Drawn images using ImageBuffer do not show

Hello

I am writing a program that Draws and Image in an Imagebuffer (using createImage and Plot) and then Tiles the image across the screen. However, the Tile does not work until after I have run the program, clicked another window, and clicked back on to the program. This seems to be an event error, but I don't know how to correct it.

Following is the code.

;INITIALIZATION

;Set up the graphics
Graphics 800,600,0,2



;Seed the Random Generator
SeedRnd MilliSecs()

;CONSTANTS
;The length of each block
Const LENGTH = 100

;The height of each block
Const HEIGHT = 100

;The amount of dots in each block
Const DOTS = 100
;END CONSTANTS



;IMAGES
;Create the dotfield image
dotfieldimage = CreateImage(LENGTH,HEIGHT)
;END IMAGES

;For each dot, draw a random dot at a random location
For loop = 0 To DOTS ;For every star
;draw only on created image
SetBuffer ImageBuffer(dotfieldimage)

;Plot the dot
Plot Rnd(LENGTH), Rnd(HEIGHT)

Next

;Set buffer back to normal
SetBuffer FrontBuffer()
;END INITIALIZATION

;MAIN LOOP

;Tile the image until the user quits (presses ESC)
While Not KeyDown(1)
TileImage dotfieldimage
Wend

;END MAIN LOOP



Thank you

-Maneesh

must be an error in your computer, works fine for me

The error is more obvious (happens 100% of the time) if you change the Graphics code to

Graphics 800,600

So the code becomes:


;INITIALIZATION

;Set up the graphics
Graphics 800,600



;Seed the Random Generator
SeedRnd MilliSecs()

;CONSTANTS
;The length of each block
Const LENGTH = 100

;The height of each block
Const HEIGHT = 100

;The amount of dots in each block
Const DOTS = 100
;END CONSTANTS



;IMAGES
;Create the dotfield image
dotfieldimage = CreateImage(LENGTH,HEIGHT)
;END IMAGES

;For each dot, draw a random dot at a random location
For loop = 0 To DOTS ;For every star
;draw only on created image
SetBuffer ImageBuffer(dotfieldimage)

;Plot the dot
Plot Rnd(LENGTH), Rnd(HEIGHT)

Next

;Set buffer back to normal
SetBuffer FrontBuffer()
;END INITIALIZATION

;MAIN LOOP

;Tile the image until the user quits (presses ESC)
While Not KeyDown(1)
TileImage dotfieldimage
Wend

;END MAIN LOOP


Thanks

-Maneesh

The code above tiles the screen with an image. I think his may have something to do with drawing buffers. And i also assume your using blitzplus? If so, it uses the backbuffer for drawing by default.

Put in:

Flip

After your Wend.

Try to always use the backbuffer for drawing, then flip before the wend in the main loop. :o)

When I put in Flip, it works when not in fullscreen mode. However, in full screen mode, it doesn't work. I get a blank beige screen. What is going on?

Thanks

-Maneesh

YOu need to get rid of your setbuffer frontbuffer command. Forgot to mention that ^_^

When I set it to use the backbuffer, and use Flip, the screen alternates between blank beige and the star images. I still don't know what is happening.

Ok, here's my code :

I changed the SetBuffer FrontBuffer() command to SetBuffer BackBuffer(). And added flip.

;Set up the graphics 
Graphics 800,600 



;Seed the Random Generator 
SeedRnd MilliSecs() 

;CONSTANTS 
;The length of each block 
Const LENGTH = 100 

;The height of each block 
Const HEIGHT = 100 

;The amount of dots in each block 
Const DOTS = 100 
;END CONSTANTS 



;IMAGES 
;Create the dotfield image 
dotfieldimage = CreateImage(LENGTH,HEIGHT) 
;END IMAGES 

;For each dot, draw a random dot at a random location 
For loop = 0 To DOTS ;For every star 
;draw only on created image 
SetBuffer ImageBuffer(dotfieldimage) 

;Plot the dot 
Plot Rnd(LENGTH), Rnd(HEIGHT) 

Next 

;Set buffer back to normal 
SetBuffer BackBuffer()
;END INITIALIZATION 

;MAIN LOOP 

;Tile the image until the user quits (presses ESC) 
While Not KeyDown(1) 
TileImage dotfieldimage
Flip
Wend 

;END MAIN LOOP

Awesome thanks! The only thing is, when I run your program, it flips very rapidly and you can very easily see a blank beige color being alternated at the same time as the star image. Do you know why?

Are you using the exact same code as mine?

yes, i copied and pasted it directly. Is it a problem with my computer?

This is blitzplus, by the way

I'm running this in blitzplus. Seems like an odd thing to happen. Have you set, or changed anything in your graphics card drivers?

Try: (added in a cls at the top of the main loop)

;Set up the graphics 
Graphics 800,600 



;Seed the Random Generator 
SeedRnd MilliSecs() 

;CONSTANTS 
;The length of each block 
Const LENGTH = 100 

;The height of each block 
Const HEIGHT = 100 

;The amount of dots in each block 
Const DOTS = 100 
;END CONSTANTS 



;IMAGES 
;Create the dotfield image 
dotfieldimage = CreateImage(LENGTH,HEIGHT) 
;END IMAGES 

;For each dot, draw a random dot at a random location 
For loop = 0 To DOTS ;For every star 
;draw only on created image 
SetBuffer ImageBuffer(dotfieldimage) 

;Plot the dot 
Plot Rnd(LENGTH), Rnd(HEIGHT) 

Next 

;Set buffer back to normal 
SetBuffer BackBuffer()
;END INITIALIZATION 

;MAIN LOOP 

;Tile the image until the user quits (presses ESC) 
While Not KeyDown(1)

cls
TileImage dotfieldimage
Flip
Wend 

;END MAIN LOOP

You say beige? That's an odd color to be changing too...

Perfect, that fixes it completely! Any idea why the Cls command would have any effect here?

Thanks

-Maneesh

Might be something to do with the tileimage command drawing over the previous contents of the buffer. I can't be sure :o) Usually put a cls in anyway, to wipe the buffer clean, before i draw.