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Cleaned up Bresenham line in TLine and TEdgeManager.

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This commit is contained in:
Muzychenko Andrey 2022-05-17 12:36:46 +03:00
parent 2d2ca0ab2a
commit 0cb75ecf7f
2 changed files with 83 additions and 227 deletions
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180
SpaceCadetPinball/TEdgeManager.cpp
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@ -14,11 +14,11 @@ TEdgeManager::TEdgeManager(float posX, float posY, float width, float height)
Y = posY; Y = posY;
MaxBoxX = 10; MaxBoxX = 10;
MaxBoxY = 15; MaxBoxY = 15;
AdvanceX = width / 10.0f; AdvanceX = width / static_cast<float>(MaxBoxX);
AdvanceY = height / 15.0f; AdvanceY = height / static_cast<float>(MaxBoxY);
AdvanceXInv = 1.0f / AdvanceX; AdvanceXInv = 1.0f / AdvanceX;
AdvanceYInv = 1.0f / AdvanceY; AdvanceYInv = 1.0f / AdvanceY;
BoxArray = new TEdgeBox[150]; BoxArray = new TEdgeBox[MaxBoxX * MaxBoxY];
} }
TEdgeManager::~TEdgeManager() TEdgeManager::~TEdgeManager()
@ -48,18 +48,26 @@ int TEdgeManager::increment_box_y(int y)
void TEdgeManager::add_edge_to_box(int x, int y, TEdgeSegment* edge) void TEdgeManager::add_edge_to_box(int x, int y, TEdgeSegment* edge)
{ {
BoxArray[x + y * MaxBoxX].EdgeList.push_back(edge); assertm((unsigned)x < (unsigned)MaxBoxX && (unsigned)y < (unsigned)MaxBoxY, "Box coordinates out of range");
auto& list = BoxArray[x + y * MaxBoxX].EdgeList;
assertm(std::find(list.begin(), list.end(), edge) == list.end(), "Duplicate inserted into box");
list.push_back(edge);
} }
void TEdgeManager::add_field_to_box(int x, int y, field_effect_type* field) void TEdgeManager::add_field_to_box(int x, int y, field_effect_type* field)
{ {
BoxArray[x + y * MaxBoxX].FieldList.push_back(field); assertm((unsigned)x < (unsigned)MaxBoxX && (unsigned)y < (unsigned)MaxBoxY, "Box coordinates out of range");
auto& list = BoxArray[x + y * MaxBoxX].FieldList;
assertm(std::find(list.begin(), list.end(), field) == list.end(), "Duplicate inserted into box");
list.push_back(field);
} }
int TEdgeManager::TestGridBox(int x, int y, float* distPtr, TEdgeSegment** edgeDst, ray_type* ray, TBall* ball, int TEdgeManager::TestGridBox(int x, int y, float* distPtr, TEdgeSegment** edgeDst, ray_type* ray, TBall* ball,
int edgeIndex) int edgeIndex)
{ {
if (x >= 0 && x < 10 && y >= 0 && y < 15) if (x >= 0 && x < MaxBoxX && y >= 0 && y < MaxBoxY)
{ {
TEdgeBox* edgeBox = &BoxArray[x + y * MaxBoxX]; TEdgeBox* edgeBox = &BoxArray[x + y * MaxBoxX];
TEdgeSegment** edgePtr = &EdgeArray[edgeIndex]; TEdgeSegment** edgePtr = &EdgeArray[edgeIndex];
@ -111,158 +119,84 @@ float TEdgeManager::FindCollisionDistance(ray_type* ray, TBall* ball, TEdgeSegme
