Let equation slopes be read from textmaps.

src/p_setup.c

@@ -1501,6 +1501,22 @@ typedef struct textmap_colormap_s {
 
 textmap_colormap_t textmap_colormap = { false, 0, 25, 0, 25, 0, 31, 0 };
 
+typedef enum
+{
+    PD_A = 1,
+    PD_B = 1<<1,
+    PD_C = 1<<2,
+    PD_D = 1<<3,
+} planedef_t;
+
+typedef struct textmap_plane_s {
+    UINT8 defined;
+    fixed_t a, b, c, d;
+} textmap_plane_t;
+
+textmap_plane_t textmap_planefloor = {0, 0, 0, 0, 0};
+textmap_plane_t textmap_planeceiling = {0, 0, 0, 0, 0};
+
 static void ParseTextmapSectorParameter(UINT32 i, char *param, char *val)
 {
 	if (fastcmp(param, "heightfloor"))
@@ -1539,6 +1555,46 @@ static void ParseTextmapSectorParameter(UINT32 i, char *param, char *val)
 		sectors[i].floorpic_angle = FixedAngle(FLOAT_TO_FIXED(atof(val)));
 	else if (fastcmp(param, "rotationceiling"))
 		sectors[i].ceilingpic_angle = FixedAngle(FLOAT_TO_FIXED(atof(val)));
+	else if (fastcmp(param, "floorplane_a"))
+	{
+		textmap_planefloor.defined |= PD_A;
+		textmap_planefloor.a = FLOAT_TO_FIXED(atof(val));
+	}
+	else if (fastcmp(param, "floorplane_b"))
+	{
+		textmap_planefloor.defined |= PD_B;
+		textmap_planefloor.a = FLOAT_TO_FIXED(atof(val));
+	}
+	else if (fastcmp(param, "floorplane_c"))
+	{
+		textmap_planefloor.defined |= PD_C;
+		textmap_planefloor.a = FLOAT_TO_FIXED(atof(val));
+	}
+	else if (fastcmp(param, "floorplane_d"))
+	{
+		textmap_planefloor.defined |= PD_D;
+		textmap_planefloor.a = FLOAT_TO_FIXED(atof(val));
+	}
+	else if (fastcmp(param, "ceilingplane_a"))
+	{
+		textmap_planeceiling.defined |= PD_A;
+		textmap_planeceiling.a = FLOAT_TO_FIXED(atof(val));
+	}
+	else if (fastcmp(param, "ceilingplane_b"))
+	{
+		textmap_planeceiling.defined |= PD_B;
+		textmap_planeceiling.a = FLOAT_TO_FIXED(atof(val));
+	}
+	else if (fastcmp(param, "ceilingplane_c"))
+	{
+		textmap_planeceiling.defined |= PD_C;
+		textmap_planeceiling.a = FLOAT_TO_FIXED(atof(val));
+	}
+	else if (fastcmp(param, "ceilingplane_d"))
+	{
+		textmap_planeceiling.defined |= PD_D;
+		textmap_planeceiling.a = FLOAT_TO_FIXED(atof(val));
+	}
 	else if (fastcmp(param, "lightcolor"))
 	{
 		textmap_colormap.used = true;
@@ -1868,6 +1924,10 @@ static void P_LoadTextmap(void)
 		textmap_colormap.fadestart = 0;
 		textmap_colormap.fadeend = 31;
 		textmap_colormap.flags = 0;
+
+		textmap_planefloor.defined = 0;
+		textmap_planeceiling.defined = 0;
+
 		TextmapParse(sectorsPos[i], i, ParseTextmapSectorParameter);
 
 		P_InitializeSector(sc);
@@ -1877,6 +1937,19 @@ static void P_LoadTextmap(void)
 			INT32 fadergba = P_ColorToRGBA(textmap_colormap.fadecolor, textmap_colormap.fadealpha);
 			sc->extra_colormap = sc->spawn_extra_colormap = R_CreateColormap(rgba, fadergba, textmap_colormap.fadestart, textmap_colormap.fadeend, textmap_colormap.flags);
 		}
+
+		if (textmap_planefloor.defined == (PD_A|PD_B|PD_C|PD_D))
+        {
+			sc->f_slope = MakeViaEquationConstants(textmap_planefloor.a, textmap_planefloor.b, textmap_planefloor.c, textmap_planefloor.d);
+			sc->hasslope = true;
+        }
+
+		if (textmap_planeceiling.defined == (PD_A|PD_B|PD_C|PD_D))
+        {
+			sc->c_slope = MakeViaEquationConstants(textmap_planeceiling.a, textmap_planeceiling.b, textmap_planeceiling.c, textmap_planeceiling.d);
+			sc->hasslope = true;
+        }
+
 		TextmapFixFlatOffsets(sc);
 	}