Draw only a part of an image?
BlitzMax Forums/BlitzMax Programming/Draw only a part of an image?
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| Hi there! What would be a fast way to draw only a part of a larger image that is already loaded into memory (as Image Handle)? No Blending / Alpha required! Grisu |
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| Use LoadAnimImage:TImage( url:Object,cell_width,cell_height,first_cell,cell_count,flags=-1 ) to create tiles from the image then use drawimage to draw the section you want with the frame parameter. |
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| SetViewport looks like what you want. |
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| SetViewport is unreliable on some hardware. Try this (you'll have to use LockImage on myBigImage to use it as a pixmap). mySmallImage:tImage = LoadImage(PixmapWindow(myBigImage,x,y,width,height)) |
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| Thanks guys! |
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This should be faster. I use it for my games
' -----------------------------------------------------------------------------
' ccDrawImageArea: Draws part of an image.
' (by Ian Duff)
' -----------------------------------------------------------------------------
Function ccDrawImageArea(image:TImage, x#, y#, rx#, ry#, rw#, rh#, theframe%=0)
'Note that this code works fine in DirectX or OpenGL on PCs - it autodetects (Grey Alien).
'Warning: make sure that none of your images have pixels right on the edge otherwise
'when drawing clipped, they may leave smear in the clipped area! (Grey Alien).
Local origin_x#, origin_y# ; GetOrigin (origin_x, origin_y)
Local tw% = ccDrawImageAreaPow2Size(image.width)
Local th% = ccDrawImageAreaPow2Size(image.height)
Local rw1# = rx + rw
Local rh1# = ry + rh
Local x0# = -image.handle_x, x1# = x0 + rw
Local y0# = -image.handle_y, y1# = y0 + rh
If rw1 > image.width
x1 = x0 + rw + image.width - rw1
rw1 = image.width
EndIf
If rh1 > image.height
y1 = y0 + rh + image.height - rh1
rh1 = image.height
EndIf
?Win32
If TD3D7ImageFrame(image.frame(theframe))
Local frame:TD3D7ImageFrame = TD3D7ImageFrame(image.frame(theframe))
frame.setUV(rx / tw, ry / th, rw1 / tw, rh1 / th)
frame.Draw x0, y0, x1, y1, x + origin_x, y + origin_y
frame.setUV(0, 0, image.width / Float(tw), image.height / Float(th))
Else
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Local frameA:TGLImageFrame = TGLImageFrame (image.frame(theframe))
'Protect against frameA being null due to alt+tab. (Grey Alien)
If frameA<>Null Then
frameA.u0 = rx / tw
frameA.v0 = ry / th
frameA.u1 = rw1 / tw
frameA.v1 = rh1 / th
frameA.Draw x0, y0, x1, y1, x + origin_x, y + origin_y
frameA.u0 = 0
frameA.v0 = 0
frameA.u1 = image.width / Float(tw)
frameA.v1 = image.height / Float(th)
EndIf
?Win32
EndIf
?
Function ccDrawImageAreaPow2Size%(n%)
Local ry% = 1
While ry < n
ry :* 2
Wend
Return ry
End Function
End Function
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| "This should be faster." - Only on outdated gpu's. I didn't see a real "worth it" increase on newer gpu's. |
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I thought it was faster than this:mySmallImage:tImage = LoadImage(PixmapWindow(myBigImage,x,y,width,height))Because it worked directly in VRAM. |
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| ahh.. I see... ok. |
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| @ Grey Alien This looks pretty cool. I've been searching the forums for a while for a single surface blitting example that also included the conditional compilation as to avoid the "TD3D7ImageFrame indentifier not found" error (yeah, i could've written it myself...but thanks!) Would you say this workaround is on par with the TAnimImage class that Indiepath made? -Jason |
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| Looks like this function may have to be updated for the new TGLImageFrame.draw method parameters. |
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| Take a look at DrawSubImageRect which was added to Max2D in v1.36. |
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| Yup. I guess I'm just going to go with that. I'm not sure which is faster (Grey Alien approach, or DrawSubImageRect) but DrawSubImageRect is at least supported. |
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