auto distance = 1000000000.0f; auto distance = 1000000000.0f;
auto edgeIndex = 0; auto edgeIndex = 0;
auto rayX = ray->Origin.X; auto x0 = ray->Origin.X;
auto rayY = ray->Origin.Y; auto y0 = ray->Origin.Y;
auto rayBoxX = box_x(rayX); auto x1 = ray->Direction.X * ray->MaxDistance + ray->Origin.X;
auto rayBoxY = box_y(rayY); auto y1 = ray->Direction.Y * ray->MaxDistance + ray->Origin.Y;
auto rayEndX = ray->Direction.X * ray->MaxDistance + ray->Origin.X; auto xBox0 = box_x(x0);
auto rayEndY = ray->Direction.Y * ray->MaxDistance + ray->Origin.Y; auto yBox0 = box_y(y0);
auto rayEndBoxX = box_x(rayEndX); auto xBox1 = box_x(x1);
auto rayEndBoxY = box_y(rayEndY); auto yBox1 = box_y(y1);
auto rayDirX = rayX >= rayEndX ? -1 : 1; auto dirX = x0 >= x1 ? -1 : 1;
auto rayDirY = rayY >= rayEndY ? -1 : 1; auto dirY = y0 >= y1 ? -1 : 1;
if (rayBoxY == rayEndBoxY) if (yBox0 == yBox1)
{ {
if (rayDirX == 1) if (dirX == 1)
{ {
for (auto indexX = rayBoxX; indexX <= rayEndBoxX; indexX++) for (auto indexX = xBox0; indexX <= xBox1; indexX++)
{ {
edgeIndex = TestGridBox(indexX, rayBoxY, &distance, edge, ray, ball, edgeIndex); edgeIndex = TestGridBox(indexX, yBox0, &distance, edge, ray, ball, edgeIndex);
} }
} }
else else
{ {
for (auto indexX = rayBoxX; indexX >= rayEndBoxX; indexX--) for (auto indexX = xBox0; indexX >= xBox1; indexX--)
{ {
edgeIndex = TestGridBox(indexX, rayBoxY, &distance, edge, ray, ball, edgeIndex); edgeIndex = TestGridBox(indexX, yBox0, &distance, edge, ray, ball, edgeIndex);
} }
} }
} }
else if (rayBoxX == rayEndBoxX) else if (xBox0 == xBox1)
{ {
if (rayDirY == 1) if (dirY == 1)
{ {
for (auto indexY = rayBoxY; indexY <= rayEndBoxY; indexY++) for (auto indexY = yBox0; indexY <= yBox1; indexY++)
{ {
edgeIndex = TestGridBox(rayBoxX, indexY, &distance, edge, ray, ball, edgeIndex); edgeIndex = TestGridBox(xBox0, indexY, &distance, edge, ray, ball, edgeIndex);
} }
} }
else else
{ {
for (auto indexY = rayBoxY; indexY >= rayEndBoxY; indexY--) for (auto indexY = yBox0; indexY >= yBox1; indexY--)
{ {
edgeIndex = TestGridBox(rayBoxX, indexY, &distance, edge, ray, ball, edgeIndex); edgeIndex = TestGridBox(xBox0, indexY, &distance, edge, ray, ball, edgeIndex);
} }
} }
} }
else else
{ {
auto rayDyDX = (rayY - rayEndY) / (rayX - rayEndX); edgeIndex = TestGridBox(xBox0, yBox0, &distance, edge, ray, ball, 0);
auto indexX = rayBoxX;
auto indexY = rayBoxY; // Bresenham line formula: y = dYdX * (x - x0) + y0; dYdX = (y0 - y1) / (x0 - x1)
auto bresIndexX = rayBoxX + 1; auto dyDx = (y0 - y1) / (x0 - x1);
auto bresIndexY = rayBoxY + 1; // Precompute constant part: dYdX * (-x0) + y0
auto bresXAdd = rayY - rayDyDX * rayX; auto precomp = -x0 * dyDx + y0;
