void set_psetp_mode(n)
By default, you can't set the alpha channel to zero with psetp. This is an intended behavior, that allows to use psetp function in conjuction with RGB function without messing up alpha channel ( i.e psetp(x,y,RGB(r,g,b)) ). To cancel this behavior, just do the instruction set_psetp_mode(1).
%ffp SupportedModes:RGBMode // The default color is orange, // but you can change it with // sliders ctl[0]: "R value", Range=(0,255), Val=255 ctl[1]: "G value", Range=(0,255), Val=128 ctl[2]: "B value", Range=(0,255), Val=0 ForEveryTile: { int color; // Check if alpha channel available if ( Z<4 ) { Info("This plug-in needs to " "be applied to a layer to " "achieve the effect"); return true; } //------- the important line set_psetp_mode(1); for( y=y_start; y<y_end; y++) { for(x=x_start; x<x_end; x++) { // Chess board pattern if( ((x%100)<50) ^ ((y%100)<50) ) { a=255; } else { a=0; } color = RGBA(ctl(0), ctl(1), ctl(2), a); psetp(x,y,color); } // end for x } // end for y return true; } // end ForEveryTile
Everyone can add his comments about his experiences with this function here. Tips for using it are welcome, too.