| Iodiplin |
Posted - Aug 27 2004 : 6:53:59 PM
This is an error I have known of for quite some time, but I've never worried about it. Now that I'm writing a game with my engine, I need the bug fixed.
Here's the problem:
When initializing the vertices for the images I'm rendering, I obviously must set the texture coordinates. This works fine, in some cases.
My image is not square, therefore I put it in a bitmap whose dementions are square in squares of 2. When I render the entire bitmap, with or without transparency, and all things at normal values (no flipping, no cropping), it looks just fune:
However, when I flip it, it doesn't work out so well:
As you can see, after being flipped horizontally, a column of pixels has been taken from the right side of the image and rendered on the left side.
The same thing happens when it is flipped vertically:
When both horizontal and vertical flipping are applied, the you get glitches on both ends:
I did some specialized debeugging and found that if I subtracted two pixel rows/columns from the texture coordinates the problem was fixed. (Two pixels in texture coordinates found by 1 / TextureSize * 2.)
However, when I then set up the geomitry with the actual size of the image (so that it cropped the render to the size 41x15), it produced an image with 2 rows/columns of pixels missing on one the opposite side of the flip.
Like this (flipped both horizontally and vertically):
So, I'm stuck, I can't think of any reason why this is happening besides some esoteric glitch in my texture coordinate calculations.
My Initialize Lit Geometry function is supplied below. I hope it is commented enough that you can understand what's going on.
Public Function InitLitGeom(Vertices() As VERTEX_LIT, X As Single, Y As Single, TextureDesc As D3DSURFACE_DESC, Optional Width As Single, Optional Height As Single, Optional SrcX As Single, Optional SrcY As Single, Optional SrcWidth As Single, Optional SrcHeight As Single, Optional Angle As Single, Optional FlipHorizontal As Boolean, Optional FlipVertical As Boolean, Optional Color0 As Long, Optional Color1 As Long, Optional Color2 As Long, Optional Color3 As Long, Optional DefaultColor As Long = COL_BLACK, Optional Spec0 As Long, Optional Spec1 As Long, Optional Spec2 As Long, Optional Spec3 As Long, Optional DefaultSpec As Long) As Long
Dim XCenter As Single Dim YCenter As Single Dim UsedX As Single Dim UsedY As Single
Dim SinAngle As Double Dim CosAngle As Double
Dim Src As RECT Dim Dest As RECT
Dim TwoPixX As Single Dim TwoPixY As Single
On Local Error GoTo ErrorHandler
If SrcWidth = 0 Then SrcWidth = TextureDesc.Width
If SrcHeight = 0 Then SrcHeight = TextureDesc.Height
If Width = 0 Then Width = SrcWidth
If Height = 0 Then Height = SrcHeight
With Src
.Left = SrcX
.Top = SrcY
.Right = SrcX + SrcWidth
.Bottom = SrcY + SrcHeight
End With
With Dest
.Left = X
.Top = Y
.Right = X + Width
.Bottom = Y + Height
End With
If Color0 = 0 Then Color0 = DefaultColor
If Color1 = 0 Then Color1 = DefaultColor
If Color2 = 0 Then Color2 = DefaultColor
If Color3 = 0 Then Color3 = DefaultColor
If Spec0 = 0 Then Spec0 = DefaultSpec
If Spec1 = 0 Then Spec1 = DefaultSpec
If Spec2 = 0 Then Spec2 = DefaultSpec
If Spec3 = 0 Then Spec3 = DefaultSpec
TwoPixX = 1 / TextureDesc.Width
TwoPixX = TwoPixX + TwoPixX
TwoPixY = 1 / TextureDesc.Height
TwoPixY = TwoPixY + TwoPixY
If Angle = 0 Then
UsedX = Dest.Left
UsedY = Dest.Top
Else
XCenter = Dest.Left + (Dest.Right - Dest.Left - 1) * 0.5
YCenter = Dest.Top + (Dest.Bottom - Dest.Top - 1) * 0.5
SinAngle = Sin(Angle + RightAngle)
CosAngle = Cos(Angle + RightAngle)
UsedX = XCenter + (Dest.Left - XCenter) * SinAngle + (Dest.Top - YCenter) * CosAngle
UsedY = YCenter + (Dest.Top - YCenter) * SinAngle - (Dest.Left - XCenter) * CosAngle
End If
If FlipHorizontal = True And FlipVertical = False Then
