Re: Fast graphics in C# - C# Discussion Boards

25-Aug-03 20:37

I'm trying to write a game in C# to learn the language.
It's a mini clone of civilization III.
The main game window is a map, drawn with tiles (20x20 tiles right now).
To draw the map, I have somewhere a Bitmap that I store as backbuffer, where I draw the tiles themselves. Then to animate the sprites I use this "map bitmap", and draw the sprites above it.
To draw a tile, I have canvas in memory, with all the braw bitmaps (they contains 9x9 tiles), I select the right tile (-> creation of a source rectangle, corresponding to the right tile in the canvas), then I draw it in my Bitmap, after having found the destination rectangle.

So basically it's something like

graphics.Draw(CanvasBitmap, SourceRectangle, DestinationRectangle).

I have some problem with speed : rendering 20x20 tiles (each is 128x64) takes 950 ms. As I need to render it anytime I scroll (because the map is 200x200, but the viewport is only 20x20), it is not acceptable.

Is there a way to speed the process using only GDI+ and C#?

Must I use direct X?

Meysam Mahfouzi25-Aug-03 23:35

Meysam Mahfouzi

25-Aug-03 23:35

Try this approach:
Choose the graphics surface of a PictureBox control instead of drawing on a Bitmap object, I mean do your drawing in OnPaint event of PictureBox control(and use e.Graphics). This way you can use benefits of auto scrolling that PictureBox control has. And also speed is more acceptable than when you draw on a Bitmap object.
I hope this helps

Don't forget, that's

Persian Gulf

not Arabian gulf!

Stephane David26-Aug-03 1:26

26-Aug-03 1:26

I can' do this, because I want to precalculate the map backgrounds only when the user wants to scroll. Then moving sprites on the map doesn't need any change in the map itself, so I will use the precalculated bitmap.

Ista26-Aug-03 4:46

Ista

26-Aug-03 4:46

Meisi wrote:
This way you can use benefits of auto scrolling that PictureBox control has. And also speed is more acceptable than when you draw on a Bitmap object.

For a business app maybe.

BitBltFast would actually be the wiseest choice. picture boxes are slow.

I only say this because I'm writing a game in c# right now and have discovered the the GDI+ sucks

I'm not an expert yet, but I play one at work. Yeah and here too.

Philip Fitzsimons26-Aug-03 2:28

26-Aug-03 2:28

something not right here.
- are you drawing all 400 tiles each time?
- are you moving them onscreen in one move or 400 moves?

"When the only tool you have is a hammer, a sore thumb you will have."

Stephane David26-Aug-03 3:55

26-Aug-03 3:55

I draw all the 400 tiles each times, because if the user clicks on the globalview "somewhere", I need to redraw all of it.
However, I do it only when the map change (scroll or editor change of terrain), no when things in the layers (a unit animation change).
I move them on screen in one move : I start by drawing them in a bitmap, which is stored, and then in the render function (with a timer), I draw the stored bitmap in the PictureBox.

This last part is fast. I don't understand why drawing the 400 128x64 tiles in the backbuffer is so much longer than drawing the whole image in a 1024x768 PictureBox?

Philip Fitzsimons26-Aug-03 4:25

26-Aug-03 4:25

becuase its 400 times more work....

you need less calls

"When the only tool you have is a hammer, a sore thumb you will have."

Philip Fitzsimons26-Aug-03 4:43

26-Aug-03 4:43

you should cache your whole "world".
i.e. make your buffer as big as the world, and only redraw those in the 400 that have changed.

this way you should only have to do a few redraws..

"When the only tool you have is a hammer, a sore thumb you will have."

Stephane David26-Aug-03 5:06

26-Aug-03 5:06

World = 200x200 tiles.
Tile = 128x64 pixels.
As they overlap (isometric view),
let say it's 100x100 tiles.

That's still 81 920 000 pixels... Isn't it to much to store the whole background?

Philip Fitzsimons26-Aug-03 5:46

26-Aug-03 5:46

yes that is pretty big...

maybe you need to reconsider how you draw your world - maybe tiles are not a good idea...

"When the only tool you have is a hammer, a sore thumb you will have."

Stephane David26-Aug-03 11:04

26-Aug-03 11:04

Before I did this

graphics.DrawImage(backgroundSprite.Canvas.PictureFile,destinationRectangle,backgroundSprite.SourceRect,GraphicsUnit.Pixel);

and I had in memory one file with 9x9 tiles. I selected the tile from the source rectangle, and copied it in my PictureBox.

Now I have that :

graphics.DrawImage(backgroundCanvasArray[BackgroundCanvas].TilesArray[line,column],offsetX,offsetY);

and I have an array of tile 9x9.

Initialization is a bit longer, as I have to break my 9x9 tiles images into 81 images in an array.

But then, for the rendering I simply draw the tiles directly at the offset, without specifying a source and destination rectangle.

Result : rendering time for a 20x20 tiles world has dropped from 950 ms to 30 ms.

What took time was the resampling of the image to fit the new size, EVEN IF IT WAS THE SAME SIZE.

Now it works well enough

Philip Fitzsimons26-Aug-03 23:11

26-Aug-03 23:11

glad to here you fixed it!

"When the only tool you have is a hammer, a sore thumb you will have."

Ista26-Aug-03 4:45

Ista

26-Aug-03 4:45

Well your first and biggest mistake is not using direct x as a window in your application. GDI sucks for that type of application

Second you need to redraw based on regions.

My advice:

get rid of gdi+ dont even bother with it.

learn direct x and set up the buffered pages

one for the map, cities, and the objects then flip the pages and you ll get plenty of speed

nick

I'm not an expert yet, but I play one at work. Yeah and here too.