Further upgrading put pixel.

[cameron]

Is there anyway to further optimise put pixell after intermediate lesson 6?

[NaturalDemon]

yes, there is ... but not performance wise ... it´s bare ...
but ... i added a line .. for pixels that fall outside of the window client rect ...
but i can´t post it right now, i don´t have the laptop ...

[Zionich]

I did also. It looked like

if (x >= 0 && x <= screenwidth && y >= 0 && y <= screenheight)
{
PutPixel (.........);
}



This allowed me to pull things off screen into the screen a little at a time.

[Musi]

Although you should test to see if the object you're drawing is moving off the screen before you use that. Using an if statement on every pixel all the time will slow your program.

[cameron]

I'm mainly looking for a further performance boost.

[NaturalDemon]

well, tell me how?

any test .. would add further if statements

Code: Select all

if (x >= 0 && x <= screenwidth && y >= 0 && y <= screenheight)
{
PutPixel (.........);
}

mine looks like this

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// screenwidthv & screenheigh are defined in windows.cpp and passed by reference
if ( ( x >= 0 & x <= &screenwidth ) && ( y >= 0 & y <= &screenheigh ) )
{
PutPixel (.........);
}

[Musi]

For example, if you're drawing a sprite thats 20x20. Test it's coordinates to see if any part of it is outside the screen. Assuming the the coordinates are at the top left of the sprite, something like:

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void DrawSprite( int x, int y )
{
        if( x < 0 || x + 20 > SCREENWIDTH ||
            y < 0 || y + 20 > SCREENHEIGHT )
         {
               DrawSpriteClipped( x,y );
         }
        else
         {
               DrawSprite( x,y );
         }
}

The DrawSpriteClipped function would use the PutPixel with the if statement, the normal DrawSprite function would use the normal PutPixel. This way if the sprite is fully on the screen, you only use one if statement, instead of 400.

[NaturalDemon]

I'm mainly looking for a further performance boost.

i think i know what you mean.
the loops that use putpixel .... only handle rectangles.

i was thinking about adding dynamic D3DCOLOR buffers to store reuseble "images" and copy them directly

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void D3DGraphics::PutPixel( int x,int y,int r,int g,int b )
{	
	assert( x >= 0 );
	assert( y >= 0 );
	assert( x < SCREENWIDTH );
	assert( y < SCREENHEIGHT );
	pSysBuffer[ x + SCREENWIDTH * y ] = D3DCOLOR_XRGB( r,g,b );
}

void D3DGraphics::PutPixel( int x,int y,D3DCOLOR c )
{	
	assert( x >= 0 );
	assert( y >= 0 );
	assert( x < SCREENWIDTH );
	assert( y < SCREENHEIGHT );
	pSysBuffer[ x + SCREENWIDTH * y ] = c;
}

on the other hand ... this equation

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x + SCREENWIDTH * y 

can be removed from the put pixel method.
x + SCREENWIDTH * y in realty is a fixed value during the session and could be declared somewhere else and would save atleast 2 cpu cycles each time put pixel gets called.


all this ...

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	assert( x >= 0 );
	assert( y >= 0 );
	assert( x < SCREENWIDTH );
	assert( y < SCREENHEIGHT );

can be removed if you use Zionich solution, it's meaningsless after you test if the x,y are inside the cleint rect and would save atleast another 8 cpu cycles.
so in total you can speed up and save some 10 cpu cycles .. but lose about 4 on the test ..

[NaturalDemon]

For example, if you're drawing a sprite thats 20x20. Tests it's coordinates to see if any part of it is outside the screen. Assuming the the coordinates are at the top left of the sprite, something like:

Code: Select all

void DrawSprite( int x, int y )
{
        if( x < 0 || x + 20 > SCREENWIDTH ||
            y < 0 || y + 20 > SCREENHEIGHT )
         {
               DrawSpriteClipped( x,y );
         }
        else
         {
               DrawSprite( x,y );
         }
}

The DrawSpriteClipped function would use the PutPixel with the if statement, the normal DrawSprite function would use the normal PutPixel. This way if the sprite is fully on the screen, you only use one if statement, instead of 400.

you're wrong ... sorry to say
(see image) http://www.planetchili.net/forum/viewto ... e&start=10

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( x < 0 || x + 20 > SCREENWIDTH || y < 0 || y + 20 > SCREENHEIGHT )

is much slower than

Code: Select all

i(x >= 0 && x <= screenwidth && y >= 0 && y <= screenheight)

[cameron]

A test will only make the game slow down. I want a performance boost to make the game run faster.