More blend image updates

- Allow the translations that don't make use a blend image to work without requiring a blend image to be present
- Fix TC_RAINBOW not working properly
- TC_METALSONIC now remaps the _blend image to SKINCOLOR_COBALT, then inverts all of the blue, replicating how it works in Software

(cherry picked from commit 74d7f256a7849d0c829177614b37089e2446f86b)

src/hardware/hw_md2.c

@@ -654,12 +654,12 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 	UINT16 w = gpatch->width, h = gpatch->height;
 	UINT32 size = w*h;
 	RGBA_t *image, *blendimage, *cur, blendcolor;
-	UINT8 i;
-
 	UINT8 translation[16]; // First the color index
 	UINT8 cutoff[16]; // Brightness cutoff before using the next color
 	UINT8 translen = 0;
+	UINT8 i;
 
+	blendcolor = V_GetColor(0); // initialize
 	memset(translation, 0, sizeof(translation));
 	memset(cutoff, 0, sizeof(cutoff));
 
@@ -685,7 +685,10 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 
 	image = gpatch->mipmap->grInfo.data;
 	blendimage = blendgpatch->mipmap->grInfo.data;
-	blendcolor = V_GetColor(0); // initialize
+
+	// TC_METALSONIC includes an actual skincolor translation, on top of its flashing.
+	if (skinnum == TC_METALSONIC)
+		color = SKINCOLOR_COBALT;
 
 	if (color != SKINCOLOR_NONE)
 	{
@@ -721,7 +724,7 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 		if (skinnum == TC_BOSS)
 		{
 			// Turn everything below a certain threshold white
-			if ((image->s.red == image->s.green) && (image->s.green == image->s.blue) && image->s.blue <= 82)
+			if ((image->s.red == image->s.green) && (image->s.green == image->s.blue) && image->s.blue < 127)
 			{
 				// Lactozilla: Invert the colors
 				cur->s.red = cur->s.green = cur->s.blue = (255 - image->s.blue);
@@ -735,23 +738,23 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 
 			cur->s.alpha = image->s.alpha;
 		}
-		else if (skinnum == TC_METALSONIC)
+		else if (skinnum == TC_ALLWHITE)
 		{
-			// Turn everything below a certain blue threshold white
+			// Turn everything white
-			if (image->s.red == 0 && image->s.green == 0 && image->s.blue <= 82)
+			cur->s.red = cur->s.green = cur->s.blue = 255;
-			{
+			cur->s.alpha = image->s.alpha;
-				cur->s.red = cur->s.green = cur->s.blue = (255 - image->s.blue);
 		}
 		else
 		{
-				cur->s.red = image->s.red;
+			// Everything below requires a blend image
-				cur->s.green = image->s.green;
+			if (blendimage == NULL)
-				cur->s.blue = image->s.blue;
+			{
+				cur->rgba = image->rgba;
+				goto skippixel;
 			}
 
-			cur->s.alpha = image->s.alpha;
+			// Metal Sonic dash mode
-		}
+			if (skinnum == TC_DASHMODE)
-		else if (skinnum == TC_DASHMODE)
 			{
 				if (image->s.alpha == 0 && blendimage->s.alpha == 0)
 				{
@@ -771,28 +774,29 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 						bcolor.s.red = 255;
 						bcolor.s.green = (blendimage->s.red + blendimage->s.green + blendimage->s.blue) / 3;
 					}
+
 					if (image->s.alpha && image->s.red > image->s.green << 1) // this is pretty arbitrary, but it works well for Metal Sonic
 					{
 						icolor.s.red = image->s.blue;
 						icolor.s.blue = image->s.red;
 					}
+
 					cur->s.red = (ialpha * icolor.s.red + balpha * bcolor.s.red)/255;
 					cur->s.green = (ialpha * icolor.s.green + balpha * bcolor.s.green)/255;
 					cur->s.blue = (ialpha * icolor.s.blue + balpha * bcolor.s.blue)/255;
 					cur->s.alpha = image->s.alpha;
 				}
 			}
-		else if (skinnum == TC_ALLWHITE)
-		{
-			// Turn everything white
-			cur->s.red = cur->s.green = cur->s.blue = 255;
-			cur->s.alpha = image->s.alpha;
-		}
 			else
 			{
+				// All settings that use skincolors!
 				UINT16 brightness;
 
-			I_Assert(translen > 0);
+				if (translen <= 0)
+				{
+					cur->rgba = image->rgba;
+					goto skippixel;
+				}
 
