traverseGridSegmentFloat()

template<typename GridVisitor>

void fl::traverseGridSegmentFloat ( const vec2f & start, const vec2f & end, GridVisitor & visitor )

inline

Traverse a grid segment using floating point arithmetic.

Traverse a grid segment using fixed-point 8.8 arithmetic.

Useful for testing.

Template Parameters

GridVisitor

Parameters

start	start point
end	end point
visitor	called for each cell visited.

Fully tested.

Template Parameters

GridVisitor

Parameters

start	start point
end	end point
visitor	called for each cell visited.

Fully tested.

Definition at line 67 of file traverse_grid.h.

                                                           {
    int x0 = static_cast<int>(fl::floor(start.x));
    int y0 = static_cast<int>(fl::floor(start.y));
    int x1 = static_cast<int>(fl::floor(end.x));
    int y1 = static_cast<int>(fl::floor(end.y));
 
    int stepX = (x1 > x0) ? 1 : (x1 < x0) ? -1 : 0;
    int stepY = (y1 > y0) ? 1 : (y1 < y0) ? -1 : 0;
 
    float dx = end.x - start.x;
    float dy = end.y - start.y;
 
    float tDeltaX = (dx != 0.0f) ? ABS(1.0f / dx) : FLT_MAX;
    float tDeltaY = (dy != 0.0f) ? ABS(1.0f / dy) : FLT_MAX;
 
    float nextX = (stepX > 0) ? (fl::floor(start.x) + 1) : fl::floor(start.x);
    float nextY = (stepY > 0) ? (fl::floor(start.y) + 1) : fl::floor(start.y);
 
    float tMaxX = (dx != 0.0f) ? ABS((nextX - start.x) / dx) : FLT_MAX;
    float tMaxY = (dy != 0.0f) ? ABS((nextY - start.y) / dy) : FLT_MAX;
 
    float maxT = 1.0f;
 
    int currentX = x0;
    int currentY = y0;
 
    while (true) {
        visitor.visit(currentX, currentY);
        float t = MIN(tMaxX, tMaxY);
        if (t > maxT)
            break;
 
        if (tMaxX < tMaxY) {
            tMaxX += tDeltaX;
            currentX += stepX;
        } else {
            tMaxY += tDeltaY;
            currentY += stepY;
        }
    }
 
    // Ensure the end cell (x1, y1) is visited at least once
    if (currentX != x1 || currentY != y1) {
        visitor.visit(x1, y1);
    }
}

References ABS, floor(), FLT_MAX, MIN, fl::vec2< T >::x, and fl::vec2< T >::y.

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