226a727f0b
by others. Also make use of the author's own self-test suit. PR: 196161 Approved by: maintainer timeout
103 lines
3.7 KiB
Text
103 lines
3.7 KiB
Text
See https://sourceforge.net/p/openil/patches/41/
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This patch improves alpha-compositing in DevIL.
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--- src-IL/src/il_devil.c (revision 1654)
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+++ src-IL/src/il_devil.c (working copy)
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@@ -665,10 +665,10 @@
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ILuint c;
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ILuint StartX, StartY, StartZ;
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ILboolean DestFlipped = IL_FALSE;
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+ ILboolean DoAlphaBlend = IL_FALSE;
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ILubyte *SrcTemp;
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- ILfloat Back;
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-
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- // Check if the desiination image really exists
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+ ILfloat ResultAlpha;
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+ // Check if the destination image really exists
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if (DestName == 0 || iCurImage == NULL) {
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ilSetError(IL_ILLEGAL_OPERATION);
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return IL_FALSE;
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@@ -680,6 +680,9 @@
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DestFlipped = IL_TRUE;
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ilFlipImage();
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}
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+ //determining destination alpha support
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+ DoAlphaBlend = ilIsEnabled(IL_BLIT_BLEND);
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+
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//DestOrigin = Dest->Origin;
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ilBindImage(Source);
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@@ -688,7 +691,9 @@
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ilSetError(IL_INVALID_PARAM);
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return IL_FALSE;
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}
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-
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+ //determining source alpha support
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+ DoAlphaBlend &= ilIsEnabled(IL_BLIT_BLEND);
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+
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Src = iCurImage;
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//@TODO test if coordinates are inside the images (hard limit for source)
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@@ -737,38 +742,49 @@
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const ILuint SrcIndex = (z+SrcZ)*ConvSizePlane + (y+SrcY)*ConvBps + (x+SrcX)*Dest->Bpp;
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const ILuint DestIndex = (z+DestZ)*Dest->SizeOfPlane + (y+DestY)*Dest->Bps + (x+DestX)*Dest->Bpp;
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const ILuint AlphaIdx = SrcIndex + bpp_without_alpha;
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- ILfloat Front = 0;
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+ ILfloat FrontAlpha = 0; // foreground opacity
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+ ILfloat BackAlpha = 0; // background opacity
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switch (Dest->Type)
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{
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case IL_BYTE:
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case IL_UNSIGNED_BYTE:
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- Front = Converted[AlphaIdx]/((float)IL_MAX_UNSIGNED_BYTE);
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+ FrontAlpha = Converted[AlphaIdx]/((float)IL_MAX_UNSIGNED_BYTE);
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+ BackAlpha = Dest->Data[AlphaIdx]/((float)IL_MAX_UNSIGNED_BYTE);
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break;
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case IL_SHORT:
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case IL_UNSIGNED_SHORT:
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- Front = ((ILshort*)Converted)[AlphaIdx]/((float)IL_MAX_UNSIGNED_SHORT);
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+ FrontAlpha = ((ILshort*)Converted)[AlphaIdx]/((float)IL_MAX_UNSIGNED_SHORT);
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+ BackAlpha = ((ILshort*)Dest->Data)[AlphaIdx]/((float)IL_MAX_UNSIGNED_SHORT);
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break;
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case IL_INT:
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case IL_UNSIGNED_INT:
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- Front = ((ILint*)Converted)[AlphaIdx]/((float)IL_MAX_UNSIGNED_INT);
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+ FrontAlpha = ((ILint*)Converted)[AlphaIdx]/((float)IL_MAX_UNSIGNED_INT);
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+ BackAlpha = ((ILint*)Dest->Data)[AlphaIdx]/((float)IL_MAX_UNSIGNED_INT);
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break;
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case IL_FLOAT:
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- Front = ((ILfloat*)Converted)[AlphaIdx];
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+ FrontAlpha = ((ILfloat*)Converted)[AlphaIdx];
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+ BackAlpha = ((ILfloat*)Dest->Data)[AlphaIdx];
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break;
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case IL_DOUBLE:
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- Front = (ILfloat)(((ILdouble*)Converted)[AlphaIdx]);
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+ FrontAlpha = (ILfloat)(((ILdouble*)Converted)[AlphaIdx]);
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+ BackAlpha = (ILfloat)(((ILdouble*)Dest->Data)[AlphaIdx]);
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break;
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}
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- Back = 1.0f - Front;
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- // In case of Alpha channel, the data is blended. Keeps the original alpha.
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- if (ilIsEnabled(IL_BLIT_BLEND)) {
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+
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+ // In case of Alpha channel, the data is blended.
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+ // Computes composite Alpha
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+ if (DoAlphaBlend)
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+ {
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+ ResultAlpha = FrontAlpha + (1.0f - FrontAlpha) * BackAlpha;
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for (c = 0; c < bpp_without_alpha; c++)
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{
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- Dest->Data[DestIndex + c] =
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- (ILubyte)(Converted[SrcIndex + c] * Front
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- + Dest->Data[DestIndex + c] * Back);
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+ Dest->Data[DestIndex + c] = (ILubyte)( 0.5f +
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+ (Converted[SrcIndex + c] * FrontAlpha +
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+ (1.0f - FrontAlpha) * Dest->Data[DestIndex + c] * BackAlpha)
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+ / ResultAlpha);
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}
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+ Dest->Data[AlphaIdx] = (ILubyte)(0.5f + ResultAlpha * (float)IL_MAX_UNSIGNED_BYTE);
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}
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else {
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for (c = 0; c < Dest->Bpp; c++)
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