├── snailtracer.png ├── README.md ├── snailtracer.sol └── COPYING /snailtracer.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/karalabe/snailtracer/HEAD/snailtracer.png -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # SnailTracer - Pushing the EVM to its knees 2 | 3 | ![SnailTracer](https://raw.githubusercontent.com/karalabe/snailtracer/master/snailtracer.png) 4 | 5 | # Acknowledgements 6 | 7 | The SnailTracer project is an extended Solidity port of [Kevin Beason's `smallpt`](http://www.kevinbeason.com/smallpt/) 8 | global illumination C++ path tracer. Although it is a complete rewrite that underwent heavy modifications, simplifications 9 | and extensions, none of this would have been possible without Kevin's awesome work and [Dr. David Cline's presentation](https://drive.google.com/file/d/0B8g97JkuSSBwUENiWTJXeGtTOHFmSm51UC01YWtCZw/view). 10 | Thank you! 11 | 12 | # License 13 | 14 | SnailTracer is licensed under the [GNU General Public License v3.0](http://www.gnu.org/licenses/gpl-3.0.en.html), also included in the repository in the COPYING file. 15 | -------------------------------------------------------------------------------- /snailtracer.sol: -------------------------------------------------------------------------------- 1 | contract SnailTracer { 2 | // Image properties for the path tracer 3 | int width; // Width of the image being generated, fixed for life 4 | int height; // Height of the image being generated, fixed for life 5 | bytes buffer; // Buffer to accumulate image traces (ephemeral) 6 | 7 | // Configure the scene for the tracer to render 8 | Ray camera; // Camera position for the image assembly 9 | Vector deltaX; // Horizontal FoV angle increment per image pixel 10 | Vector deltaY; // Vertical FoV andle increment per image pixel 11 | Sphere[] spheres; // Array of shperes defining the scene to render 12 | Triangle[] triangles; // Array of triangles defining the scene to render 13 | 14 | // SnailTracer is the ray tracer constructor to create the scene and pre-calculate 15 | // some constants that are the same throughout the path tracing procedure. 16 | function SnailTracer(int w, int h) { 17 | // Initialize the image parameters 18 | width = w; 19 | height = h; 20 | 21 | // Initialize the rendering parameters 22 | camera = Ray(Vector(50000000, 52000000, 295600000), norm(Vector(0, -42612, -1000000)), 0, false); 23 | deltaX = Vector(width * 513500 / height, 0, 0); 24 | deltaY = div(mul(norm(cross(deltaX, camera.direction)), 513500), 1000000); 25 | 26 | // Initialize the scene bounding boxes 27 | spheres.push(Sphere(100000000000, Vector(100001000000, 40800000, 81600000), Vector(0, 0, 0), Vector(750000, 250000, 250000), Material.Diffuse)); 28 | spheres.push(Sphere(100000000000, Vector(-99901000000, 40800000, 81600000), Vector(0, 0, 0), Vector(250000, 250000, 750000), Material.Diffuse)); 29 | spheres.push(Sphere(100000000000, Vector(50000000, 40800000, 100000000000), Vector(0, 0, 0), Vector(750000, 750000, 750000), Material.Diffuse)); 30 | spheres.push(Sphere(100000000000, Vector(50000000, 40800000, -99830000000), Vector(0, 0, 0), Vector(0, 0, 0), Material.Diffuse)); 31 | spheres.push(Sphere(100000000000, Vector(50000000, 100000000000, 81600000), Vector(0, 0, 0), Vector(750000, 750000, 750000), Material.Diffuse)); 32 | spheres.push(Sphere(100000000000, Vector(50000000, -99918400000, 81600000), Vector(0, 0, 0), Vector(750000, 750000, 750000), Material.Diffuse)); 33 | 34 | // Initiallize the reflective sphere and the light source 35 | spheres.push(Sphere(16500000, Vector(27000000, 16500000, 47000000), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 36 | spheres.push(Sphere(600000000, Vector(50000000, 681330000, 81600000), Vector(12000000, 12000000, 12000000), Vector(0, 0, 0), Material.Diffuse)); 37 | //spheres.push(Sphere(16500000, Vector(73000000, 16500000, 