Prevented some out-of-bounds reading and writing of data

ext/ashton/fast_math.c

@@ -12,7 +12,7 @@ void initialize_fast_math()
     }
 
     // Ensure the cardinal directions are 100% accurate.
-    for (int i = 0; i < 360; i += 90)
+    for (int i = 0; i <= 360; i += 90)
     {
         sin_lookup[i * LOOKUPS_PER_DEGREE] = sin(DEGREES_TO_RADIANS(i));
     }
@@ -22,7 +22,9 @@ float fast_sin_deg(float degrees)
 {
     // Normalize to 0..360 (i.e. 0..2PI)
     degrees = fmod(degrees, 360.0f);
-    if(degrees < 0) degrees += 360.0f;
+    if(degrees < 0.0f) degrees += 360.0f;
 
-    return sin_lookup[(int)(degrees * LOOKUPS_PER_DEGREE)];
+    int index = (int)(degrees * LOOKUPS_PER_DEGREE);
+
+    return sin_lookup[index % NUM_LOOKUP_VALUES];
 }

ext/ashton/fast_math.h

@@ -11,7 +11,10 @@
 #define DEGREES_TO_RADIANS(ANGLE) ((ANGLE - 90) * (M_PI / 180.0f))
 
 #define LOOKUPS_PER_DEGREE 10
-#define NUM_LOOKUP_VALUES (360 * LOOKUPS_PER_DEGREE)
+
+// Enough for values from 0..360 inclusive
+#define NUM_LOOKUP_VALUES ((360 + 1) * LOOKUPS_PER_DEGREE)
+
 #define LOOKUP_PRECISION (1.0f / LOOKUPS_PER_DEGREE)
 
 extern float sin_lookup[NUM_LOOKUP_VALUES];

ext/ashton/particle_emitter.c

@@ -476,44 +476,56 @@ static void update_vbo(ParticleEmitter* emitter)
     // Ensure that drawing order is correct by drawing in order of creation...
 
     // First, we draw all those from after the current, going up to the last one.
-    Particle* first = &emitter->particles[emitter->next_particle_index];
-    Particle* last = &emitter->particles[emitter->max_particles - 1];
-    if(color_changes(emitter))
+    uint num_particles_written;
+    if(emitter->next_particle_index != emitter->max_particles - 1) 
     {
-        write_colors_for_particles(emitter->color_array,
-                                   first, last);
+        Particle* first = &emitter->particles[emitter->next_particle_index];
+        Particle* last = &emitter->particles[emitter->max_particles - 1];
+        if(color_changes(emitter))
+        {
+            write_colors_for_particles(emitter->color_array,
+                                       first, last);
+        }
+        if(texture_changes(emitter))
+        {
+            write_texture_coords_for_particles(emitter->texture_coords_array,
+                                               first, last,
+                                               &emitter->texture_info);
+        }
+        num_particles_written = write_vertices_for_particles(emitter->vertex_array,
+                                                                  first, last,
+                                                                  emitter->width, emitter->height);
     }
-    if(texture_changes(emitter))
+    else
     {
-        write_texture_coords_for_particles(emitter->texture_coords_array,
-                                           first, last,
-                                           &emitter->texture_info);
+        num_particles_written = 0;
     }
-    uint num_particles_written = write_vertices_for_particles(emitter->vertex_array,
-                                                              first, last,
-                                                              emitter->width, emitter->height);
+
     // When we copy the second half of the particles, we want to start writing further on.
     uint offset = num_particles_written * VERTICES_IN_PARTICLE;
 
     // Then go from the first to the current.
-    first = emitter->particles;
-    last = &emitter->particles[emitter->next_particle_index - 1];
-    if(color_changes(emitter))
+    if (emitter->next_particle_index > 0)
     {
-        write_colors_for_particles(&emitter->color_array[offset],
-                                   first, last);
-    }
+        Particle* first = &emitter->particles[0];
+        Particle* last = &emitter->particles[emitter->next_particle_index - 1];
+        if (color_changes(emitter))
+        {
+            write_colors_for_particles(&emitter->color_array[offset],
+                                       first, last);
+        }
 
-    if(texture_changes(emitter))
-    {
-        write_texture_coords_for_particles(&emitter->texture_coords_array[offset],
-                                           first, last,
-                                           &emitter->texture_info);
-    }
+        if (texture_changes(emitter))
+        {
+            write_texture_coords_for_particles(&emitter->texture_coords_array[offset],
+                                               first, last,
+                                               &emitter->texture_info);
+        }
 
-    write_vertices_for_particles(&emitter->vertex_array[offset],
-                                 first, last,
-                                 emitter->width, emitter->height);
+        write_vertices_for_particles(&emitter->vertex_array[offset],
+                                     first, last,
+                                     emitter->width, emitter->height);
+    }
 
     // Upload the data, but only as much as we are actually using.
     glBindBufferARB(GL_ARRAY_BUFFER_ARB, emitter->vbo_id);
@@ -738,8 +750,8 @@ static void update_particle(ParticleEmitter* emitter, Particle* particle,
 
     // Die if out of time, invisible or shrunk to nothing.
     if((particle->time_to_live <= 0) ||
-            (particle->color.alpha < 0) ||
-            (particle->scale < 0))
+            (particle->color.alpha <= 0) ||
+            (particle->scale <= 0))
     {
         particle->time_to_live = 0;
         emitter->count -= 1;