost, Denom, n, sent, Denom))
117 }
118 if cost > 0 {
119 // Forward the payment to the admin right away, so nothing
120 // accumulates in the realm. BankerTypeOriginSend can only move
121 // what this very message sent, which is exactly cost.
122 bnk := banker.NewBanker(banker.BankerTypeOriginSend, rlm)
123 bnk.SendCoins(rlm.Address(), owner, chain.NewCoins(chain.NewCoin(Denom, cost)))
124 }
125
126 version++
127 for _, p := range px {
128 board.Set(p)
129 rowVersion[p.Y] = version
130 }
131 revenue += cost
132 paints++
133
134 // The pixel list itself is not emitted: event attribute values are
135 // size-capped by the node and a full batch exceeds it. Clients re-read
136 // Rows() after a paint.
137 chain.Emit("Paint",
138 "painter", painter.String(),
139 "count", strconv.Itoa(n),
140 "paid", strconv.Itoa(int(cost))+Denom,
141 )
142}
143
144// sentUgnot returns the ugnot amount in coins and rejects any other denom,
145// so a caller cannot pay with something the realm does not price.
146func sentUgnot(coins chain.Coins) int64 {
147 var amount int64
148 for _, c := range coins {
149 if c.Denom != Denom {
150 panic("only " + Denom + " is accepted")
151 }
152 amount += c.Amount
153 }
154 return amount
155}
156
157// --- owner controls ---
158
159// assertOwner panics unless the verified caller behind rlm is the owner.
160// The realm is deliberately not the first parameter (see paint); the
161// leading blank int is the same idiom gno.land/p/nt/ownable uses.
162func assertOwner(_ int, rlm realm) {
163 if !rlm.IsCurrent() {
164 panic("spoofed realm")
165 }
166 if rlm.Previous().Address() != owner {
167 panic("owner only")
168 }
169}
170
171// SetPrice changes the price per pixel, in ugnot. Zero makes painting free
172// for everyone.
173func SetPrice(cur realm, ugnot int64) {
174 assertOwner(0, cur)
175 if ugnot < 0 {
176 panic("price must not be negative")
177 }
178 price = ugnot
179}
180
181// SetMaxBatch changes the maximum pixels per PaintBatch call, 1..HardMaxBatch.
182func SetMaxBatch(cur realm, n int) {
183 assertOwner(0, cur)
184 if n < 1 || n > HardMaxBatch {
185 panic(ufmt.Sprintf("max batch must be between 1 and %d", HardMaxBatch))
186 }
187 maxBatch = n
188}
189
190// Withdraw sends amount ugnot held by the realm to the given address.
191// Payments are forwarded on arrival, so this only matters for coins sent
192// to the realm outside of a paint call.
193func Withdraw(cur realm, to address, amount int64) {
194 assertOwner(0, cur)
195 if !to.IsValid() {
196 panic("invalid address")
197 }
198 if amount <= 0 {
199 panic("amount must be positive")
200 }
201 bnk := banker.NewBanker(banker.BankerTypeRealmSend, cur)
202 bnk.SendCoins(cur.Address(), to, chain.NewCoins(chain.NewCoin(Denom, amount)))
203}
204
205// TransferOwnership hands the admin role (payments, free painting and the
206// owner controls) to newOwner.
207func TransferOwnership(cur realm, newOwner address) {
208 assertOwner(0, cur)
209 if !newOwner.IsValid() {
210 panic("invalid address")
211 }
212 owner = newOwner
213}
214
215// --- read API (used by the web client through vm/qeval) ---
216
217func GetWidth() int { return Width }
218func GetHeight() int { return Height }
219func Price() int64 { return price }
220func Owner() address { return owner }
221func Painted() int { return board.Painted() }
222func Revenue() int64 { return revenue }
223func Paints() int64 { return paints }
224func MaxBatchSize() int { return maxBatch }
225
226// Pixel returns the color index at (x, y); 0 means never painted.
227func Pixel(x, y int) int { return int(board.Get(x, y)) }
228
229// Rows returns rows [from, to) as one hex digit per pixel, Width digits per
230// row, with no separators. Clients page through the grid with it.
231func Rows(from, to int) string { return board.Rows(from, to) }
232
233// Version is the number of successful paint calls so far. Clients remember
234// it and ask DirtyRows for what changed since.
235func Version() int64 { return version }
236
237// DirtyRows lists the rows painted after version `since`, as "y,y,y" in
238// ascending order. DirtyRows(0) is every row that was ever painted, which
239// is all a fresh client needs to load: the others are blank.
240func DirtyRows(since int64) string {
241 if since < 0 {
242 since = 0
243 }
244 var sb strings.Builder
245 for y, v := range rowVersion {
246 if v <= since {
247 continue
248 }
249 if sb.Len() > 0 {
250 sb.WriteByte(',')
251 }
252 sb.WriteString(strconv.Itoa(y))
253 }
254 return sb.String()
255}
256
257// Palette returns the 16 palette colors as comma-separated CSS hex values,
258// index 0 being the blank color.
259func Palette() string {
260 return strings.Join(canvas.Palette[:], ",")
261}
262
263// Render shows the game stats on gnoweb. The path is ignored.
264func Render(_ string) string {
265 var sb strings.Builder
266 sb.WriteString("# Million Gno\n\n")
267 sb.WriteString("A pay-per-pixel canvas. Pick a color, pay the price, own the pixel until someone repaints it. Payments go to the admin wallet, which paints for free.\n\n")
268 sb.WriteString("| | |\n|---|---|\n")
269 sb.WriteString(ufmt.Sprintf("| Size | %d x %d |\n", Width, Height))
270 sb.WriteString(ufmt.Sprintf("| Price per pixel | %d%s |\n", price, Denom))
271 sb.WriteString(ufmt.Sprintf("| Pixels painted | %d / %d |\n", board.Painted(), Width*Height))
272 sb.WriteString(ufmt.Sprintf("| Paint calls | %d |\n", paints))
273 sb.WriteString(ufmt.Sprintf("| Version | %d |\n", version))
274 sb.WriteString(ufmt.Sprintf("| Revenue | %d%s |\n", revenue, Denom))
275 sb.WriteString(ufmt.Sprintf("| Admin | %s |\n", owner.String()))
276 sb.WriteString("\n## Palette\n\n")
277 for i := 1; i <= int(canvas.MaxColor); i++ {
278 sb.WriteString(ufmt.Sprintf("- %d: `%s`\n", i, canvas.Palette[i]))
279 }
280 sb.WriteString("\n## Paint\n\n")
281 sb.WriteString("- [Paint one pixel](" + Realm + "$help&func=Paint): `Paint(x, y, color)` with `-send <price>ugnot`\n")
282 sb.WriteString("- [Paint a batch](" + Realm + "$help&func=PaintBatch): `PaintBatch(\"x,y,color;x,y,color\")` with `-send <price*count>ugnot`\n")
283 return sb.String()
284}
285
286// Realm is this realm's gnoweb path.
287const Realm = "/r/g1v7s3j506wqul2zwt90awgjphpx4ztwga0926f7/gnodraw/v0"
