White quads instead of textured quads
Post: #1
Hi folks. This is my first post here.
I am using BlitzMax to create OpenGL programs. I am working on a program which should, simply, just load an image, upload it as a texture, then draw it to the display with texture mapping onto a quad.
On my humble G3 300Mhz ibook, which has software opengl only, the routine works fine and you see the textured quad on the screen.
However, I move to my G4 1GHz iMac,which has hardware accelerated opengl, and everything works except the texture disappears and is replaced with all white pixels.
Now, I read in another thread that this might be to do with the MIN and MAG filters not being set up when you aren't using mipmapping. I'm not using mipmapping so I have set up those both to GL_NEAREST. The problem still persists.
Is there some other thing that needs to be set or defined or something in order to make the texture show up?
Any insight or help greatly appreciated. You can see from the enclosed code the opengl calls mixed in with other BlitzMax commands, hopefully understandable. Note that comment lines or text begin with an apostrophe '''''''''
I am using BlitzMax to create OpenGL programs. I am working on a program which should, simply, just load an image, upload it as a texture, then draw it to the display with texture mapping onto a quad.
On my humble G3 300Mhz ibook, which has software opengl only, the routine works fine and you see the textured quad on the screen.
However, I move to my G4 1GHz iMac,which has hardware accelerated opengl, and everything works except the texture disappears and is replaced with all white pixels.
Now, I read in another thread that this might be to do with the MIN and MAG filters not being set up when you aren't using mipmapping. I'm not using mipmapping so I have set up those both to GL_NEAREST. The problem still persists.
Is there some other thing that needs to be set or defined or something in order to make the texture show up?
Any insight or help greatly appreciated. You can see from the enclosed code the opengl calls mixed in with other BlitzMax commands, hopefully understandable. Note that comment lines or text begin with an apostrophe '''''''''
Code:
Strict
Local ballsize:Int=256 'based on 256x256 image
Local ballsizehalf:Int=ballsize Shr 1
AutoMidHandle True
Local px1:TPixmap=LoadPixmap("Ball09.png") '4 to 9
px1=ConvertPixmap(px1,PF_RGBA8888)
bglCreateContext(640,480,32,0,BGL_BACKBUFFER|BGL_ALPHABUFFER|BGL_FULLSCREEN)'|BGL_STENCILBUFFER)
glViewport(0,0,640,480)
glMatrixMode (GL_PROJECTION)
glLoadIdentity
glOrtho(0,640,480,0,-1,1)
'gluOrtho2D(0,640,0,480)
glMatrixMode(GL_MODELVIEW)
glLoadIdentity
glClear(GL_COLOR_BUFFER_BIT)
bglSwapBuffers
glClear(GL_COLOR_BUFFER_BIT)
bglSwapBuffers
glDisable(GL_DEPTH_TEST)
glDisable(GL_STENCIL_TEST)
glDisable(GL_ALPHA_TEST)
glDisable(GL_SCISSOR_TEST)
glDisable(GL_CULL_FACE)
glDisable(GL_POLYGON_SMOOTH)
'glDisable(GL_LOGIC_OP)
glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_TRUE)
bglSetSwapInterval(0) 'no vbl sync
GLDisable(GL_DITHER)
glClearColor(0,0,0,0)
glColor4b($FF,$FF,$FF,$FF)
SeedRnd(MilliSecs())
'Create bank space to store a downloaded image
Local bnk:TBank=CreateBank(ballsize*ballsize) 'to store screen image
Local where:Byte Ptr=BankBuf(bnk)
'Give our image an alpha buffer
Local pxp:Byte Ptr=PixmapPixelPtr(px1,0,0)
Local pitch:Int=PixmapPitch(px1)
For Local yy:Int=0 To ballsize-1
Local yloc:Int=yy*pitch
For Local xx:Int=0 To ballsize-1
pxp[yloc+(xx Shl 2)+3]=pxp[yloc+(xx Shl 2)] 'copy the red component into the image's alpha buffer
Next
Next
'Pixmap now has equivalent data in alpha buffer
'Upload our pixmap as a texture
glDrawBuffer(GL_BACK)
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP_TO_EDGE)
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP_TO_EDGE)
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST)
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST)
glPixelStorei(GL_UNPACK_ALIGNMENT,4)
glPixelStorei(GL_UNPACK_ROW_LENGTH,PixmapPitch(px1)/4) '4 bytes per pixel RGB format
glPixelTransferf(GL_RED_SCALE,1.0)
glPixelTransferf(GL_RED_BIAS,0.0)
glPixelTransferf(GL_GREEN_SCALE,1.0)
glPixelTransferf(GL_GREEN_BIAS,0.0)
glPixelTransferf(GL_BLUE_SCALE,1.0)
glPixelTransferf(GL_BLUE_BIAS,0.0)
glPixelTransferf(GL_ALPHA_SCALE,1.0)
glPixelTransferf(GL_ALPHA_BIAS,0.0)
glPixelTransferi(GL_MAP_COLOR,GL_FALSE)
glPixelTransferi(GL_MAP_STENCIL,GL_FALSE)
glPixelStorei(GL_UNPACK_SWAP_BYTES,GL_FALSE)
glPixelStorei(GL_UNPACK_LSB_FIRST,GL_FALSE)
glPixelStorei(GL_UNPACK_SKIP_PIXELS,0)
glPixelStorei(GL_UNPACK_SKIP_ROWS,0)
Global name:Int=0
glGenTextures(1,VarPtr(name))
glBindTexture(GL_TEXTURE_2D,name)
glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,ballsize,ballsize,0,GL_RGBA,GL_UNSIGNED_BYTE,Null) 'RGB=no alpha in pixmap!
