void Run(EntityManager& em, CSnakeGame& gsnake) {
CGrid& grid = gsnake.GetGrid();
for (auto a = em.begin(); a != em.end(); a++) {
if (!(*a)->HasComponent<CMotion>() || !(*a)->HasComponent<CHead>()) {
continue;
}
if (!IsInsideGrid(*(*a)->GetComponent<CMotion>(), gsnake.GetGrid().GetGridSize())) {
gsnake.GameOver();
}
}
for (auto a = em.begin(); a != em.end(); a++) {
if ((*a).get() == 0 || !(*a)->HasComponent<CPlayerControlled>()) {
continue;
}
CHead* head_a = (*a)->GetComponent<CHead>();
CMotion* motion_a = (*a)->GetComponent<CMotion>();
for (auto b = em.begin(); b != em.end(); b++) {
if ((*b).get() == 0 || a == b || !(*b)->HasComponent<CMotion>()) {
continue;
}
CMotion* motion_b = (*b)->GetComponent<CMotion>();
if (motion_a->GetCoords() == motion_b->GetCoords()) {
std::pair<int, int> xy = motion_b->GetCoords();
if (grid.Get(xy.first, xy.second) < 0) {
head_a->SetLength(head_a->GetLength() + 1);
xy = grid.EatFood(xy.first, xy.second);
em.MarkAdded(std::unique_ptr<CEntity>(new CFood(xy.first, xy.second)));
em.MarkRemoved(*b);
} else if (grid.Get(xy.first, xy.second) > 0 || (*b)->HasComponent<CHead>()) {
gsnake.GameOver();
}
}
}
}
em.Update();
}
bool VoxelGrid::Trace(const SceneObject* parentObject, Ray* inputRay, IntersectionState* outputIntersection)
{
glm::mat4 spaceTransform(1.f);
if (parentObject) {
spaceTransform = parentObject->GetWorldToObjectMatrix();
}
glm::vec3 rayPos = glm::vec3(spaceTransform * inputRay->GetPosition());
const glm::vec3 rayDir = glm::vec3(spaceTransform * inputRay->GetForwardDirection());
glm::ivec3 step;
for (int i = 0; i < 3; ++i) {
if (std::abs(rayDir[i]) < SMALL_EPSILON) {
step[i] = 0;
} else {
step[i] = (rayDir[i] > SMALL_EPSILON) ? 1 : -1;
}
}
// Implementation of "A Fast Voxel Traversal Algorithm for Ray Tracing" by John Amanatides and Andrew Woo
// Link: http://www.cse.chalmers.se/edu/year/2010/course/TDA361/grid.pdf
glm::ivec3 currentVoxelIndex = GetVoxelForPosition(rayPos, false);
#if DEBUG_VOXEL_GRID
std::cout << "Initial Voxel Position: " << glm::to_string(currentVoxelIndex) << " for " << glm::to_string(rayPos) << " going " << glm::to_string(rayDir) << std::endl;
#endif
// If we aren't currently within the grid, move the ray position such that we are.
if (!IsInsideGrid(currentVoxelIndex)) {
IntersectionState tempState;
if (!boundingBox.Trace(parentObject, inputRay, &tempState)) {
return false;
}
const float dt = tempState.intersectionT + SMALL_EPSILON;
currentVoxelIndex = GetVoxelForPosition(rayPos + rayDir * dt);
}
#if DEBUG_VOXEL_GRID
std::cout << "Final Voxel Position: " << glm::to_string(currentVoxelIndex) << " for " << glm::to_string(rayPos) << " going " << glm::to_string(rayDir) << std::endl;
std::cout << "Scene Bounding: " << glm::to_string(boundingBox.minVertex) << " " << glm::to_string(boundingBox.maxVertex) << std::endl;
std::cout << "Voxel Size: " << glm::to_string(voxelSize) << std::endl;
#endif
while (IsInsideGrid(currentVoxelIndex)) {
#if DEBUG_VOXEL_GRID
std::cout << "Trace Voxel: " << glm::to_string(currentVoxelIndex) << std::endl;
#endif
IntersectionState tempIntersection;
tempIntersection.TestAndCopyLimits(outputIntersection);
bool hitVoxel = grid[currentVoxelIndex[0]][currentVoxelIndex[1]][currentVoxelIndex[2]].Trace(parentObject, inputRay, &tempIntersection);
// Need to verify that the hit position is within the voxel -- otherwise we're looking too far ahead.
const glm::vec3 hitPosition = rayPos + rayDir * tempIntersection.intersectionT;
#if DEBUG_VOXEL_GRID
std::cout << " -- hit position " << glm::to_string(hitPosition) << " " << glm::to_string(GetVoxelForPosition(hitPosition)) << std::endl;
#endif
if (hitVoxel && GetVoxelForPosition(hitPosition) == currentVoxelIndex) {
if (outputIntersection) {
*outputIntersection = tempIntersection;
}
#if DEBUG_VOXEL_GRID
std::cout << " did done hit" << std::endl;
#endif
return true;
}
int minIndex = 0;
float minTMax = 0.f;
FindClosestVoxelSide(minIndex, minTMax, currentVoxelIndex, step, rayPos, rayDir);
assert(minIndex >= 0);
currentVoxelIndex[minIndex] += step[minIndex];
#if DEBUG_VOXEL_GRID
std::cout << " -- next voxel: " << glm::to_string(currentVoxelIndex) << " " << minIndex << " " << minTMax << std::endl;
#endif
}
return false;
}
