BACKBUFFER ACCESS (MAX2d)
BlitzMax Forums/BlitzMax Programming/BACKBUFFER ACCESS (MAX2d)
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| Hi, I'm curious about how to access to the backbuffer in BlitzMax+Max2d before we call the FLIP command. I'm interested in implementig effect on the backbuffer drawings. Anyone has tryed yet? Any sample? Thx |
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| These functions are already in Bmax but are called something else - LOL and they are not very well documented. GrabPixmap - Grabs pixels directly from the backbuffer DrawPixmap - Draws pixeld directly to the backbuffer You can't draw a portion of an image to the buffer YET, but It would be simple to write a method to do that. |
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| Thx Indie, that's right what I was looking for. For filters programming I mostly need per-pixel manipulation. Thx again. |
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| No problem, now please someone help me with Vertex Buffers. |
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| Is it possible to get a pointer to the back buffer like in purebasic? |
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| Yes it is. |
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| Um. Ok, how? |
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| have a delve into the directx modules. If you have a look at the commands I mentioned earlier they are using a pointer to the back buffer to get and send information. |
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| Does it work with OpenGL? |
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| good question. I don't think you need it in openGl since you just need to read and write pixels, here's the BlitzMax Code : Method DrawPixmap( p:TPixmap,x,y ) Local blend=state_blend DisableTex SetBlend SOLIDBLEND Local t:TPixmap=YFlipPixmap(p) If t.format<>PF_RGBA8888 t=ConvertPixmap( t,PF_RGBA8888 ) glRasterPos2i 0,0 glBitmap 0,0,0,0,x,-y-t.height,Null glDrawPixels t.width,t.height,GL_RGBA,GL_UNSIGNED_BYTE,t.pixels SetBlend blend End Method Method GrabPixmap:TPixmap( x,y,w,h ) Local blend=state_blend SetBlend SOLIDBLEND Local p:TPixmap=CreatePixmap( w,h,PF_RGBA8888 ) glReadPixels x,graphics_height-h-y,w,h,GL_RGBA,GL_UNSIGNED_BYTE,p.pixels p=YFlipPixmap(p) SetBlend blend Return p End Method |
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| It is possible to add screen effect like blur or glow ? i have try but ... |
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| I suppose you could grab the backbuffer and apply that to a quad using the GRabImage function, then do some nice stuff with that image like creating some mipmapps and displaying those full screen - like a quick and dirty blur. I wonder if GrabImage keeps the stuff in video memory? that would be nice and quick if it did. |
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| How do you GrabImage/GrabPixMap if the image is drawn off screen? This would be helpful for a realtime grab without the need to Cls. |
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GrabPixMap grabs from the backbuffer. GrabIMages uses this function also but puts the pixmap that is returned by this function into a texture.Method GrabPixmap:TPixmap( x,y,width,height ) If islost Return Local pixmap:TPixmap pixmap=TPixmap.Create(width,height,PF_BGR888) Local sdesc:DDSurfaceDesc2=New DDSurfaceDesc2 sdesc.dwSize=SizeOf(sdesc) Local res=PrimaryDevice.backbuffer.Lock(Null,sdesc,DDLOCK_WAIT|DDLOCK_SURFACEMEMORYPTR|DDLOCK_READONLY,Null) If res<>DD_OK Return Select sdesc.ddpf_BitCount Case 16 Local s16:Short Ptr=Short Ptr(sdesc.lpSurface+y*sdesc.lPitch+x*2) Local d8:Byte Ptr=pixmap.pixels For Local i=0 Until height For Local j=0 Until width Local p=s16[j] d8[0]=p Shl 3 d8[1]=(p Shr 5) Shl 2 d8[2]=(p Shr 11) Shl 3 d8:+3 Next d8:+(pixmap.pitch-pixmap.width*3) s16:+sdesc.lPitch/2 Next Case 24 Local s8:Byte Ptr=sdesc.lpSurface+y*sdesc.lPitch+x*4 Local d8:Byte Ptr=pixmap.pixels For Local i=0 Until height memcpy_ d8,s8,pixmap.width*3 s8:+pixmap.pitch d8:+sdesc.lPitch Next Case 32 Local s8:Byte Ptr=sdesc.lpSurface+y*sdesc.lPitch+x*4 Local d8:Byte Ptr=pixmap.pixels For Local i=0 Until height For Local j=0 Until width d8[0]=s8[0] d8[1]=s8[1] d8[2]=s8[2] d8:+3 s8:+4 Next d8:+(pixmap.pitch-width*3) s8:+sdesc.lPitch-width*4 Next End Select PrimaryDevice.backbuffer.Unlock Null Return pixmap End Method End Type |
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