glPixelStorei(GL_UNPACK_ROW_LENGTH,PixmapPitch(px1)/4) '4 bytes per pixel RGB format
glTexSubImage2D GL_TEXTURE_2D,0,0,0,ballsize,ballsize,GL_RGBA,GL_UNSIGNED_BYTE,PixmapPixelPtr(px1,0,0)
Local objx:Int=Rand(0,619-ballsize)+10
Local objy:Int=Rand(0,459-ballsize)+10
Local objx2:Int=Rand(0,619-ballsize)+10
Local objy2:Int=Rand(0,459-ballsize)+10
Local xadd:Int=Rand(1,5)
Local yadd:Int=Rand(1,5)
Local xadd2:Int=Rand(1,5)
Local yadd2:Int=Rand(1,5)
Local spin:Int=0
Local spin2:Int=0
Repeat
'Move objects
If ballsize<620
objx:+xadd; objx2:+xadd2
If objx>630-ballsize Or objx<10
xadd=-xadd
objx:+xadd
EndIf
If objx2>630-ballsize Or objx2<10
xadd2=-xadd2
objx2:+xadd2
EndIf
EndIf
If ballsize<460
objy:+yadd; objy2:+yadd2
If objy>470-ballsize Or objy<10
yadd=-yadd
objy:+yadd
EndIf
If objy2>470-ballsize Or objy2<10
yadd2=-yadd2
objy2:+yadd2
EndIf
EndIf
glClear(GL_COLOR_BUFFER_BIT) 'cls
'SetBlend LIGHTBLEND
glEnable(GL_BLEND)
glBlendFunc GL_SRC_ALPHA,GL_ONE 'lightblend
'glBlendFunc GL_SRC_COLOR,GL_ONE_MINUS_SRC_COLOR
' glColorMask(GL_FALSE,GL_FALSE,GL_FALSE,GL_TRUE) 'Draw in alpha only
'spin=(spin+3) Mod 360
'SetRotation spin
'Draw texture
' glColor4b($FF,$FF,$FF,$80)
glEnable(GL_TEXTURE_2D)
glShadeModel(GL_FLAT)'SMOOTH)
glPolygonMode(GL_FRONT_AND_BACK,GL_FILL) 'face
glBegin GL_QUADS
' glTexCoord2f(0,0); glColor4b($FF,0,0,$80); glVertex2i(objx,objy)
' glTexCoord2f(0,1); glColor4b($FF,$FF,$FF,$80); glVertex2i(objx,objy+ballsize)
' glTexCoord2f(1,1); glColor4b($0,$0,$0,$80); glVertex2i(objx+ballsize,objy+ballsize)
' glTexCoord2f(1,0); glColor4b($FF,$FF,$FF,$80); glVertex2i(objx+ballsize,objy)
glTexCoord2f(0,0); glVertex2i(objx,objy)
glTexCoord2f(0,1); glVertex2i(objx,objy+ballsize)
glTexCoord2f(1,1); glVertex2i(objx+ballsize,objy+ballsize)
glTexCoord2f(1,0); glVertex2i(objx+ballsize,objy)
glEnd
'DrawImage img1,objx+ballsizehalf,objy+ballsizehalf
'SetRotation -spin
glBegin GL_QUADS
' glTexCoord2f(0,0); glColor4b(0,$FF,0,$80); glVertex2i(objx2,objy2)
' glTexCoord2f(0,1); glColor4b($FF,$FF,$FF,$80); glVertex2i(objx2,objy2+ballsize)
' glTexCoord2f(1,1); glColor4b($0,$0,$0,$80); glVertex2i(objx2+ballsize,objy2+ballsize)
' glTexCoord2f(1,0); glColor4b($FF,$FF,$FF,$80); glVertex2i(objx2+ballsize,objy2)
glTexCoord2f(0,0); glVertex2i(objx2,objy2)
glTexCoord2f(0,1); glVertex2i(objx2,objy2+ballsize)
glTexCoord2f(1,1); glVertex2i(objx2+ballsize,objy2+ballsize)
glTexCoord2f(1,0); glVertex2i(objx2+ballsize,objy2)
glEnd
'DrawImage img1,objx2+ballsizehalf,objy2+ballsizehalf
Local mx:Int=Int(MouseX())-ballsizehalf
Local my:Int=Int(MouseY())-ballsizehalf
glBegin GL_QUADS
' glTexCoord2i(0,0); glColor4b(0,0,$FF,$40); glVertex2i(mx,my)
' glTexCoord2i(0,1); glColor4b($FF,$FF,$FF,$40); glVertex2i(mx,my+ballsize)