Vertices(0) = CreateTLVertex(UsedX, UsedY, 0, 1, Color0, Spec0, (Src.Right + 1) / TextureDesc.Width - TwoPixX, Src.Top / TextureDesc.Height)
ElseIf FlipVertical = True And FlipHorizontal = False Then
Vertices(0) = CreateTLVertex(UsedX, UsedY, 0, 1, Color0, Spec0, Src.Left / TextureDesc.Width, (Src.Bottom + 1) / TextureDesc.Height - TwoPixY)
ElseIf FlipHorizontal = True And FlipVertical = True Then
Vertices(0) = CreateTLVertex(UsedX, UsedY, 0, 1, Color0, Spec0, (Src.Right + 1) / TextureDesc.Width - TwoPixX, (Src.Bottom) / TextureDesc.Height - TwoPixY)
Else
Vertices(0) = CreateTLVertex(UsedX, UsedY, 0, 1, Color0, Spec0, Src.Left / TextureDesc.Width, Src.Top / TextureDesc.Height)
End If
If Angle = 0 Then
UsedX = Dest.Right
UsedY = Dest.Top
Else
UsedX = XCenter + (Dest.Right - XCenter) * SinAngle + (Dest.Top - YCenter) * CosAngle
UsedY = YCenter + (Dest.Top - YCenter) * SinAngle - (Dest.Right - XCenter) * CosAngle
End If
If FlipHorizontal = True And FlipVertical = False Then
Vertices(1) = CreateTLVertex(UsedX, UsedY, 0, 1, Color1, Spec1, Src.Left / TextureDesc.Width - TwoPixX, Src.Top / TextureDesc.Height)
ElseIf FlipVertical = True And FlipHorizontal = False Then
Vertices(1) = CreateTLVertex(UsedX, UsedY, 0, 1, Color1, Spec1, (Src.Right + 1) / TextureDesc.Width, (Src.Bottom + 1) / TextureDesc.Height - TwoPixY)
ElseIf FlipHorizontal = True And FlipVertical = True Then
Vertices(1) = CreateTLVertex(UsedX, UsedY, 0, 1, Color1, Spec1, Src.Left / TextureDesc.Width - TwoPixX, (Src.Bottom + 1) / TextureDesc.Height - TwoPixY)
Else
Vertices(1) = CreateTLVertex(UsedX, UsedY, 0, 1, Color1, Spec1, (Src.Right + 1) / TextureDesc.Width, Src.Top / TextureDesc.Height)
End If
If Angle = 0 Then
UsedX = Dest.Left
UsedY = Dest.Bottom
Else
UsedX = XCenter + (Dest.Left - XCenter) * SinAngle + (Dest.Bottom - YCenter) * CosAngle
UsedY = YCenter + (Dest.Bottom - YCenter) * SinAngle - (Dest.Left - XCenter) * CosAngle
End If
If FlipHorizontal = True And FlipVertical = False Then
Vertices(2) = CreateTLVertex(UsedX, UsedY, 0, 1, Color2, Spec2, (Src.Right + 1) / TextureDesc.Width - TwoPixX, (Src.Bottom + 1) / TextureDesc.Height)
ElseIf FlipVertical = True And FlipHorizontal = False Then
Vertices(2) = CreateTLVertex(UsedX, UsedY, 0, 1, Color2, Spec2, Src.Left / TextureDesc.Width, Src.Top / TextureDesc.Height - TwoPixY)
ElseIf FlipHorizontal = True And FlipVertical = True Then
Vertices(2) = CreateTLVertex(UsedX, UsedY, 0, 1, Color2, Spec2, (Src.Right + 1) / TextureDesc.Width - TwoPixX, Src.Top / TextureDesc.Height - TwoPixY)
Else
Vertices(2) = CreateTLVertex(UsedX, UsedY, 0, 1, Color2, Spec2, Src.Left / TextureDesc.Width, (Src.Bottom + 1) / TextureDesc.Height)
End If
If Angle = 0 Then
UsedX = Dest.Right
UsedY = Dest.Bottom
Else
UsedX = XCenter + (Dest.Right - XCenter) * SinAngle + (Dest.Bottom - YCenter) * CosAngle
UsedY = YCenter + (Dest.Bottom - YCenter) * SinAngle - (Dest.Right - XCenter) * CosAngle
End If
If FlipHorizontal = True And FlipVertical = False Then
Vertices(3) = CreateTLVertex(UsedX, UsedY, 0, 1, Color3, Spec3, Src.Left / TextureDesc.Width - TwoPixX, (Src.Bottom + 1) / TextureDesc.Height)
ElseIf FlipVertical = True And FlipHorizontal = False Then
Vertices(3) = CreateTLVertex(UsedX, UsedY, 0, 1, Color3, Spec3, (Src.Right + 1) / TextureDesc.Width, Src.Top / TextureDesc.Height - TwoPixY)
ElseIf FlipHorizontal = True And FlipVertical = True Then
Vertices(3) = CreateTLVertex(UsedX, UsedY, 0, 1, Color3, Spec3, Src.Left / TextureDesc.Width - TwoPixX, Src.Top / TextureDesc.Height - TwoPixY)
Else
Vertices(3) = CreateTLVertex(UsedX, UsedY, 0, 1, Color3, Spec3, (Src.Right + 1) / TextureDesc.Width, (Src.Bottom + 1) / TextureDesc.Height)
End If
ErrorHandler:
InitLitGeom = Err.Number
End Function
Thank you so much for your assistance. |
| Iodiplin |
Posted - Aug 29 2004 : 2:55:49 PM
My textures are all square and all dimensions (of the bitmaps) are in squares of two.
