graphics - Java 2D Rendering Ripple Artifacts -

i'm working on isometric 2d game in java , noticed there grid of lines on screen rendering seems repeat pixel horizontally , vertically. here's screenshot show mean:

i checked loop in render method , compared each pixel's color value previous value in array see if there occurrence of 2 black pixels in row , no such occurrence found. i'm @ loss causing effect. can fix this? here's relevant code:

game class variables:

private bufferedimage m_imgimage = new bufferedimage( intcanvas_width, intcanvas_height, bufferedimage.type_int_rgb ); private int[ ] m_aintpixels = ( ( databufferint ) m_imgimage.getraster( ).getdatabuffer( ) ).getdata( ); 

game class render method:

// object organize data on canvas bufferstrategy bfsbufferstrategy = getbufferstrategy( );  if( bfsbufferstrategy == null ) {     createbufferstrategy( 3 );     return; }  for( int inty = 0; inty < intcanvas_height; inty += 1 ) {     for( int intx = 0; intx < intcanvas_width; intx += 1 )     {         m_aintpixels[ intx + ( inty * intcanvas_width ) ] = m_screen.m_aintpixels[ intx + ( inty * m_screen.m_intwidth ) ];     } }  graphics gfxgraphics = bfsbufferstrategy.getdrawgraphics( ); gfxgraphics.drawimage( m_imgimage, 0, 0, getwidth( ), getheight( ), null );   gfxgraphics.dispose( ); bfsbufferstrategy.show( ); 

screen class render method populate pixel array:

// render tile specified tile id public void rendertile( int intpositionx, int intpositiony, cspritesheet spritesheet, int inttileid ) {      int intpixelindex = 0;     int intsheetx = 0;     int intsheety = 0;     int inttileoffsetx = 0;     int inttileoffsety = 0;     int intpixelcolor = 0;      // center tile     intpositionx -= m_intoffsetx;     intpositiony -= m_intoffsety;      intsheetx = ( inttileid % spritesheet.m_inttilecolumns ) * ctile.tile_width;     intsheety = ( inttileid / spritesheet.m_inttilerows ) * ctile.tile_height;      intpixelindex = intpositionx + ( intpositiony * m_intwidth );      // rows     for( int inttilerow = intsheety; inttilerow != ( intsheety + ctile.tile_height ); inttilerow += 1 )     {         // columns         for( int inttilecolumn = intsheetx; inttilecolumn != ( intsheetx + ctile.tile_width ); inttilecolumn += 1 )         {             intpixelcolor = spritesheet.m_aintpixels[ inttilecolumn + ( inttilerow * m_spritesheet.m_intwidth ) ];              // boundary checking             if( intpositionx + inttileoffsetx >= 0 && intpositionx + inttileoffsetx < m_intwidth &&             intpositiony + inttileoffsety >= 0 && intpositiony + inttileoffsety < m_intheight &&             ccolor.transparent( intpixelcolor ) == false )             {                  m_aintpixels[ intpixelindex ] = spritesheet.m_aintpixels[ inttilecolumn + ( inttilerow * m_spritesheet.m_intwidth ) ];             }              // increment             inttileoffsetx += 1;             intpixelindex += 1;         }          // increment         inttileoffsety += 1;         intpixelindex += m_intwidth - ( ctile.tile_width );         inttileoffsetx = 0;     } } 

this classic artifact of non-interpolated scaling. have:

private bufferedimage m_imgimage = new bufferedimage( intcanvas_width, intcanvas_height, bufferedimage.type_int_rgb ); ... gfxgraphics.drawimage( m_imgimage, 0, 0, getwidth( ), getheight( ), null ); 

the effect seeing because getwidth() , getheight() larger intcanvas_width , intcanvas_height. when draw graphic, scales larger. it's not using kind of interpolation scaling, picking nearest pixel source; therefore see duplicate rows or columns @ regular intervals.

you not see when check source data because not present in source data, it's artifact introduced in output when data rendered.

print out image , panel dimensions , see difference. judging count of duplicate rows see (i see 10 horizontal , 10 vertical), guess find getwidth() 10 more intcanvas_width, , same height.

you pass dimensions of m_imgimage .drawimage() instead. rid of artifact leave gap on right , bottom since image smaller component.

if graphics graphics2d, can set key_interpolation rendering hint use interpolation when scaling (it may not obey hint):

graphics2d g = (graphics2d)gfxgraphics; g.setrenderinghint(renderinghints.key_interpolation, renderinghints.value_interpolation_bilinear); 

if want image drawn exactly, without scaling, , without gap on sides, disable resizing on main window , set size match image.