78000000), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Refractive)); 38 | 39 | // Ethereum logo fron triangles 40 | triangles.push(Triangle(Vector(56500000, 25740000, 78000000), Vector(73000000, 25740000, 94500000), Vector(73000000, 49500000, 78000000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 41 | triangles.push(Triangle(Vector(56500000, 23760000, 78000000), Vector(73000000, 0, 78000000), Vector(73000000, 23760000, 94500000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 42 | triangles.push(Triangle(Vector(89500000, 25740000, 78000000), Vector(73000000, 49500000, 78000000), Vector(73000000, 25740000, 94500000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 43 | triangles.push(Triangle(Vector(89500000, 23760000, 78000000), Vector(73000000, 23760000, 94500000), Vector(73000000, 0, 78000000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 44 | 45 | // Ethereum logo back triangles 46 | triangles.push(Triangle(Vector(56500000, 25740000, 78000000), Vector(73000000, 49500000, 78000000), Vector(73000000, 25740000, 61500000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 47 | triangles.push(Triangle(Vector(56500000, 23760000, 78000000), Vector(73000000, 23760000, 61500000), Vector(73000000, 0, 78000000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 48 | triangles.push(Triangle(Vector(89500000, 25740000, 78000000), Vector(73000000, 25740000, 61500000), Vector(73000000, 49500000, 78000000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 49 | triangles.push(Triangle(Vector(89500000, 23760000, 78000000), Vector(73000000, 0, 78000000), Vector(73000000, 23760000, 61500000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 50 | 51 | // Ethereum logo middle rectangles 52 | triangles.push(Triangle(Vector(56500000, 25740000, 78000000), Vector(73000000, 25740000, 61500000), Vector(89500000, 25740000, 78000000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 53 | triangles.push(Triangle(Vector(56500000, 25740000, 78000000), Vector(89500000, 25740000, 78000000), Vector(73000000, 25740000, 94500000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 54 | triangles.push(Triangle(Vector(56500000, 23760000, 78000000), Vector(89500000, 23760000, 78000000), Vector(73000000, 23760000, 61500000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 55 | triangles.push(Triangle(Vector(56500000, 23760000, 78000000), Vector(73000000, 23760000, 94500000), Vector(89500000, 23760000, 78000000), Vector(0, 0, 0), Vector(0, 0, 0), Vector(999000, 999000, 999000), Material.Specular)); 56 | 57 | // Calculate all the triangle surface normals 58 | for (uint i=0; i= 0; y--) { 89 | for (int x = 0; x < width; x++) { 90 | Vector memory color = trace(x, y, spp); 91 | 92 | buffer.push(byte(color.x)); 93 | buffer.push(byte(color.y)); 94 | buffer.push(byte(color.z)); 95 | } 96 | } 97 | return buffer; 98 | } 99 | // Benchmark sets up an ephemeral image configuration and traces a select few 100 | // hand picked pixels to measure EVM execution performance. 101 | function Benchmark() constant returns (byte r, byte g, byte b) { 102 | // Configure the scene for benchmarking 103 | width = 1024; height = 768; 104 | 105 | deltaX = Vector(width * 513500 / height, 0, 0); 106 | deltaY = div(mul(norm(cross(deltaX, camera.direction)), 513500), 1000000); 107 | 108 | // Trace a few pixels and collect their colors (sanity check) 109 | Vector memory color; 110 | 111 | color = add(color, trace(512, 384, 8)); // Flat diffuse surface, opposite wall 112 | color = add(color, trace(325, 540, 8)); // Reflective surface mirroring left wall 113 | color = add(color, trace(600, 600, 8)); // Refractive surface reflecting right wall 114 | color = add(color, trace(522, 524, 8)); // Reflective surface mirroring the refractive surface reflecting the light 115 | color = div(color, 4); 116 | 117 | return (byte(color.x), byte(color.y), byte(color.z)); 118 | } 119 | // trace executes the path tracing for a single pixel of the result image and 120 | // returns the RGB color vector normalized to [0, 256) value range. 