Thanks a lot! |
| Almar |
Posted - Aug 29 2004 : 07:48:56 AM
- Make your textures like 16x32 or 64x64, 128x128, etc.
- Turn off filtering, or texture wrapping. It's something with that. I had it too with my Elements contest entry, until I finally figured out the problem.
|
| Eric Coleman |
Posted - Aug 28 2004 : 2:41:17 PM
quote:
Originally posted by sdw
-> On another subject -> Eric, if you're reading, the 'Preview Reply' window does not display the code tags properly, unless that's intended to be that way. I am just making sure you know.
The code formatting is a bit of a hack that I added to the forum. I am aware that the preview function doesn't display the code formatting properly. I'm so busy working on other parts of VBgamer that it's not really a priority to fix. And hopefully I'll be able to get rid of this forum and use the custom forum that the news comments are now using. |
| Eric Coleman |
Posted - Aug 28 2004 : 2:37:55 PM
Open the DirectX 8 help file and follow this directory structure...
DirectX 8.1 (Visual Basic)
> DirectX Graphics
>> Programmers Guide
>>> Using Direct 3D
>>>> Textures
>>>>> Texture Coordinates
>>>>>> Directly Mapping Texels to Pixels
It gives the formula for converting texture coordinates into texel coordinates. It seems you need to calculate the correct texture coordinate, so the formula that you would use would be:
u = (Tx + 0.5) / Mx
v = (Ty + 0.5) / My
And this generates single precision (float) coordinates, which is what you need. |
| Iodiplin |
Posted - Aug 28 2004 : 10:50:49 AM
Actually, with a little more testing, I think I might be able to get this to work. Thanks! |
| Iodiplin |
Posted - Aug 28 2004 : 10:26:36 AM
I tested it, and got the same results as last time. There must be something wrong with the way I'm calling it. Would you mind e-mailing me your project (if it's small) or maybe just give me an example of how you call it and use it?
I'm a desperate man as of now, I'll take anything I can get to clear this up. Thank you very much.
