Enable Ken Silverman's voxel drawing code now that he has given us permission to license it as GPL

src/swrenderer/things/r_voxel.h

@@ -1,25 +1,26 @@
-/*
-**  Voxel rendering
-**  Copyright (c) 1998-2016 Randy Heit
-**  Copyright (c) 2016 Magnus Norddahl
-**
-**  This software is provided 'as-is', without any express or implied
-**  warranty.  In no event will the authors be held liable for any damages
-**  arising from the use of this software.
-**
-**  Permission is granted to anyone to use this software for any purpose,
-**  including commercial applications, and to alter it and redistribute it
-**  freely, subject to the following restrictions:
-**
-**  1. The origin of this software must not be misrepresented; you must not
-**     claim that you wrote the original software. If you use this software
-**     in a product, an acknowledgment in the product documentation would be
-**     appreciated but is not required.
-**  2. Altered source versions must be plainly marked as such, and must not be
-**     misrepresented as being the original software.
-**  3. This notice may not be removed or altered from any source distribution.
-**
-*/
+// 
+//---------------------------------------------------------------------------
+//
+// Voxel rendering
+// Copyright(c) 1993 - 1997 Ken Silverman
+// Copyright(c) 1998 - 2016 Randy Heit
+// All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program.  If not, see http://www.gnu.org/licenses/
+//
+//--------------------------------------------------------------------------
+//
 
 #pragma once
 
@@ -77,14 +78,13 @@ namespace swrenderer
 		DAngle Angle = { 0.0 };
 		fixed_t xscale = 0;
 		FVoxel *voxel = nullptr;
+		bool bInMirror = false;
 
 		uint32_t Translation = 0;
 		uint32_t FillColor = 0;
 
 		enum { DVF_OFFSCREEN = 1, DVF_SPANSONLY = 2, DVF_MIRRORED = 4 };
 
-		static void FillBox(RenderThread *thread, SpriteDrawerArgs &drawerargs, DVector3 origin, double extentX, double extentY, int color, short *cliptop, short *clipbottom, bool viewspace, bool pixelstretch);
-
 		static kvxslab_t *GetSlabStart(const FVoxelMipLevel &mip, int x, int y);
 		static kvxslab_t *GetSlabEnd(const FVoxelMipLevel &mip, int x, int y);
 		static kvxslab_t *NextSlab(kvxslab_t *slab);
@@ -95,5 +95,15 @@ namespace swrenderer
 		static int OffscreenBufferWidth;
 		static int OffscreenBufferHeight;
 		static uint8_t *OffscreenColorBuffer;
+
+		void DrawVoxel(
+			RenderThread *thread, SpriteDrawerArgs &drawerargs,
+			const FVector3 &globalpos, FAngle viewangle, const FVector3 &dasprpos, DAngle dasprang, fixed_t daxscale, fixed_t dayscale,
+			FVoxel *voxobj, short *daumost, short *dadmost, int minslabz, int maxslabz, int flags);
+
+		int sgn(int v)
+		{
+			return v < 0 ? -1 : v > 0 ? 1 : 0;
+		}
 	};
 }

src/swrenderer/viewport/r_spritedrawer.cpp

@@ -497,6 +497,17 @@ namespace swrenderer
 		thread->Drawers()->FillColumn(*this);
 	}
 
+	void SpriteDrawerArgs::DrawVoxelColumn(RenderThread *thread, fixed_t vPos, fixed_t vStep, const uint8_t *voxels, int voxelsCount)
+	{
+		dc_iscale = vStep;
+		dc_texturefrac = vPos;
+		dc_texturefracx = 0;
+		dc_source = voxels;
+		dc_source2 = 0;
+		dc_textureheight = voxelsCount;
+		(thread->Drawers()->*colfunc)(*this);
+	}
+
 	void SpriteDrawerArgs::SetDest(int x, int y)
 	{
 		auto viewport = RenderViewport::Instance();

src/swrenderer/viewport/r_spritedrawer.h

@@ -24,6 +24,7 @@ namespace swrenderer
 
 		void DrawMaskedColumn(RenderThread *thread, int x, fixed_t iscale, FTexture *texture, fixed_t column, double spryscale, double sprtopscreen, bool sprflipvert, const short *mfloorclip, const short *mceilingclip, bool unmasked = false);
 		void FillColumn(RenderThread *thread);
+		void DrawVoxelColumn(RenderThread *thread, fixed_t vPos, fixed_t vStep, const uint8_t *voxels, int voxelsCount);
 
 		uint8_t *Dest() const { return dc_dest; }
 		int DestY() const { return dc_dest_y; }

src/swrenderer/viewport/r_viewport.cpp

@@ -156,6 +156,9 @@ namespace swrenderer
 		FocalLengthX = CenterX / FocalTangent;
 		FocalLengthY = FocalLengthX * YaspectMul;
 
+		// This is 1/FocalTangent before the widescreen extension of FOV.
+		viewingrangerecip = FLOAT2FIXED(1. / tan(FieldOfView.Radians() / 2));
+
 		// Now generate xtoviewangle for sky texture mapping.
 		// [RH] Do not generate viewangletox, because texture mapping is no
 		// longer done with trig, so it's not needed.

src/swrenderer/viewport/r_viewport.h

@@ -43,6 +43,9 @@ namespace swrenderer
 		double globaluclip = 0.0;
 		double globaldclip = 0.0;
 
+		fixed_t viewingrangerecip = 0;
+		double BaseYaspectMul = 0.0; // yaspectmul without a forced aspect ratio
+
 		// The xtoviewangleangle[] table maps a screen pixel
 		// to the lowest viewangle that maps back to x ranges
 		// from clipangle to -clipangle.
@@ -70,7 +73,5 @@ namespace swrenderer
 	private:
 		void InitTextureMapping();
 		void SetupBuffer();
-		
-		double BaseYaspectMul = 0.0; // yaspectmul without a forced aspect ratio
 	};
 }