agg_scanline_boolean_algebra.h

来自「这是VCF框架的代码」· C头文件 代码 · 共 1,568 行 · 第 1/4 页

        ren.prepare();

        // The main loop
        // Here we synchronize the scanlines with 
        // the same Y coordinate, ignoring all other ones.
        // Only scanlines having the same Y-coordinate 
        // are to be combined.
        //-----------------
        for(;;)
        {
            while(sl1.y() < sl2.y())
            {
                if(!sg1.sweep_scanline(sl1)) return;
            }
            while(sl2.y() < sl1.y())
            {
                if(!sg2.sweep_scanline(sl2)) return;
            }

            if(sl1.y() == sl2.y())
            {
                // The Y coordinates are the same.
                // Combine the scanlines, render if they contain any spans,
                // and advance both generators to the next scanlines
                //----------------------
                sbool_intersect_scanlines(sl1, sl2, sl, combine_spans);
                if(sl.num_spans())
                {
                    sl.finalize(sl1.y());
                    ren.render(sl);
                }
                if(!sg1.sweep_scanline(sl1)) return;
                if(!sg2.sweep_scanline(sl2)) return;
            }
        }
    }







    //-------------------------------------------------sbool_unite_scanlines
    // Unite two scanlines, "sl1" and "sl2" and generate a new "sl" one.
    // The combine_spans functor can be of type sbool_combine_spans_bin or
    // sbool_intersect_spans_aa. First is a general functor to combine
    // two spans without Anti-Aliasing, the second preserves the AA
    // information, but works slower
    //
    template<class Scanline1, 
             class Scanline2, 
             class Scanline, 
             class AddSpanFunctor1,
             class AddSpanFunctor2,
             class CombineSpansFunctor>
    void sbool_unite_scanlines(const Scanline1& sl1, 
                               const Scanline2& sl2, 
                               Scanline& sl, 
                               AddSpanFunctor1 add_span1,
                               AddSpanFunctor2 add_span2,
                               CombineSpansFunctor combine_spans)
    {
        sl.reset_spans();

        unsigned num1 = sl1.num_spans();
        unsigned num2 = sl2.num_spans();

        typename Scanline1::const_iterator span1;// = sl1.begin();
        typename Scanline2::const_iterator span2;// = sl2.begin();

        enum invalidation_e 
        { 
            invalid_b = 0xFFFFFFF, 
            invalid_e = invalid_b - 1 
        };

        // Initialize the spans as invalid
        //---------------
        int xb1 = invalid_b;
        int xb2 = invalid_b;
        int xe1 = invalid_e;
        int xe2 = invalid_e;

        // Initialize span1 if there are spans
        //---------------
        if(num1)
        {
            span1 = sl1.begin();
            xb1 = span1->x;
            xe1 = xb1 + abs((int)span1->len) - 1;
            --num1;
        }

        // Initialize span2 if there are spans
        //---------------
        if(num2)
        {
            span2 = sl2.begin();
            xb2 = span2->x;
            xe2 = xb2 + abs((int)span2->len) - 1;
            --num2;
        }


        for(;;)
        {
            // Retrieve a new span1 if it's invalid
            //----------------
            if(num1 && xb1 > xe1) 
            {
                --num1;
                ++span1;
                xb1 = span1->x;
                xe1 = xb1 + abs((int)span1->len) - 1;
            }

            // Retrieve a new span2 if it's invalid
            //----------------
            if(num2 && xb2 > xe2) 
            {
                --num2;
                ++span2;
                xb2 = span2->x;
                xe2 = xb2 + abs((int)span2->len) - 1;
            }

            if(xb1 > xe1 && xb2 > xe2) break;

            // Calculate the intersection
            //----------------
            int xb = xb1;
            int xe = xe1;
            if(xb < xb2) xb = xb2;
            if(xe > xe2) xe = xe2;
            int len = xe - xb + 1; // The length of the intersection
            if(len > 0)
            {
                // The spans intersect,
                // add the beginning of the span
                //----------------
                if(xb1 < xb2)
                {
                    add_span1(span1, xb1, xb2 - xb1, sl);
                    xb1 = xb2;
                }
                else
                if(xb2 < xb1)
                {
                    add_span2(span2, xb2, xb1 - xb2, sl);
                    xb2 = xb1;
                }