P.S. I was able to get around my problem in some cercumstances by offsetting the image in the bitmap by 1 pixel. However, this made cropping worse, but eliminated the extra columns/rows of pixels when flipping (unclipped). |
| sdw |
Posted - Aug 28 2004 : 12:32:04 AM
Hmm, it seems when I tested it I was not using it to crop an image. The subtraction of 1 from the SrcXRight and SrcYBottom is not needed. I again modified the function:
Public Sub DrawObj(TexID As Long, DestX As Single, DestY As Single, SrcWidth As Integer, SrcHeight As Integer, Optional SrcX As Single, Optional SrcY As Single, Optional DestWidth As Integer, Optional DestHeight As Integer, Optional Color As Long, Optional Specular As Long, Optional Alphablend As Boolean, Optional Angle As Single)
Dim TempVerts(3) As TLVERTEX
Dim lDim As Long
Dim DestXRight As Single
Dim DestYBottom As Single
Dim SrcXRight As Single
Dim SrcYBottom As Single
Dim XCor As Single
Dim YCor As Single
Dim XCenter As Single
Dim YCenter As Single
If Not Color Then Color = RGB(255, 255, 255)
If DestWidth = 0 Then DestWidth = SrcWidth
If DestHeight = 0 Then DestHeight = SrcHeight
XCenter = DestX + (DestWidth / 2)
YCenter = DestY + (DestHeight / 2)
DestXRight = DestX + DestWidth
DestYBottom = DestY + DestHeight
SrcXRight = SrcX + SrcWidth
SrcYBottom = SrcY + SrcHeight
lDim = Textures(TexID).lDimension
If Angle = 0 Then
XCor = DestX
YCor = DestY
Else
XCor = XCenter + RotateX(DestX - XCenter, DestY - YCenter, Angle)
YCor = YCenter + RotateY(DestX - XCenter, DestY - YCenter, Angle)
End If
TempVerts(0) = CreateTLVertex(XCor, YCor, 0, 1, Color, Specular, SrcX / lDim, SrcY / lDim)
If Angle = 0 Then
XCor = DestXRight
YCor = DestY
Else
XCor = XCenter + RotateX(DestXRight - XCenter, DestY - YCenter, Angle)
YCor = YCenter + RotateY(DestXRight - XCenter, DestY - YCenter, Angle)
End If
TempVerts(1) = CreateTLVertex(XCor, YCor, 0, 1, Color, Specular, SrcXRight / lDim, SrcY / lDim)
If Angle = 0 Then
XCor = DestX
YCor = DestYBottom
Else
XCor = XCenter + RotateX(DestX - XCenter, DestYBottom - YCenter, Angle)
YCor = YCenter + RotateY(DestX - XCenter, DestYBottom - YCenter, Angle)
End If
TempVerts(2) = CreateTLVertex(XCor, YCor, 0, 1, Color, Specular, SrcX / lDim, SrcYBottom / lDim)
If Angle = 0 Then
XCor = DestXRight
YCor = DestYBottom
Else
XCor = XCenter + RotateX(DestXRight - XCenter, DestYBottom - YCenter, Angle)
YCor = YCenter + RotateY(DestXRight - XCenter, DestYBottom - YCenter, Angle)
End If
TempVerts(3) = CreateTLVertex(XCor, YCor, 0, 1, Color, Specular, SrcXRight / lDim, SrcYBottom / lDim)
Dev.SetTexture 0, Textures(TexID).D3DTexture
If (D3DCaps.TextureCaps And D3DPTEXTURECAPS_ALPHA) Then
Dev.SetRenderState D3DRS_ALPHABLENDENABLE, True
If Alphablend = True Then
Dev.SetRenderState D3DRS_SRCBLEND, D3DBLEND_ONE
Dev.SetRenderState D3DRS_DESTBLEND, D3DBLEND_ONE
Else
Dev.SetRenderState D3DRS_SRCBLEND, D3DBLEND_SRCALPHA
Dev.SetRenderState D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA
End If
End If
Dev.DrawPrimitiveUP D3DPT_TRIANGLESTRIP, 2, TempVerts(0), Len(TempVerts(0))
If Dev.GetRenderState(D3DRS_ALPHABLENDENABLE) Then
Dev.SetRenderState D3DRS_ALPHABLENDENABLE, 0
End If
End Sub
I tested it and it seems to work, hopefully for you as well. I'm going to be needing to use this function too :)
-> On another subject -> Eric, if you're reading, the 'Preview Reply' window does not display the code tags properly, unless that's intended to be that way. I am just making sure you know. |
| Iodiplin |
Posted - Aug 27 2004 : 8:51:16 PM
I used your function to render my image with cropping (no flipping) and it added an extra column of pixels at the left and cut of the tips of the bottom and end.
Perhaps I'm just using it incorrectly. Any ideas?
