C / C++ / MFC

/*-ScanlineLine2D-----------------------------------------------------------
 Scanline (sy) intersect and the line between the two vertices. The return
 will be 0 for no intersect or 1 and px will contain x intersect value.
 A horizontal line on the scan line will return no points as is consistant
 with scan lining.
 ---------------------------------------------------------------------------*/
short ScanlineLine2D(long x1, long y1,				// Vertex 1 (x1,y1)
					 long x2, long y2,				// Vertex 2 (x2,y2)
                     long sy, 		                // Scan line y value
                     long* px1){					// X interection pt
    long xt;
	double t;

	if (y2 == y1) return (0);										// Trivial fail horizontal line even if coincides with sy
	if (((sy >= y1) && (sy <= y2)) || ((sy >= y2) && (sy <= y1))){	// Check sy within range between y1 and y2
		
		// yt = (y2-y1)*t + y1		where 0 <= t <= 1, 
		// Re-arranging  t = (yt - y1)/(y2-y1)
		// Our yt value will be sy-epsilon so we don't get single corner points
		// t = ((sy-epsilon) - y1)/(y2-y1)
		// Re-arranging for floats   t = ((sy-y1)-epsilon)/(y2-y1)
		t = ((double)(sy-y1)-FLT_EPSILON)/(double)(y2-y1);		// Calculate t value

		if ( (t >= 0.0) && (t <= 1.0)) {				// Check valid 't'  0.0 <= t <= 1.0
			// xt = (x2-x1)*t + x1		where 0 <= t <= 1 
			xt = (long)((double)(x2-x1)*t) + x1;				// Calculate x at 't'
			if (px1) (*px1) = xt;											// Update intersect point x value
			return (1);												// We have 1 interesect point
		} else return (0);											// Invalid t value no intersection
	} else return (0);												// Return zero sy not in y1-y2 range
}


/*-ScanlineQuadBezier2D-----------------------------------------------------
 Scanline (sy) intersect and the quad bezier between the 3 control points.
 The return will be 0 for no intersect, 1 and px1 will contain x intersect 
 value or 2 and px1 and px2 will contain the x interect values.
 ---------------------------------------------------------------------------*/
short ScanlineQuadBezier2D(long x1, long y1,			// Vertex 1 (x1,y1) = On grid start pt
						   long x2, long y2,			// Vertex 2 (x2,y2) = Control Pt
						   long x3, long y3,			// Vertex 3 (x1,y1) = On grid End point
               			   long sy, 							// Scan line y value
                     	   long* px1, long* px2){		// Interection pt(s)

    short rslt;
	long dx0, dy0, dx1, dy1, dx2, dy2, xf;
	long* px;
    double tmf, tdf, tf, ymf;

	dx0 = x2 - x1;													// X diff between x2 and x1
	dy0 = y2 - y1;													// Y diff between y2 and y1
	dx1 = x3 - x2;													// X diff between x3 and x2
	dy1 = y3 - y2;													// Y diff between y3 and y2
	if ((dx0 == 0) && (dy0 == 0) && (dx1 == 0) && (dy1 == 0))		// All 3 points are one and same
		return (0);													// Drop point even if coincides with sy	
	if ((dx0 == 0) && (dy0 == 0))									// First 2 points are one and same
		return (ScanlineLine2D(x2, y2, x3, y3, sy, px1));			// Scanline as a line from (x2,y2)<->(x3,y3)
	if((dx1 == 0) && (dy1 == 0))									// Last two points are one and same	
		return (ScanlineLine2D(x1, y1, x2, y2, sy, px1));			// Scanline as a line from (x1,y1)<->(x2,y2)
	dx2 = (dx1-dx0);												// Difference between dx1 and dx0
	dy2 = (dy1-dy0);												// Differnece between dy1 and dy0
	if (dy2 != 0){													// y(t) = a*t*t + b*t + c
		// Calculate apex
		tmf = -(double)dy0/(double)dy2;								// 't' at apex point
		ymf = (double)y1 + FLT_EPSILON + tmf*(double)dy0;		// y at apex point
		tdf = ((double)sy - ymf)/(double)dy2;						// ''t' value at scanline
		if (tdf < 0.0) {									// If t value is invalid
			return (0);												// No intersect
		} else if (tdf != 0.0) tdf = sqrt(tdf);				// Take sqrt of t value
		rslt = 0;													// Preset intersect return count to zero
		px = px1;													// Preset intersect x ptr to px1
		tf = tmf - tdf;												// Calculate first test t value
		if ((tf >= 0.0) && (tf <= 1.0)){				// Valid 't'  0.0 <= t <= 1.0
			xf = (long)(((double)dx2*tf + (double)(dx0*2))*tf) + x1;// Calculate x point of intersec
			(*px) = xf;												// Transfer that result to *px
			rslt++;													// Increment intersect count
			px = px2;												// Advance point to px2
		};
		tf = tmf + tdf;												// Calculate second test t value
		if ((tf >= 0.0) && (tf <= 1.0)){				// Valid 't'  0.0 <= t <= 1.0
			xf = (long)(((double)dx2*tf + (double)(dx0*2))*tf) + x1;// Calculate x point of intersect
			(*px) = xf;												// Transfer that result to *px
			rslt++;													// Increment intersect count
			px = px2;												// Advance ptr to px2
		};		
		return (rslt);												// We can have one or two points returned
	} else if (dy0 != 0) {											// y(t) = b*t + c
		tf = ((double)(sy - y1) - FLT_EPSILON)/(double)(dy0*2);	// Calculate t of intersect
		if  ((tf >= 0.0) && (tf <= 1.0)){			// Valid 't'  0.0 <= t <= 1.0
			xf = (long)(((double)dx2*tf + (double)(dx0*2))*tf) + x1;// Calculate x point of intersect		
			(*px1) = xf;											// Transfer that result to px1
			return (1);												// Return 1 as intersect count
		} else return (0);											// Intersect is outside line segment
	} else return (0);												// Drop horizontal line even if coincides with sy
}

David Crow wrote:

Are the files that were in that folder on Monday still there on Tuesday?

In other words, are you processing every file in that folder, or just the new ones?

David Crow wrote:

So do the files that were processed on a Monday need to be processed again the next day?

jeron1 wrote:

If you comment out the 'Save buf in a std::vector' code, is it still unacceptably slow?

Member 3648633 wrote:

If I only do the search, without opening the file