edgeIndex = TestGridBox(rayBoxX, rayBoxY, &distance, edge, ray, ball, 0); // X and Y indexes are offset by one when going forwards, not sure why
if (rayDirX == 1) auto xBias = dirX == 1 ? 1 : 0, yBias = dirY == 1 ? 1 : 0;
for (auto indexX = xBox0, indexY = yBox0; indexX != xBox1 || indexY != yBox1;)
{ {
if (rayDirY == 1) // Calculate y from indexY and from line formula
auto yDiscrete = (indexY + yBias) * AdvanceY + Y;
auto ylinear = ((indexX + xBias) * AdvanceX + X) * dyDx + precomp;
if (dirY == 1 ? ylinear >= yDiscrete : ylinear <= yDiscrete)
{ {
do // Advance indexY when discrete value is ahead/behind
{ // Advance indexX when discrete value matches linear value
auto yCoord = bresIndexY * AdvanceY + Y; indexY += dirY;
auto xCoord = (bresIndexX * AdvanceX + X) * rayDyDX + bresXAdd; if (ylinear == yDiscrete)
if (xCoord >= yCoord) indexX += dirX;
{
if (xCoord == yCoord)
{
++indexX;
++bresIndexX;
}
++indexY;
++bresIndexY;
} }
else else
{ {
++indexX; // Advance indexX otherwise
++bresIndexX; indexX += dirX;
} }
edgeIndex = TestGridBox(indexX, indexY, &distance, edge, ray, ball, edgeIndex); edgeIndex = TestGridBox(indexX, indexY, &distance, edge, ray, ball, edgeIndex);
} }
while (indexX < rayEndBoxX || indexY < rayEndBoxY);
}
else
{
do
{
auto yCoord = indexY * AdvanceY + Y;
auto xCoord = (bresIndexX * AdvanceX + X) * rayDyDX + bresXAdd;
if (xCoord <= yCoord)
{
if (xCoord == yCoord)
{
++indexX;
++bresIndexX;
}
--indexY;
}
else
{
++indexX;
++bresIndexX;
}
edgeIndex = TestGridBox(indexX, indexY, &distance, edge, ray, ball, edgeIndex);
}
while (indexX < rayEndBoxX || indexY > rayEndBoxY);
}
}
else
{
if (rayDirY == 1)
{
do
{
auto yCoord = bresIndexY * AdvanceY + Y;
auto xCoord = (indexX * AdvanceX + X) * rayDyDX + bresXAdd;
if (xCoord >= yCoord)
{
if (xCoord == yCoord)
--indexX;
++indexY;
++bresIndexY;
}
else
{
--indexX;
}
edgeIndex = TestGridBox(indexX, indexY, &distance, edge, ray, ball, edgeIndex);
}
while (indexX > rayEndBoxX || indexY < rayEndBoxY);
}
else
{
do
{
auto yCoord = indexY * AdvanceY + Y;
auto xCoord = (indexX * AdvanceX + X) * rayDyDX + bresXAdd;
if (xCoord <= yCoord)
{
if (xCoord == yCoord)
--indexX;
--indexY;
}
else
{
--indexX;
}
edgeIndex = TestGridBox(indexX, indexY, &distance, edge, ray, ball, edgeIndex);
}
while (indexX > rayEndBoxX || indexY > rayEndBoxY);
}
}
} }

126
SpaceCadetPinball/TLine.cpp
View File

@ -79,123 +79,45 @@ void TLine::place_in_grid()
{ {
if (dirY == 1) if (dirY == 1)
{ {
if (yBox0 <= yBox1) while (yBox0 <= yBox1)
{
do
edgeMan->add_edge_to_box(xBox0, yBox0++, this); edgeMan->add_edge_to_box(xBox0, yBox0++, this);
while (yBox0 <= yBox1);
} }
} else
else if (yBox0 >= yBox1)
{ {
do while (yBox0 >= yBox1)
edgeMan->add_edge_to_box(xBox0, yBox0--, this); edgeMan->add_edge_to_box(xBox0, yBox0--, this);