EDIT: Does anyone have any working projects I can download to see the whole thing working? |
| Iodiplin |
Posted - Aug 27 2004 : 8:18:05 PM
Hey thanks! I'll see what I can do with your code. |
| sdw |
Posted - Aug 27 2004 : 7:57:16 PM
For one, use some other variable for TextureDesc.Width and TextureDesc.Height, they're the same value and using something like TextureDimension would make it more readable. Same thing for the TwoPixY and TwoPixX deal, except I would get rid of those altogether. That center doesn't look right, it should be something like:
XCenter = Dest.Left + (Width / 2)
YCenter = Dest.Top + (Height /2)
Also everywhere there's a (Src.Right + 1) and (Src.Bottom + 1) should be the opposite: (Src.Right - 1) and (Src.Bottom - 1)
I remember fixing this function up a while ago, and I think I got it to work nicely, except that I never had it flip the image. If you like you can look at the function:
Public Sub DrawObj(TexID As Long, DestX As Single, DestY As Single, SrcWidth As Integer, SrcHeight As Integer, Optional SrcX As Single, Optional SrcY As Single, Optional DestWidth As Integer, Optional DestHeight As Integer, Optional Color As Long, Optional Specular As Long, Optional Alphablend As Boolean, Optional Angle As Single)
Dim TempVerts(3) As TLVERTEX
Dim lDim As Long
Dim DestXRight As Single
Dim DestYBottom As Single
Dim SrcXRight As Single
Dim SrcYBottom As Single
Dim XCor As Single
Dim YCor As Single
Dim XCenter As Single
Dim YCenter As Single
If DestWidth = 0 Then DestWidth = SrcWidth
If DestHeight = 0 Then DestHeight = SrcHeight
XCenter = DestX + (DestWidth / 2)
YCenter = DestY + (DestHeight / 2)
DestXRight = DestX + DestWidth
DestYBottom = DestY + DestHeight
SrcXRight = SrcX + SrcWidth
SrcYBottom = SrcY + SrcHeight
lDim = Textures(TexID).lDimension
If Angle = 0 Then
XCor = DestX
YCor = DestY
Else
XCor = XCenter + RotateX(DestX - XCenter, DestY - YCenter, Angle)
YCor = YCenter + RotateY(DestX - XCenter, DestY - YCenter, Angle)
End If
TempVerts(0) = CreateTLVertex(XCor, YCor, 0, 1, Color, Specular, SrcX / lDim, SrcY / lDim)
If Angle = 0 Then
XCor = DestXRight
YCor = DestY
Else
XCor = XCenter + RotateX(DestXRight - XCenter, DestY - YCenter, Angle)
YCor = YCenter + RotateY(DestXRight - XCenter, DestY - YCenter, Angle)
End If
TempVerts(1) = CreateTLVertex(XCor, YCor, 0, 1, Color, Specular, (SrcXRight - 1) / lDim, SrcY / lDim)
If Angle = 0 Then
XCor = DestX
YCor = DestYBottom
Else
XCor = XCenter + RotateX(DestX - XCenter, DestYBottom - YCenter, Angle)
YCor = YCenter + RotateY(DestX - XCenter, DestYBottom - YCenter, Angle)
End If
TempVerts(2) = CreateTLVertex(XCor, YCor, 0, 1, Color, Specular, SrcX / lDim, (SrcYBottom - 1) / lDim)
If Angle = 0 Then
XCor = DestXRight
YCor = DestYBottom
Else
XCor = XCenter + RotateX(DestXRight - XCenter, DestYBottom - YCenter, Angle)
YCor = YCenter + RotateY(DestXRight - XCenter, DestYBottom - YCenter, Angle)
End If
TempVerts(3) = CreateTLVertex(XCor, YCor, 0, 1, Color, Specular, (SrcXRight - 1) / lDim, (SrcYBottom - 1) / lDim)
Dev.SetTexture 0, Textures(TexID).D3DTexture
If (D3DCaps.TextureCaps And D3DPTEXTURECAPS_ALPHA) Then
Dev.SetRenderState D3DRS_ALPHABLENDENABLE, True
If Alphablend = True Then
Dev.SetRenderState D3DRS_SRCBLEND, D3DBLEND_ONE
Dev.SetRenderState D3DRS_DESTBLEND, D3DBLEND_ONE
Else
Dev.SetRenderState D3DRS_SRCBLEND, D3DBLEND_SRCALPHA
Dev.SetRenderState D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA
End If
End If
Dev.DrawPrimitiveUP D3DPT_TRIANGLESTRIP, 2, TempVerts(0), Len(TempVerts(0))
If Dev.GetRenderState(D3DRS_ALPHABLENDENABLE) Then
Dev.SetRenderState D3DRS_ALPHABLENDENABLE, 0
End If
End Sub
Public Function RotateX(X As Single, Y As Single, Angle As Single) As Single
Dim tx As Single, TAngle As Single
TAngle = Angle * (Pi / 180)
tx = X * Cos(TAngle) - Y * Sin(TAngle)
RotateX = tx
End Function
Public Function RotateY(X As Single, Y As Single, Angle As Single) As Single
Dim ty As Single, TAngle As Single
TAngle = Angle * (Pi / 180)
ty = Y * Cos(TAngle) + X * Sin(TAngle)
RotateY = ty
End Function
I think those rotation functions are from the dabooda engine. If you add your flipping code to that then it might get you what you want. |
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