' glTexCoord2i(1,1); glColor4b($0,$0,$0,$40); glVertex2i(mx+ballsize,my+ballsize)
' glTexCoord2i(1,0); glColor4b($FF,$FF,$FF,$40); glVertex2i(mx+ballsize,my)
glTexCoord2f(0,0); glVertex2i(mx,my)
glTexCoord2f(0,1); glVertex2i(mx,my+ballsize)
glTexCoord2f(1,1); glVertex2i(mx+ballsize,my+ballsize)
glTexCoord2f(1,0); glVertex2i(mx+ballsize,my)
glEnd
glDisable(GL_TEXTURE_2D)
glDisable(GL_BLEND)
'DrawImage img1,mx+ballsizehalf,my+ballsizehalf
'SetRotation 0
glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_TRUE)
glPixelZoom(1.0,1.0) 'no zooming
glPixelStorei(GL_PACK_ROW_LENGTH,ballsize) 'row length
glPixelStorei(GL_PACK_ALIGNMENT,4) 'byte alignment
glReadPixels(mx,my,ballsize,ballsize,GL_ALPHA,GL_UNSIGNED_BYTE,where) 'grab alpha into buffer
glRasterPos2i 0,256'mx,my 'Set the position top-left to draw this object at
glPixelStorei(GL_UNPACK_ROW_LENGTH,ballsize)
glPixelStorei(GL_UNPACK_ALIGNMENT,4)
glDrawPixels(ballsize,ballsize,GL_RED,GL_UNSIGNED_BYTE,where) 'Render alpha buffer into the stencil buffer
' 'GL_INDEX_SHIFT
' 'GL_INDEX_OFFSET
' glEnable(GL_STENCIL_TEST) 'Test the stencil
' glStencilFunc(GL_GEQUAL,140,$FF) 'Allow any pixels where the alpha is >=140
' glEnable(GL_BLEND) 'Do blending
' glBlendFunc(GL_SRC_ALPHA,GL_ZERO) 'Multiply source color by the alpha value, ignore dest
' 'glEnable(GL_ALPHA_TEST)
' 'glAlphaFunc(GL_GREATER,0.5)
' 'glEnable(GL_ALPHA_TEST)
' 'glAlphaFunc(GL_GREATER,0.5)
' glColor3b($44,$FF,$88) 'What color to render
' glColorMask True,True,True,False 'Draw in color components only, keep alpha for future operations
' glRasterPos2i 0,my+ballsize 'Set the position top-left to draw this object at
' glBegin GL_QUADS
' glVertex2i(mx,my)
' glVertex2i(mx,my+ballsize)
' glVertex2i(mx+ballsize,my+ballsize)
' glVertex2i(mx+ballsize,my)
' glEnd
' glDisable(GL_STENCIL_TEST)
' glDisable(GL_BLEND)
glFlush()
'old stuff
'glPixelMapusv(GL_PIXEL_MAP_R_TO_R,256,redmap)
'glPixelMapusv(GL_PIXEL_MAP_G_TO_G,256,greenmap)
'glPixelMapusv(GL_PIXEL_MAP_B_TO_B,256,bluemap)
'glPixelZoom(1.0,1.0)
'glPixelTransferi(GL_MAP_COLOR,GL_TRUE)
'glPixelTransferf(GL_RED_SCALE,1.0)
'glPixelTransferf(GL_RED_BIAS,0.0)
'glPixelTransferf(GL_GREEN_SCALE,1.0)
'glPixelTransferf(GL_GREEN_BIAS,0.0)
'glPixelTransferf(GL_BLUE_SCALE,1.0)
'glPixelTransferf(GL_BLUE_BIAS,0.0)
'glRasterPos2i(0,480)
'glDisable(GL_TEXTURE_2D)
'glCopyPixels(0,0,640,480,GL_COLOR)
'glEnable(GL_TEXTURE_2D)
'glPixelTransferi(GL_MAP_COLOR,GL_FALSE)
bglSwapBuffers
' Repeat;Until KeyHit(KEY_SPACE)
Until KeyHit(KEY_ESCAPE)
End
Post: #2
glTexParameter only affects the currently-bound texture. You're calling it before you've bound your texture.
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