                // Add the combination part of the spans
                //----------------
                combine_spans(span1, span2, xb, len, sl);


                // Invalidate the fully processed span or both
                //----------------
                if(xe1 < xe2)
                {
                    // Invalidate span1 and eat
                    // the processed part of span2
                    //--------------
                    xb1 = invalid_b;    
                    xe1 = invalid_e;
                    xb2 += len;
                }
                else
                if(xe2 < xe1)
                {
                    // Invalidate span2 and eat
                    // the processed part of span1
                    //--------------
                    xb2 = invalid_b;  
                    xe2 = invalid_e;
                    xb1 += len;
                }
                else
                {
                    xb1 = invalid_b;  // Invalidate both
                    xb2 = invalid_b;
                    xe1 = invalid_e;
                    xe2 = invalid_e;
                }
            }
            else
            {
                // The spans do not intersect
                //--------------
                if(xb1 < xb2) 
                {
                    // Advance span1
                    //---------------
                    if(xb1 <= xe1)
                    {
                        add_span1(span1, xb1, xe1 - xb1 + 1, sl);
                    }
                    xb1 = invalid_b; // Invalidate
                    xe1 = invalid_e;
                }
                else
                {
                    // Advance span2
                    //---------------
                    if(xb2 <= xe2)
                    {
                        add_span2(span2, xb2, xe2 - xb2 + 1, sl);
                    }
                    xb2 = invalid_b; // Invalidate
                    xe2 = invalid_e;
                }
            }
        }
    }




    //----------------------------------------------------sbool_unite_shapes
    // Unite the scanline shapes. Here the "Scanline Generator" 
    // abstraction is used. ScanlineGen1 and ScanlineGen2 are 
    // the generators, and can be of type rasterizer_scanline_aa<>.
    // There function requires three scanline containers that can be 
    // of different type.
    // "sl1" and "sl2" are used to retrieve scanlines from the generators,
    // "sl" is ised as the resulting scanline to render it.
    // The external "sl1" and "sl2" are used only for the sake of
    // optimization and reusing of the scanline objects.
    // the function calls sbool_unite_scanlines with CombineSpansFunctor 
    // as the last argument. See sbool_unite_scanlines for details.
    //----------
    template<class ScanlineGen1, 
             class ScanlineGen2, 
             class Scanline1, 
             class Scanline2, 
             class Scanline, 
             class Renderer,
             class AddSpanFunctor1,
             class AddSpanFunctor2,
             class CombineSpansFunctor>
    void sbool_unite_shapes(ScanlineGen1& sg1, ScanlineGen2& sg2,
                            Scanline1& sl1, Scanline2& sl2,
                            Scanline& sl, Renderer& ren, 
                            AddSpanFunctor1 add_span1,
                            AddSpanFunctor2 add_span2,
                            CombineSpansFunctor combine_spans)
    {
        // Prepare the scanline generators.
        // If anyone of them doesn't contain 
        // any scanlines, then return.
        //-----------------
        bool flag1 = sg1.rewind_scanlines();
        bool flag2 = sg2.rewind_scanlines();
        if(!flag1 && !flag2) return;

        // Get the bounding boxes
        //----------------
        rect_i r1(sg1.min_x(), sg1.min_y(), sg1.max_x(), sg1.max_y());
        rect_i r2(sg2.min_x(), sg2.min_y(), sg2.max_x(), sg2.max_y());

        // Calculate the union of the bounding boxes
        //-----------------
        rect_i ur(1,1,0,0);
             if(flag1 && flag2) ur = unite_rectangles(r1, r2);
        else if(flag1)          ur = r1;
        else if(flag2)          ur = r2;

        if(!ur.is_valid()) return;

        ren.prepare();