while (yBox0 >= yBox1);
} }
} }
else else
{ {
float yCoord, xCoord;
int indexX1 = xBox0, indexY1 = yBox0;
int bresIndexX = xBox0 + 1, bresIndexY = yBox0 + 1;
auto bresDyDx = (Y0 - Y1) / (X0 - X1);
auto bresXAdd = Y0 - bresDyDx * X0;
edgeMan->add_edge_to_box(xBox0, yBox0, this); edgeMan->add_edge_to_box(xBox0, yBox0, this);
if (dirX == 1)
// Bresenham line formula: y = dYdX * (x - x0) + y0; dYdX = (y0 - y1) / (x0 - x1)
auto dyDx = (Y0 - Y1) / (X0 - X1);
// Precompute constant part: dYdX * (-x0) + y0
auto precomp = -X0 * dyDx + Y0;
// X and Y indexes are offset by one when going forwards, not sure why
auto xBias = dirX == 1 ? 1 : 0, yBias = dirY == 1 ? 1 : 0;
for (auto indexX = xBox0, indexY = yBox0; indexX != xBox1 || indexY != yBox1;)
{ {
if (dirY == 1) // Calculate y from indexY and from line formula
auto yDiscrete = (indexY + yBias) * edgeMan->AdvanceY + edgeMan->Y;
auto ylinear = ((indexX + xBias) * edgeMan->AdvanceX + edgeMan->X) * dyDx + precomp;
if (dirY == 1 ? ylinear >= yDiscrete : ylinear <= yDiscrete)
{ {
do // Advance indexY when discrete value is ahead/behind
{ // Advance indexX when discrete value matches linear value
yCoord = bresIndexY * edgeMan->AdvanceY + edgeMan->Y; indexY += dirY;
xCoord = (bresIndexX * edgeMan->AdvanceX + edgeMan->X) * bresDyDx + bresXAdd; if (ylinear == yDiscrete)
if (xCoord >= yCoord) indexX += dirX;
{
if (xCoord == yCoord)
{
++indexX1;
++bresIndexX;
}
++indexY1;
++bresIndexY;
} }
else else
{ {
++indexX1; // Advance indexX otherwise
++bresIndexX; indexX += dirX;
}
edgeMan->add_edge_to_box(indexX1, indexY1, this);
}
while (indexX1 != xBox1 || indexY1 != yBox1);
}
else
{
do
{
yCoord = indexY1 * edgeMan->AdvanceY + edgeMan->Y;
xCoord = (bresIndexX * edgeMan->AdvanceX + edgeMan->X) * bresDyDx + bresXAdd;
if (xCoord <= yCoord)
{
if (xCoord == yCoord)
{
++indexX1;
++bresIndexX;
}
--indexY1;
}
else
{
++indexX1;
++bresIndexX;
}
edgeMan->add_edge_to_box(indexX1, indexY1, this);
}
while (indexX1 != xBox1 || indexY1 != yBox1);
}
}
else
{
if (dirY == 1)
{
do
{
xCoord = bresIndexY * edgeMan->AdvanceY + edgeMan->Y;
yCoord = (indexX1 * edgeMan->AdvanceX + edgeMan->X) * bresDyDx + bresXAdd;
if (yCoord >= xCoord)
{
if (yCoord == xCoord)
--indexX1;
++indexY1;
++bresIndexY;
}
else
{
--indexX1;
}
edgeMan->add_edge_to_box(indexX1, indexY1, this);
}
while (indexX1 != xBox1 || indexY1 != yBox1);
}
else
{
do
{
yCoord = indexY1 * edgeMan->AdvanceY + edgeMan->Y;
xCoord = (indexX1 * edgeMan->AdvanceX + edgeMan->X) * bresDyDx + bresXAdd;
if (xCoord <= yCoord)
{
if (xCoord == yCoord)
--indexX1;
--indexY1;
}
else
{
--indexX1;
}
edgeMan->add_edge_to_box(indexX1, indexY1, this);
}
while (indexX1 != xBox1 || indexY1 != yBox1);
} }
edgeMan->add_edge_to_box(indexX, indexY, this);
} }
} }
} }