void b2VoronoiDiagram::Generate(float32 radius)
{
b2Assert(m_diagram == NULL);
float32 inverseRadius = 1 / radius;
b2Vec2 lower(+b2_maxFloat, +b2_maxFloat);
b2Vec2 upper(-b2_maxFloat, -b2_maxFloat);
for (int32 k = 0; k < m_generatorCount; k++)
{
Generator& g = m_generatorBuffer[k];
lower = b2Min(lower, g.center);
upper = b2Max(upper, g.center);
}
m_countX = 1 + (int32) (inverseRadius * (upper.x - lower.x));
m_countY = 1 + (int32) (inverseRadius * (upper.y - lower.y));
m_diagram = (Generator**)
m_allocator->Allocate(sizeof(Generator*) * m_countX * m_countY);
for (int32 i = 0; i < m_countX * m_countY; i++)
{
m_diagram[i] = NULL;
}
b2StackQueue<b2VoronoiDiagramTask> queue(
m_allocator, 4 * m_countX * m_countX);
for (int32 k = 0; k < m_generatorCount; k++)
{
Generator& g = m_generatorBuffer[k];
g.center = inverseRadius * (g.center - lower);
int32 x = b2Max(0, b2Min((int32) g.center.x, m_countX - 1));
int32 y = b2Max(0, b2Min((int32) g.center.y, m_countY - 1));
queue.Push(b2VoronoiDiagramTask(x, y, x + y * m_countX, &g));
}
while (!queue.Empty())
{
int32 x = queue.Front().m_x;
int32 y = queue.Front().m_y;
int32 i = queue.Front().m_i;
Generator* g = queue.Front().m_generator;
queue.Pop();
if (!m_diagram[i])
{
m_diagram[i] = g;
if (x > 0)
{
queue.Push(b2VoronoiDiagramTask(x - 1, y, i - 1, g));
}
if (y > 0)
{
queue.Push(b2VoronoiDiagramTask(x, y - 1, i - m_countX, g));
}
if (x < m_countX - 1)
{
queue.Push(b2VoronoiDiagramTask(x + 1, y, i + 1, g));
}
if (y < m_countY - 1)
{
queue.Push(b2VoronoiDiagramTask(x, y + 1, i + m_countX, g));
}
}
}
int32 maxIteration = m_countX + m_countY;
for (int32 iteration = 0; iteration < maxIteration; iteration++)
{
for (int32 y = 0; y < m_countY; y++)
{
for (int32 x = 0; x < m_countX - 1; x++)
{
int32 i = x + y * m_countX;
Generator* a = m_diagram[i];
Generator* b = m_diagram[i + 1];
if (a != b)
{
queue.Push(b2VoronoiDiagramTask(x, y, i, b));
queue.Push(b2VoronoiDiagramTask(x + 1, y, i + 1, a));
}
}
}
for (int32 y = 0; y < m_countY - 1; y++)
{
for (int32 x = 0; x < m_countX; x++)
{
int32 i = x + y * m_countX;
Generator* a = m_diagram[i];
Generator* b = m_diagram[i + m_countX];
if (a != b)
{
queue.Push(b2VoronoiDiagramTask(x, y, i, b));
queue.Push(b2VoronoiDiagramTask(x, y + 1, i + m_countX, a));
}
}
}
bool updated = false;
while (!queue.Empty())
{
int32 x = queue.Front().m_x;
int32 y = queue.Front().m_y;
int32 i = queue.Front().m_i;
Generator* k = queue.Front().m_generator;
queue.Pop();
Generator* a = m_diagram[i];
Generator* b = k;
if (a != b)
{
float32 ax = a->center.x - x;
float32 ay = a->center.y - y;
float32 bx = b->center.x - x;
float32 by = b->center.y - y;
float32 a2 = ax * ax + ay * ay;
float32 b2 = bx * bx + by * by;
if (a2 > b2)
{
m_diagram[i] = b;
if (x > 0)
{
queue.Push(b2VoronoiDiagramTask(x - 1, y, i - 1, b));
}
if (y > 0)
{
queue.Push(b2VoronoiDiagramTask(x, y - 1, i - m_countX, b));
}
if (x < m_countX - 1)
{
queue.Push(b2VoronoiDiagramTask(x + 1, y, i + 1, b));
}
if (y < m_countY - 1)
{
queue.Push(b2VoronoiDiagramTask(x, y + 1, i + m_countX, b));
}
updated = true;
}
}
}
if (!updated)
{
break;
}
}
}
void b2VoronoiDiagram::Generate(float32 radius, float32 margin)
{
b2Assert(m_diagram == NULL);
float32 inverseRadius = 1 / radius;
b2Vec2 lower(+b2_maxFloat, +b2_maxFloat);
b2Vec2 upper(-b2_maxFloat, -b2_maxFloat);
for (int32 k = 0; k < m_generatorCount; k++)
{
Generator& g = m_generatorBuffer[k];
if (g.necessary)
{
lower = b2Min(lower, g.center);
upper = b2Max(upper, g.center);
}
}
lower.x -= margin;
lower.y -= margin;
upper.x += margin;
upper.y += margin;
m_countX = 1 + (int32) (inverseRadius * (upper.x - lower.x));
m_countY = 1 + (int32) (inverseRadius * (upper.y - lower.y));
m_diagram = (Generator**)
m_allocator->Allocate(sizeof(Generator*) * m_countX * m_countY);
for (int32 i = 0; i < m_countX * m_countY; i++)
{
m_diagram[i] = NULL;
}
// (4 * m_countX * m_countY) is the queue capacity that is experimentally
// known to be necessary and sufficient for general particle distributions.