121 | function trace(int x, int y, int spp) internal returns (Vector color) { 122 | seed = uint32(y * width + x); // Deterministic image irrelevant of render chunks 123 | 124 | delete(color); 125 | for (int k=0; k 1000000) { return 1000000; } 143 | return x; 144 | } 145 | // Square root calculation based on the Babylonian method 146 | function sqrt(int x) internal returns (int y) { 147 | int z = (x + 1) / 2; 148 | y = x; 149 | while (z < y) { 150 | y = z; 151 | z = (x/z + z) / 2; 152 | } 153 | } 154 | // Sine calculation based on Taylor series expansion. 155 | function sin(int x) internal returns (int y) { 156 | // Ensure x is between [0, 2PI) (Taylor expansion is picky with large numbers) 157 | while (x < 0) { 158 | x += 6283184; 159 | } 160 | while (x >= 6283184) { 161 | x -= 6283184; 162 | } 163 | // Calculate the sin based on the Taylor series 164 | int s = 1; int n = x; int d = 1; int f = 2; 165 | while (n > d) { 166 | y += s * n / d; 167 | n = n * x * x / 1000000 / 1000000; 168 | d *= f * (f + 1); 169 | s *= -1; 170 | f += 2; 171 | } 172 | } 173 | // Cosine calculation based on sine and Pythagorean identity. 174 | function cos(int x) internal returns (int) { 175 | int s = sin(x); return sqrt(1000000000000 - s*s); 176 | } 177 | // Abs returns the absolute value of x. 178 | function abs(int x) internal returns (int) { 179 | if (x > 0) { 180 | return x; 181 | } 182 | return -x; 183 | } 184 | // Vector definition and operations 185 | struct Vector { 186 | int x; int y; int z; 187 | } 188 | 189 | function add(Vector u, Vector v) internal returns (Vector) { 190 | return Vector(u.x+v.x, u.y+v.y, u.z+v.z); 191 | } 192 | function sub(Vector u, Vector v) internal returns (Vector) { 193 | return Vector(u.x-v.x, u.y-v.y, u.z-v.z); 194 | } 195 | function mul(Vector v, int m) internal returns (Vector) { 196 | return Vector(m*v.x, m*v.y, m*v.z); 197 | } 198 | function mul(Vector u, Vector v) internal returns (Vector) { 199 | return Vector(u.x*v.x, u.y*v.y, u.z*v.z); 200 | } 201 | function div(Vector v, int d) internal returns (Vector) { 202 | return Vector(v.x/d, v.y/d, v.z/d); 203 | } 204 | function dot(Vector u, Vector v) internal returns (int) { 205 | return u.x*v.x + u.y*v.y + u.z*v.z; 206 | } 207 | function cross(Vector u, Vector v) internal returns (Vector) { 208 | return Vector(u.y*v.z - u.z*v.y, u.z*v.x - u.x*v.z, u.x*v.y - u.y*v.x); 209 | } 210 | function norm(Vector v) internal returns (Vector) { 211 | int length = sqrt(v.x*v.x + v.y*v.y + v.z*v.z); 212 | return Vector(v.x * 1000000 / length, v.y * 1000000 / length, v.z * 1000000 / length); 213 | } 214 | function clamp(Vector v) internal returns (Vector) { 215 | return Vector(clamp(v.x), clamp(v.y), clamp(v.z)); 216 | } 217 | // Ray is a parametric line with an origin and a direction. 218 | struct Ray { 219 | Vector origin; 220 | Vector direction; 221 | int depth; 222 | bool refract; 223 | } 224 | // Material is the various types of light-altering surfaces 225 | enum Material { Diffuse, Specular, Refractive } 226 | 227 | // Primitive is the various types of geometric primitives 228 | enum Primitive { Sphere, Triangle } 229 | 230 | // Sphere is a physical object to intersect the light rays with 231 | struct Sphere { 232 | int radius; 233 | Vector position; 234 | Vector emission; 235 | Vector color; 236 | Material reflection; 237 | } 238 | 239 | // Triangle is a physical object to intersect the light rays with 240 | struct Triangle { 241 | Vector a; 242 | Vector b; 243 | Vector c; 244 | Vector normal; 245 | Vector emission; 246 | Vector color; 247 | Material reflection; 248 | } 249 | 250 | // intersect calculates the intersection of a ray with a sphere, returning the 251 | // distance till the first intersection point or zero in case of no intersection. 