diff --git a/src/main.cu b/src/main.cu
index 2fb4f75..15da3a1 100644
--- a/src/main.cu
+++ b/src/main.cu
@@ -56,13 +56,19 @@ __device__ vec3 color(const ray& r, hitable **world, curandState *local_rand_sta
     return vec3(0, 0, 0);
 }
 
+__global__ void rand_init(curandState *rand_state) {
+    if (threadIdx.x == 0 && threadIdx.y == 0) {
+        curand_init(2002, 0, 0, rand_state);
+    }
+}
+
 __global__ void render_init(int max_x, int max_y, curandState *rand_state) {
     int x = threadIdx.x + blockIdx.x * blockDim.x;
     int y = threadIdx.y + blockIdx.y * blockDim.y;
     if ((x >= max_x) || (y >=  max_y)) return;
     int pixel_idx = y*max_x + x;
 
-    curand_init(2002, pixel_idx, 0, &rand_state[pixel_idx]);
+    curand_init(2002+pixel_idx, 0, 0, &rand_state[pixel_idx]);
 }
 
 __global__ void render(vec3 *fb,
@@ -93,31 +99,59 @@ __global__ void render(vec3 *fb,
     fb[pixel_idx] = col;
 }
 
-__global__ void create_world(hitable **d_list, int d_list_size, hitable **d_world, camera **d_camera, int nx, int ny) {
-    if (threadIdx.x == 0 && blockIdx.y == 0) {
-        d_list[0] = new sphere(vec3( 0,    0  , -1),  0.5, new lambertian(vec3(0.1, 0.2, 0.5)));
-        d_list[1] = new sphere(vec3( 0, -100.5, -1),  100, new lambertian(vec3(0.8, 0.8, 0.0)));
-        d_list[2] = new sphere(vec3( 1,    0  , -1),  0.5, new metal(vec3(0.8, 0.6, 0.2), 0.0));
-        d_list[3] = new sphere(vec3(-1,    0  , -1),  0.5, new dielectric(1.5));
-        d_list[4] = new sphere(vec3(-1,    0  , -1), -0.45, new dielectric(1.5));
-        *d_world  = new hitable_list(d_list, d_list_size);
+__global__ void create_world(hitable **d_list, int d_list_size, hitable **d_world, camera **d_camera, int nx, int ny, curandState *rand_state) {
+    if (!(threadIdx.x == 0 && blockIdx.y == 0)) return;
 
-        vec3 lookfrom(3,3,2);
-        vec3 lookat(0,0,-1);
-        float dist_to_focus = (lookfrom-lookat).length();
-        float aperture = 2.0f;
-        *d_camera = new camera(lookfrom, lookat,
-                                vec3(0,1,0),
-                                20.0,
-                                float(nx)/float(ny),
-                                aperture,
-                                dist_to_focus);
+    curandState local_rand_state = *rand_state;
+    d_list[0] = new sphere(vec3(0, -1000, -1), 1000, new lambertian(vec3(0.5, 0.5, 0.5)));
+
+    #define RND() curand_uniform(&local_rand_state)
+
+    int idx = 1;
+    for (int a = -11; a < 11; a++) {
+        for (int b = -11; b < 11; b++) {
+            float choose_mat = RND();
+            vec3 center(a + RND(), 0.2, b + RND());
+            material *mat;
+            if (choose_mat < 0.8f) {
+                mat = new lambertian(vec3(RND()*RND(), RND()*RND(), RND()*RND()));
+            } else if (choose_mat < 0.95f) {
+                mat = new metal(vec3(0.5f*(1.0f+RND()), 0.5f*(1.0f+RND()), 0.5f*(1.0f+RND())), 0.5f*RND());
+            } else {
+                mat = new dielectric(1.5);
+            }
+            d_list[idx++] = new sphere(center, 0.2, mat);
+        }
     }
+
+    #undef RND
+
+    d_list[idx++] = new sphere(vec3(0, 1,0),  1.0, new dielectric(1.5));
+    d_list[idx++] = new sphere(vec3(-4, 1, 0), 1.0, new lambertian(vec3(0.4, 0.2, 0.1)));
+    d_list[idx++] = new sphere(vec3(4, 1, 0),  1.0, new metal(vec3(0.7, 0.6, 0.5), 0.0));
+    *rand_state = local_rand_state;
+
+    assert(d_list_size == idx);
+    *d_world  = new hitable_list(d_list, d_list_size);
+
+    vec3 lookfrom(13,2,3);
+    vec3 lookat(0,0,0);
+    float dist_to_focus = 10.0; // (lookfrom-lookat).length();
+    float aperture = 0.1f;
+    *d_camera = new camera(
+        lookfrom,
+        lookat,
+        vec3(0,1,0),
+        30.0,
+        float(nx)/float(ny),
+        aperture,
+        dist_to_focus
+    );
 }
 
 __global__ void free_world(hitable **d_list, int d_list_size, hitable **d_world, camera **d_camera) {
     for (int i = 0; i < d_list_size; i++) {
-        delete &((sphere*)d_list[i])->mat;
+        delete ((sphere*)d_list[i])->mat;
         delete &d_list[i];
     }
     delete &d_world;
@@ -128,7 +162,7 @@ int main() {
     const char *image_filename = "out.ppm";
     int nx = 1200;
     int ny = 600;
-    int ns = 100;
+    int ns = 20;
     int tx = 16;
     int ty = 16;
 
@@ -145,16 +179,23 @@ int main() {
     // allocate random state
     curandState *d_rand_state;
     checkCudaErrors(cudaMalloc((void **)&d_rand_state, num_pixels*sizeof(curandState)));
+    curandState *d_rand_world_state;
+    checkCudaErrors(cudaMalloc((void **)&d_rand_world_state, num_pixels*sizeof(curandState)));
+
+    // Initialize world rand state
+    rand_init<<<1,1>>>(d_rand_world_state);
+    checkCudaErrors(cudaGetLastError());
+    checkCudaErrors(cudaDeviceSynchronize());
 
     // populate world
     hitable **d_list;
-    int d_list_size = 5;
+    int d_list_size = 22*22 + 1 + 3;
     checkCudaErrors(cudaMalloc((void **)&d_list, d_list_size*sizeof(hitable *)));
     hitable **d_world;
     checkCudaErrors(cudaMalloc((void **)&d_world, sizeof(hitable *)));
     camera **d_camera;
     checkCudaErrors(cudaMalloc((void **)&d_camera, sizeof(camera *)));
-    create_world<<<1,1>>>(d_list, d_list_size, d_world, d_camera, nx, ny);
+    create_world<<<1,1>>>(d_list, d_list_size, d_world, d_camera, nx, ny, d_rand_world_state);
     checkCudaErrors(cudaGetLastError());
     checkCudaErrors(cudaDeviceSynchronize());
 
@@ -206,6 +247,7 @@ int main() {
     checkCudaErrors(cudaFree(d_world));
     checkCudaErrors(cudaFree(d_camera));
     checkCudaErrors(cudaFree(d_rand_state));
+    checkCudaErrors(cudaFree(d_rand_world_state));
     checkCudaErrors(cudaFree(fb));
 
     cudaDeviceReset();