b2StackQueue<b2VoronoiDiagramTask> queue(
m_allocator, 4 * m_countX * m_countY);
for (int32 k = 0; k < m_generatorCount; k++)
{
Generator& g = m_generatorBuffer[k];
g.center = inverseRadius * (g.center - lower);
int32 x = (int32) g.center.x;
int32 y = (int32) g.center.y;
if (x >=0 && y >= 0 && x < m_countX && y < m_countY)
{
queue.Push(b2VoronoiDiagramTask(x, y, x + y * m_countX, &g));
}
}
while (!queue.Empty())
{
int32 x = queue.Front().m_x;
int32 y = queue.Front().m_y;
int32 i = queue.Front().m_i;
Generator* g = queue.Front().m_generator;
queue.Pop();
if (!m_diagram[i])
{
m_diagram[i] = g;
if (x > 0)
{
queue.Push(b2VoronoiDiagramTask(x - 1, y, i - 1, g));
}
if (y > 0)
{
queue.Push(b2VoronoiDiagramTask(x, y - 1, i - m_countX, g));
}
if (x < m_countX - 1)
{
queue.Push(b2VoronoiDiagramTask(x + 1, y, i + 1, g));
}
if (y < m_countY - 1)
{
queue.Push(b2VoronoiDiagramTask(x, y + 1, i + m_countX, g));
}
}
}
for (int32 y = 0; y < m_countY; y++)
{
for (int32 x = 0; x < m_countX - 1; x++)
{
int32 i = x + y * m_countX;
Generator* a = m_diagram[i];
Generator* b = m_diagram[i + 1];
if (a != b)
{
queue.Push(b2VoronoiDiagramTask(x, y, i, b));
queue.Push(b2VoronoiDiagramTask(x + 1, y, i + 1, a));
}
}
}
for (int32 y = 0; y < m_countY - 1; y++)
{
for (int32 x = 0; x < m_countX; x++)
{
int32 i = x + y * m_countX;
Generator* a = m_diagram[i];
Generator* b = m_diagram[i + m_countX];
if (a != b)
{
queue.Push(b2VoronoiDiagramTask(x, y, i, b));
queue.Push(b2VoronoiDiagramTask(x, y + 1, i + m_countX, a));
}
}
}
while (!queue.Empty())
{
const b2VoronoiDiagramTask& task = queue.Front();
int32 x = task.m_x;
int32 y = task.m_y;
int32 i = task.m_i;
Generator* k = task.m_generator;
queue.Pop();
Generator* a = m_diagram[i];
Generator* b = k;
if (a != b)
{
float32 ax = a->center.x - x;
float32 ay = a->center.y - y;
float32 bx = b->center.x - x;
float32 by = b->center.y - y;
float32 a2 = ax * ax + ay * ay;
float32 b2 = bx * bx + by * by;
if (a2 > b2)
{
m_diagram[i] = b;
if (x > 0)
{
queue.Push(b2VoronoiDiagramTask(x - 1, y, i - 1, b));
}
if (y > 0)
{
queue.Push(b2VoronoiDiagramTask(x, y - 1, i - m_countX, b));
}
if (x < m_countX - 1)
{
queue.Push(b2VoronoiDiagramTask(x + 1, y, i + 1, b));
}
if (y < m_countY - 1)
{
queue.Push(b2VoronoiDiagramTask(x, y + 1, i + m_countX, b));
}
}
}
}
}
