Wolfenstein 3-D!

This is a port of Wolf4SDL, which is derived from the original id
software source release. The port runs on top of the SDL plugin
runtime and is loaded as an overlay.

Licensing of the game code is not an issue, as discussed below
(essentially, the Debian project treats Wolf4SDL as GPLv2, with an
email from John Carmack backing it up):

  http://forums.rockbox.org/index.php?topic=52872

Included is a copy of MAME's Yamaha OPL sound chip emulator
(fmopl_gpl.c).  This file was not part of the original Wolf4SDL source
(which includes a non-GPL'd version), but was rather rebased from from
a later MAME source which had been relicensed to GPLv2.

Change-Id: I64c2ba035e0be7e2f49252f40640641416613439

1 files changed, 143 insertions, 0 deletions

diff --git a/apps/plugins/sdl/progs/wolf3d/wl_shade.c b/apps/plugins/sdl/progs/wolf3d/wl_shade.c
new file mode 100644
index 0000000000..3f1d5a7b3f
--- /dev/null
+++ b/apps/plugins/sdl/progs/wolf3d/wl_shade.c
@@ -0,0 +1,143 @@
+#include "version.h"
+
+#ifdef USE_SHADING
+#include "wl_def.h"
+#include "wl_shade.h"
+
+typedef struct {
+    uint8_t destRed, destGreen, destBlue;   // values between 0 and 255
+    uint8_t fogStrength;
+} shadedef_t;
+
+shadedef_t shadeDefs[] = {
+    {   0,   0,   0, LSHADE_NOSHADING },
+    {   0,   0,   0, LSHADE_NORMAL },
+    {   0,   0,   0, LSHADE_FOG },
+    {  40,  40,  40, LSHADE_NORMAL },
+    {  60,  60,  60, LSHADE_FOG }
+};
+
+uint8_t shadetable[SHADE_COUNT][256];
+int LSHADE_flag;
+
+#ifdef USE_FEATUREFLAGS
+
+// The lower 8-bit of the upper left tile of every map determine
+// the used shading definition of shadeDefs.
+static int GetShadeDefID()
+{
+    int shadeID = ffDataTopLeft & 0x00ff;
+    assert(shadeID >= 0 && shadeID < lengthof(shadeDefs));
+    return shadeID;
+}
+
+#else
+
+static int GetShadeDefID()
+{
+    int shadeID;
+    switch(gamestate.episode * 10 + mapon)
+    {
+        case  0: shadeID = 4; break;
+        case  1:
+        case  2:
+        case  6: shadeID = 1; break;
+        case  3: shadeID = 0; break;
+        case  5: shadeID = 2; break;
+        default: shadeID = 3; break;
+    }
+    assert(shadeID >= 0 && shadeID < lengthof(shadeDefs));
+    return shadeID;
+}
+
+#endif
+
+
+// Returns the palette index of the nearest matching color of the
+// given RGB color in given palette
+byte GetColor(byte red, byte green, byte blue, SDL_Color *palette)
+{
+    byte mincol = 0;
+    double mindist = 200000.F, curdist, DRed, DGreen, DBlue;
+
+    SDL_Color *palPtr = palette;
+
+    for(int col = 0; col < 256; col++, palPtr++)
+    {
+        DRed   = (double) (red   - palPtr->r);
+        DGreen = (double) (green - palPtr->g);
+        DBlue  = (double) (blue  - palPtr->b);
+        curdist = DRed * DRed + DGreen * DGreen + DBlue * DBlue;
+        if(curdist < mindist)
+        {
+            mindist = curdist;
+            mincol = (byte) col;
+        }
+    }
+    return mincol;
+}
+
+// Fade all colors in 32 steps down to the destination-RGB
+// (use gray for fogging, black for standard shading)
+void GenerateShadeTable(byte destRed, byte destGreen, byte destBlue,
+                        SDL_Color *palette, int fog)
+{
+    double curRed, curGreen, curBlue, redStep, greenStep, blueStep;
+    SDL_Color *palPtr = palette;
+
+    // Set the fog-flag
+    LSHADE_flag=fog;
+
+    // Color loop
+    for(int i = 0; i < 256; i++, palPtr++)
+    {
+        // Get original palette color
+        curRed   = palPtr->r;
+        curGreen = palPtr->g;
+        curBlue  = palPtr->b;
+
+        // Calculate increment per step
+        redStep   = ((double) destRed   - curRed)   / (SHADE_COUNT + 8);
+        greenStep = ((double) destGreen - curGreen) / (SHADE_COUNT + 8);
+        blueStep  = ((double) destBlue  - curBlue)  / (SHADE_COUNT + 8);
+
+        // Calc color for each shade of the current color
+        for (int shade = 0; shade < SHADE_COUNT; shade++)
+        {
+            shadetable[shade][i] = GetColor((byte) curRed, (byte) curGreen, (byte) curBlue, palette);
+
+            // Inc to next shade
+            curRed   += redStep;
+            curGreen += greenStep;
+            curBlue  += blueStep;
+        }
+    }
+}
+
+void NoShading()
+{
+    for(int shade = 0; shade < SHADE_COUNT; shade++)
+        for(int i = 0; i < 256; i++)
+            shadetable[shade][i] = i;
+}
+
+void InitLevelShadeTable()
+{
+    shadedef_t *shadeDef = &shadeDefs[GetShadeDefID()];
+    if(shadeDef->fogStrength == LSHADE_NOSHADING)
+        NoShading();
+    else
+        GenerateShadeTable(shadeDef->destRed, shadeDef->destGreen, shadeDef->destBlue, gamepal, shadeDef->fogStrength);
+}
+
+int GetShade(int scale)
+{
+    int shade = (scale >> 1) / (((viewwidth * 3) >> 8) + 1 + LSHADE_flag);  // TODO: reconsider this...
+    if(shade > 32) shade = 32;
+    else if(shade < 1) shade = 1;
+    shade = 32 - shade;
+
+    return shade;
+}
+
+#endif