        // Reset the scanlines and get two first ones
        //-----------------
        sl.reset(ur.x1, ur.x2);
        if(flag1) 
        {
            sl1.reset(sg1.min_x(), sg1.max_x());
            flag1 = sg1.sweep_scanline(sl1);
        }

        if(flag2) 
        {
            sl2.reset(sg2.min_x(), sg2.max_x());
            flag2 = sg2.sweep_scanline(sl2);
        }

        // The main loop
        // Here we synchronize the scanlines with 
        // the same Y coordinate.
        //-----------------
        while(flag1 || flag2)
        {
            if(flag1 && flag2)
            {
                if(sl1.y() == sl2.y())
                {
                    // The Y coordinates are the same.
                    // Combine the scanlines, render if they contain any spans,
                    // and advance both generators to the next scanlines
                    //----------------------
                    sbool_unite_scanlines(sl1, sl2, sl, 
                                          add_span1, add_span2, combine_spans);
                    if(sl.num_spans())
                    {
                        sl.finalize(sl1.y());
                        ren.render(sl);
                    }
                    flag1 = sg1.sweep_scanline(sl1);
                    flag2 = sg2.sweep_scanline(sl2);
                }
                else
                {
                    if(sl1.y() < sl2.y())
                    {
                        sbool_add_spans_and_render(sl1, sl, ren, add_span1);
                        flag1 = sg1.sweep_scanline(sl1);
                    }
                    else
                    {
                        sbool_add_spans_and_render(sl2, sl, ren, add_span2);
                        flag2 = sg2.sweep_scanline(sl2);
                    }
                }
            }
            else
            {
                if(flag1)
                {
                    sbool_add_spans_and_render(sl1, sl, ren, add_span1);
                    flag1 = sg1.sweep_scanline(sl1);
                }
                if(flag2)
                {
                    sbool_add_spans_and_render(sl2, sl, ren, add_span2);
                    flag2 = sg2.sweep_scanline(sl2);
                }
            }
        }
    }








    //-------------------------------------------------sbool_subtract_shapes
    // Subtract the scanline shapes, "sg1-sg2". Here the "Scanline Generator" 
    // abstraction is used. ScanlineGen1 and ScanlineGen2 are 
    // the generators, and can be of type rasterizer_scanline_aa<>.
    // There function requires three scanline containers that can be of
    // different types.
    // "sl1" and "sl2" are used to retrieve scanlines from the generators,
    // "sl" is ised as the resulting scanline to render it.
    // The external "sl1" and "sl2" are used only for the sake of
    // optimization and reusing of the scanline objects.
    // the function calls sbool_intersect_scanlines with CombineSpansFunctor 
    // as the last argument. See combine_scanlines_sub for details.
    //----------
    template<class ScanlineGen1, 
             class ScanlineGen2, 
             class Scanline1, 
             class Scanline2, 
             class Scanline, 
             class Renderer,
             class AddSpanFunctor1,
             class CombineSpansFunctor>
    void sbool_subtract_shapes(ScanlineGen1& sg1, ScanlineGen2& sg2,
                               Scanline1& sl1, Scanline2& sl2,
                               Scanline& sl, Renderer& ren, 
                               AddSpanFunctor1 add_span1,
                               CombineSpansFunctor combine_spans)
    {
        // Prepare the scanline generators.
        // Here "sg1" is master, "sg2" is slave.
        //-----------------
        if(!sg1.rewind_scanlines()) return;
        bool flag2 = sg2.rewind_scanlines();

        // Get the bounding box
        //----------------
        rect_i r1(sg1.min_x(), sg1.min_y(), sg1.max_x(), sg1.max_y());

        // Reset the scanlines and get two first ones
        //-----------------
        sl.reset(sg1.min_x(), sg1.max_x());
        sl1.reset(sg1.min_x(), sg1.max_x());
        sl2.reset(sg2.min_x(), sg2.max_x());
        if(!sg1.sweep_scanline(sl1)) return;