252 | function intersect(Sphere s, Ray r) internal returns (int) { 253 | Vector memory op = sub(s.position, r.origin); 254 | 255 | int b = dot(op, r.direction) / 1000000; 256 | int det = b*b - dot(op, op) + s.radius*s.radius; 257 | 258 | // Bail out if ray misses the sphere 259 | if (det < 0) { 260 | return 0; 261 | } 262 | // Calculate the closer intersection point 263 | det = sqrt(det); 264 | if (b - det > 1000) { 265 | return b - det; 266 | } 267 | if (b + det > 1000) { 268 | return b + det; 269 | } 270 | return 0; 271 | } 272 | function intersect(Triangle t, Ray r) internal returns (int) { 273 | Vector memory e1 = sub(t.b, t.a); 274 | Vector memory e2 = sub(t.c, t.a); 275 | 276 | Vector memory p = cross(r.direction, e2); 277 | 278 | // Bail out if ray is is parallel to the triangle 279 | int det = dot(e1, p) / 1000000; 280 | if (det > -1000 && det < 1000) { 281 | return 0; 282 | } 283 | // Calculate and test the 'u' parameter 284 | Vector memory d = sub(r.origin, t.a); 285 | 286 | int u = dot(d, p) / det; 287 | if(u < 0 || u > 1000000) { 288 | return 0; 289 | } 290 | // Calculate and test the 'v' parameter 291 | Vector memory q = cross(d, e1); 292 | 293 | int v = dot(r.direction, q) / det; 294 | if(v < 0 || u + v > 1000000) { 295 | return 0; 296 | } 297 | // Calculate and return the distance 298 | int dist = dot(e2, q) / det; 299 | if (dist < 1000) { 300 | return 0; 301 | } 302 | return dist; 303 | } 304 | function radiance(Ray ray) internal returns (Vector) { 305 | // Place a limit on the depth to prevent stack overflows 306 | if (ray.depth > 10) { 307 | return Vector(0, 0, 0); 308 | } 309 | // Find the closest object of intersection 310 | int dist; Primitive p; uint id; (dist, p, id) = traceray(ray); 311 | if (dist == 0) { 312 | return Vector(0, 0, 0); 313 | } 314 | Sphere memory sphere; 315 | Triangle memory triangle; 316 | Vector memory color; 317 | Vector memory emission; 318 | 319 | if (p == Primitive.Sphere) { 320 | sphere = spheres[id]; 321 | color = sphere.color; 322 | emission = sphere.emission; 323 | } else { 324 | triangle = triangles[id]; 325 | color = triangle.color; 326 | emission = triangle.emission; 327 | } 328 | // After a number of reflections, randomly stop radiance calculation 329 | int ref = 1; 330 | if (color.z > ref) { 331 | ref = color.z; 332 | } 333 | if (color.y > ref) { 334 | ref = color.y; 335 | } 336 | if (color.z > ref) { 337 | ref = color.z; 338 | } 339 | ray.depth++; 340 | if (ray.depth > 5) { 341 | if (rand() % 1000000 < ref) { 342 | color = div(mul(color, 1000000), ref); 343 | } else { 344 | return emission; 345 | } 346 | } 347 | // Calculate the primitive dependent radiance 348 | Vector memory result; 349 | if (p == Primitive.Sphere) { 350 | result = radiance(ray, sphere, dist); 351 | } else { 352 | result = radiance(ray, triangle, dist); 353 | } 354 | return add(emission, div(mul(color, result), 1000000)); 355 | } 356 | function radiance(Ray ray, Sphere obj, int dist) internal returns (Vector) { 357 | // Calculate the sphere intersection point and normal vectors for recursion 358 | Vector memory intersect = add(ray.origin, div(mul(ray.direction, dist), 1000000)); 359 | Vector memory normal = norm(sub(intersect, obj.position)); 360 | 361 | // For diffuse reflectivity 362 | if (obj.reflection == Material.Diffuse) { 363 | if (dot(normal, ray.direction) >= 0) { 364 | normal = mul(normal, -1); 365 | } 366 | return diffuse(ray, intersect, normal); 367 | } else { // For specular reflectivity 368 | return specular(ray, intersect, normal); 369 | } 370 | } 371 | function radiance(Ray ray, Triangle obj, int dist) internal returns (Vector) { 372 | // Calculate the triangle intersection point for refraction 373 | // We're cheating here, we don't have diffuse triangles :P 374 | Vector memory intersect = add(ray.origin, div(mul(ray.direction, dist), 1000000)); 375 | 376 | // Calculate