Add an option for mosaic affine rendering

Currently software only; would require a shader or more "involved" solution for OpenGL

src/hardware/hw_glob.h

@@ -43,12 +43,6 @@ typedef struct
 	float z;
 } polyvertex_t;
 
-typedef struct
-{
-	float x;
-	float y;
-} f_vector2_t;
-
 // a convex 'plane' polygon, clockwise order
 typedef struct
 {

src/m_fixed.h

@@ -351,6 +351,13 @@ struct vector2_t
 	fixed_t y;
 };
 
+// Floating-point version, used sparingly, primarily in rendering
+struct f_vector2_t
+{
+	float x;
+	float y;
+};
+
 vector2_t *FV2_Load(vector2_t *vec, fixed_t x, fixed_t y);
 vector2_t *FV2_UnLoad(vector2_t *vec, fixed_t *x, fixed_t *y);
 vector2_t *FV2_Copy(vector2_t *a_o, const vector2_t *a_i);

src/r_defs.h

@@ -1168,6 +1168,7 @@ typedef struct
 	affine_t affine;
 	vector2_t affineoffset;
 	fixed_t affineystep;
+	f_vector2_t affinemosaic; // Truncates how columndrawers "move" across the screen
 	fixed_t frac;
 } drawcolumndata_t;
 

src/r_draw_column.cpp

@@ -635,19 +635,50 @@ static void R_DrawAffineColumnTemplate(drawcolumndata_t *dc)
 
 		//I_OutputMsg("xdiff: %f, ydiff: %f\n", FIXED_TO_FLOAT(xdiff), FIXED_TO_FLOAT(ydiff));
 
+		// If we're smaller than usual, mosaic isn't necessary.
+
+		const float y_mosaic = std::max(1.0f, dc->affinemosaic.y);
+		const float x_mosaic = std::max(1.0f, dc->affinemosaic.x);
+
+		const boolean mosaic_on = cv_affinemosaic.value;
+		const boolean xmosaic_on = (FLOAT_TO_FIXED(x_mosaic) > FRACUNIT);
+		const boolean ymosaic_on = (FLOAT_TO_FIXED(y_mosaic) > FRACUNIT);
+
+		fixed_t usefrac = dc->frac;
+
+		if (mosaic_on && xmosaic_on)
+		{
+			usefrac = FLOAT_TO_FIXED(static_cast<INT32>(FIXED_TO_FLOAT(dc->frac) / x_mosaic) * x_mosaic);
+		}
+
+		float ypx = 0.0f;
+
 		// yoinked from NovaSquirrel's mode 7 0preview
 		// ...which is in turn yoinked from Mesen's S-PPU code
 		// i can't do matrix math to save my life :face_holding_back_tears:
 		// (m7xofs and m7yofs are already factored in by destbase)
-		fixed_t ux = FixedMul(b, -cyy) + FixedMul(a, -cxx) + FixedMul(a, dc->frac) + cx;
-		fixed_t uy = FixedMul(d, -cyy) + FixedMul(c, -cxx) + FixedMul(c, dc->frac) + cy;
+		fixed_t ux = FixedMul(b, -cyy) + FixedMul(a, -cxx) + FixedMul(a, usefrac) + cx;
+		fixed_t uy = FixedMul(d, -cyy) + FixedMul(c, -cxx) + FixedMul(c, usefrac) + cy;
+		float ux_base = FIXED_TO_FLOAT(ux);
+		float uy_base = FIXED_TO_FLOAT(uy);
+		float f_b = FIXED_TO_FLOAT(FixedMul(b, ystep_delta));
+		float f_d = FIXED_TO_FLOAT(FixedMul(d, ystep_delta));
 
 		for (; count > 0; dest += stride, --count)
 		{
+			ypx += 1.0f;
+
 			const INT32 srcx = ux >> FRACBITS;
 			const INT32 srcy = (vflip) ? (ph - (uy >> FRACBITS)) : (uy >> FRACBITS);
-			ux += FixedMul(b, ystep_delta);
-			uy += FixedMul(d, ystep_delta);
+			INT32 y_real = static_cast<INT32>(ypx);
+
+			if (mosaic_on && ymosaic_on)
+			{
+				y_real = (static_cast<INT32>(ypx / y_mosaic) * y_mosaic);
+			}
+
+			ux = FLOAT_TO_FIXED(ux_base + (f_b * y_real));
+			uy = FLOAT_TO_FIXED(uy_base + (f_d * y_real));
 