 				// Don't bother with blending the pixel if the alpha of the blend pixel is 0
 				if (skinnum == TC_RAINBOW)
@@ -800,8 +804,7 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 					if (image->s.alpha == 0 && blendimage->s.alpha == 0)
 					{
 						cur->rgba = image->rgba;
-					cur++; image++; blendimage++;
+						goto skippixel;
-					continue;
 					}
 					else
 					{
@@ -817,8 +820,7 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 					if (blendimage->s.alpha == 0)
 					{
 						cur->rgba = image->rgba;
-					cur++; image++; blendimage++;
+						goto skippixel; // for metal sonic blend
-					continue;
 					}
 					else
 					{
@@ -888,20 +890,14 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 						if (m >= d)
 							m = d-1;
 
+						mulmax = 16;
+
 						// calculate the "gradient" multiplier based on how close this color is to the one next in line
 						if (m <= 0 || d <= 0)
-					{
 							mul = 0;
-					}
 						else
-					{
-						mulmax = cutoff[firsti];
-						if (secondi < translen)
-							mulmax -= cutoff[secondi];
-
 							mul = (mulmax-1) - ((m * mulmax) / d);
 					}
-				}
 					else
 					{
 						// Just convert brightness to a skincolor value, use distance to next position to find the gradient multipler
@@ -989,9 +985,29 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 					cur->s.blue = (UINT8)tempcolor;
 					cur->s.alpha = image->s.alpha;
 				}
+
+skippixel:
+
+				// *Now* we can do Metal Sonic's flashing
+				if (skinnum == TC_METALSONIC)
+				{
+					// Blend dark blue into white
+					if (cur->s.alpha > 0 && cur->s.red == 0 && cur->s.green == 0 && cur->s.blue < 255 && cur->s.blue > 31)
+					{
+						// Sal: Invert non-blue
+						cur->s.red = cur->s.green = (255 - cur->s.blue);
+						cur->s.blue = 255;
 					}
 
-		cur++; image++; blendimage++;
+					cur->s.alpha = image->s.alpha;
+				}
+			}
+		}
+
+		cur++; image++;
+
+		if (blendimage != NULL)
+			blendimage++;
 	}
 
 	return;
@@ -1030,6 +1046,14 @@ static void HWR_GetBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch, INT
 	// If here, the blended texture has not been created
 	// So we create it
 
+	if ((blendgpatch && blendgpatch->mipmap->grInfo.format)
+		&& (gpatch->width != blendgpatch->width || gpatch->height != blendgpatch->height))
+	{
+		// Blend image exists, but it's bad.
+		HWD.pfnSetTexture(gpatch->mipmap);
+		return;
+	}
+
 	//BP: WARNING: don't free it manually without clearing the cache of harware renderer
 	//              (it have a liste of mipmap)
 	//    this malloc is cleared in HWR_FreeTextureCache
@@ -1272,11 +1296,9 @@ boolean HWR_DrawModel(gr_vissprite_t *spr)
 			md2_loadBlendTexture(md2);
 
 		if (gpatch && gpatch->mipmap->grInfo.format) // else if meant that if a texture couldn't be loaded, it would just end up using something else's texture
-		{
-			if (md2->blendgrpatch && ((GLPatch_t *)md2->blendgrpatch)->mipmap->grInfo.format
-				&& gpatch->width == ((GLPatch_t *)md2->blendgrpatch)->width && gpatch->height == ((GLPatch_t *)md2->blendgrpatch)->height)
 		{
 			INT32 skinnum = INT32_MAX;
+
 			if ((spr->mobj->flags & (MF_ENEMY|MF_BOSS)) && (spr->mobj->flags2 & MF2_FRET) && !(spr->mobj->flags & MF_GRENADEBOUNCE) && (leveltime & 1)) // Bosses "flash"
 			{
 				if (spr->mobj->type == MT_CYBRAKDEMON || spr->mobj->colorized)
@@ -1307,7 +1329,9 @@ boolean HWR_DrawModel(gr_vissprite_t *spr)
 
 			// Translation or skin number found
 			if (skinnum != INT32_MAX)
+			{
 				HWR_GetBlendedTexture(gpatch, (GLPatch_t *)md2->blendgrpatch, skinnum, spr->colormap, (skincolors_t)spr->mobj->color);
+			}
 			else
 			{
 				// Sorry nothing
@@ -1315,12 +1339,6 @@ boolean HWR_DrawModel(gr_vissprite_t *spr)
 			}
 		}
 		else
-			{
-				// This is safe, since we know the texture has been downloaded
-				HWD.pfnSetTexture(gpatch->mipmap);
-			}
-		}
-		else
 		{
 			// Sprite
 			gpatch = spr->gpatch; //W_CachePatchNum(spr->patchlumpnum, PU_CACHE);