the refractive indices based on whether we're in or out 377 | int nnt = 666666; // (1 air / 1.5 glass) 378 | if (ray.refract) { 379 | nnt = 1500000; // (1.5 glass / 1 air) 380 | } 381 | int ddn = dot(obj.normal, ray.direction) / 1000000; 382 | if (ddn >= 0) { 383 | ddn = -ddn; 384 | } 385 | // If the angle is too shallow, all light is reflected 386 | int cos2t = 1000000000000 - nnt * nnt * (1000000000000 - ddn * ddn) / 1000000000000; 387 | if (cos2t < 0) { 388 | return specular(ray, intersect, obj.normal); 389 | } 390 | return refractive(ray, intersect, obj.normal, nnt, ddn, cos2t); 391 | } 392 | function diffuse(Ray ray, Vector intersect, Vector normal) internal returns (Vector) { 393 | // Generate a random angle and distance from center 394 | int r1 = int(6283184) * (rand() % 1000000) / 1000000; 395 | int r2 = rand() % 1000000; int r2s = sqrt(r2) * 1000; 396 | 397 | // Create orthonormal coordinate frame 398 | Vector memory u; 399 | if (abs(normal.x) > 100000) { 400 | u = Vector(0, 1000000, 0); 401 | } else { 402 | u = Vector(1000000, 0, 0); 403 | } 404 | u = norm(cross(u, normal)); 405 | Vector memory v = norm(cross(normal, u)); 406 | 407 | // Generate the random reflection ray and continue path tracing 408 | u = norm(add(add(mul(u, cos(r1) * r2s / 1000000), mul(v, sin(r1) * r2s / 1000000)), mul(normal, sqrt(1000000 - r2) * 1000))); 409 | return radiance(Ray(intersect, u, ray.depth, ray.refract)); 410 | } 411 | function specular(Ray ray, Vector intersect, Vector normal) internal returns (Vector) { 412 | Vector memory reflection = norm(sub(ray.direction, mul(normal, 2 * dot(normal, ray.direction) / 1000000))); 413 | return radiance(Ray(intersect, reflection, ray.depth, ray.refract)); 414 | } 415 | function refractive(Ray ray, Vector intersect, Vector normal, int nnt, int ddn, int cos2t) internal returns (Vector) { 416 | // Calculate the refraction rays for fresnel effects 417 | int sign = -1; if (ray.refract) { sign = 1; } 418 | Vector memory refraction = norm(div(sub(mul(ray.direction, nnt), mul(normal, sign * (ddn * nnt / 1000000 + sqrt(cos2t)))), 1000000)); 419 | 420 | // Calculate the fresnel probabilities 421 | int c = 1000000 + ddn; 422 | if (!ray.refract) { 423 | c = 1000000 - dot(refraction, normal) / 1000000; 424 | } 425 | int re = 40000 + (1000000 - 40000) * c * c * c * c * c / 1000000000000000000000000000000; 426 | 427 | // Split a direct hit, otherwise trace only one ray 428 | if (ray.depth <= 2) { 429 | refraction = mul(radiance(Ray(intersect, refraction, ray.depth, !ray.refract)), 1000000 - re); // Reuse refraction variable (lame) 430 | refraction = add(refraction, mul(specular(ray, intersect, normal), re)); 431 | return div(refraction, 1000000); 432 | } 433 | if (rand() % 1000000 < 250000 + re / 2) { 434 | return div(mul(specular(ray, intersect, normal), re), 250000 + re / 2); 435 | } 436 | return div(mul(radiance(Ray(intersect, refraction, ray.depth, !ray.refract)), 1000000 - re), 750000 - re / 2); 437 | } 438 | // traceray calculates the intersection of a ray with all the objects and 439 | // returns the closest one. 440 | function traceray(Ray ray) internal returns (int, Primitive, uint) { 441 | int dist = 0; Primitive p; uint id; 442 | 443 | // Intersect the ray with all the spheres 444 | for (uint i=0; i 0 && (dist == 0 || d < dist)) { 447 | dist = d; p = Primitive.Sphere; id = i; 448 | } 449 | } 450 | // Intersect the ray with all the triangles 451 | for (i=0; i 0 && (dist == 0 || d < dist)) { 454 | dist = d; p = Primitive.Triangle; id = i; 455 | } 456 | } 457 | return (dist, p, id); 458 | } 459 | } 460 | -------------------------------------------------------------------------------- /COPYING: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2016 Péter Szilágyi. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | --------------------------------------------------------------------------------