 			if (srcx < 0 || srcx >= pw || srcy < 0 || srcy >= ph)
 			{

src/r_main.cpp

@@ -200,6 +200,7 @@ consvar_t cv_nulldrifttilt = CVAR_INIT ("nulldrifttilt", "On", CV_SAVE, CV_OnOff
 consvar_t cv_fakerollangle = CVAR_INIT ("fakerollangle", "Off", CV_SAVE, CV_OnOff, NULL);
 
 consvar_t cv_affineprescale = CVAR_INIT ("affineprescale", "Off", CV_SAVE, CV_OnOff, NULL);
+consvar_t cv_affinemosaic = CVAR_INIT ("affinemosaic", "Off", CV_SAVE, CV_OnOff, NULL);
 
 static CV_PossibleValue_t affineangle_cons_t[] = {{0, "MIN"}, {360 * FRACUNIT, "MAX"}, {0, NULL}};
 static CV_PossibleValue_t affinetest_cons_t[] = {{0, "Off"}, {1, "On"}, {2, "Auto"}, {0, NULL}};
@@ -1813,6 +1814,7 @@ void R_RegisterEngineStuff(void)
 	CV_RegisterVar(&cv_nulldrifttilt);
 	CV_RegisterVar(&cv_fakerollangle);
 	CV_RegisterVar(&cv_affineprescale);
+	CV_RegisterVar(&cv_affinemosaic);
 
 	CV_RegisterVar(&cv_showhud);
 	CV_RegisterVar(&cv_translucenthud);

src/r_main.h

@@ -162,7 +162,7 @@ extern consvar_t cv_sliptidetilt;
 extern consvar_t cv_nulldriftefx, cv_nulldrifttilt;
 
 extern consvar_t cv_fakerollangle;
-extern consvar_t cv_affineprescale;
+extern consvar_t cv_affineprescale, cv_affinemosaic;
 
 // debugging
 

src/r_things.cpp

@@ -1182,6 +1182,9 @@ static void R_DrawVisSprite(vissprite_t *vis)
 		dc.affineoffset.x = vis->affine.offset.x;
 		dc.affineoffset.y = vis->affine.offset.y;
 
+		dc.affinemosaic.x = vis->affine.mosaic.x;
+		dc.affinemosaic.y = vis->affine.mosaic.y;
+
 		R_CopyAffineBounds(&vis->affine.bounds, &dc.affinebound);
 
 		fixed_t fixed_ylen = (FRACUNIT*dc.affinebound.ylen);
@@ -2081,6 +2084,7 @@ static void R_ProjectSprite(mobj_t *thing)
 	vector2_t affine_scale = {0};
 	vector2_t affine_distscale = {0};
 	vector2_t affine_pivotoffsetdiff = {0};
+	f_vector2_t affine_mosaic = {.x = 1.0f, .y = 1.0f};
 
 	if (R_IsOverlayingSMonitorPlayer(thing))
 	{
@@ -2355,6 +2359,9 @@ static void R_ProjectSprite(mobj_t *thing)
 		affine_scale.x = FixedMul(affine_scale.x, FixedMul(spritexscale, this_scale));
 		affine_scale.y = FixedMul(affine_scale.y, FixedMul(spriteyscale, this_scale));
 
+		affine_mosaic.x = FIXED_TO_FLOAT(FixedMul(affine_distscale.x, this_scale));
+		affine_mosaic.y = FIXED_TO_FLOAT(FixedMul(affine_distscale.y, this_scale));
+
 		angle_t angle;
 
 		INT32 flipsign = ((flip) ? -1 : 1);
@@ -2940,6 +2947,9 @@ static void R_ProjectSprite(mobj_t *thing)
 		vis->affine.transform.ox = affine_transform.ox;
 		vis->affine.transform.oy = affine_transform.oy;
 
+		vis->affine.mosaic.x = affine_mosaic.x;
+		vis->affine.mosaic.y = affine_mosaic.y;
+
 		R_CopyAffineBounds(&affine_bounds, &vis->affine.bounds);
 	}
 

src/r_things.h

@@ -220,6 +220,7 @@ struct vissprite_t
 		vector2_t scaling; // Affine scaling
 		vector2_t distscale; // X/Y scale based on camera distance
 		vector2_t offset; // Per-pixel offset
+		f_vector2_t mosaic; // Truncates how columndrawers "move" across the screen
 		angle_t rollangle; // Affine rotation angle
 		affine_t transform; // The actual affine transformation.
 		affine_bounding_t bounds; // The "bounding box" (draw area) of the affine sprite.

src/typedef.h

@@ -232,6 +232,7 @@ TYPEDEF (mdllistitem_t);
 
 // m_fixed.h
 TYPEDEF (vector2_t);
+TYPEDEF (f_vector2_t);
 TYPEDEF (vector3_t);
 TYPEDEF (vector4_t);
 TYPEDEF (matrix_t);