From 7aceefa90456e800aea1c3d0916b85da9084d670 Mon Sep 17 00:00:00 2001
From: Nep2Disk <suesakamoto@outlook.com>
Date: Tue, 16 Sep 2025 01:59:15 +0000
Subject: [PATCH] Add support for terrain floorClip and RF_ALWAYSONTOP in
 legacyGL

---
 src/hardware/hw_main.c | 18 +++++++++++++++++-
 src/hardware/hw_md2.c  |  4 +++-
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index 085769040..232082bbc 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -3415,6 +3415,11 @@ static void HWR_SplitSprite(gl_vissprite_t *spr)
 			return; // cap
 
 		blend = HWR_SurfaceBlend(blendmode, trans, &Surf);
+
+		// if sprite has PF_ALWAYSONTOP, draw on top of everything.
+		if (cv_debugrender_spriteclip.value || spr->mobj->renderflags & RF_ALWAYSONTOP)
+			blend |= PF_NoDepthTest;
+
 		if (!trans && !blendmode)
 		{
 			// BP: i agree that is little better in environement but it don't
@@ -3896,6 +3901,11 @@ static void HWR_DrawSprite(gl_vissprite_t *spr)
 				return; // cap
 
 			blend = HWR_SurfaceBlend(blendmode, trans, &Surf);
+
+			// if sprite has PF_ALWAYSONTOP, draw on top of everything.
+			if (cv_debugrender_spriteclip.value || spr->mobj->renderflags & RF_ALWAYSONTOP)
+				blend |= PF_NoDepthTest;
+
 			if (!trans && !blendmode)
 			{
 				// BP: i agree that is little better in environement but it don't
@@ -3921,7 +3931,10 @@ static void HWR_DrawSprite(gl_vissprite_t *spr)
 
 		if (HWR_UseShader())
 		{
-			shader = (R_ThingIsPaperSprite(spr->mobj) || R_ThingIsFloorSprite(spr->mobj)) ? SHADER_SPRITE : SHADER_SPRITECLIPHACK;;
+			shader = (R_ThingIsPaperSprite(spr->mobj)
+				|| R_ThingIsFloorSprite(spr->mobj)
+				|| (spr->mobj->terrain && spr->mobj->terrain->floorClip)
+				) ? SHADER_SPRITE : SHADER_SPRITECLIPHACK;
 			blend |= PF_ColorMapped;
 		}
 
@@ -5007,6 +5020,9 @@ static void HWR_ProjectSprite(mobj_t *thing)
 		x1 = tr_x + x1 * rightcos;
 		x2 = tr_x - x2 * rightcos;
 
+		if (thing->terrain && thing->terrain->floorClip)
+			spr_topoffset -=  thing->terrain->floorClip;
+
 		if (vflip)
 		{
 			gz = FIXED_TO_FLOAT(interp.z + thing->height) - (FIXED_TO_FLOAT(spr_topoffset) * this_yscale);
diff --git a/src/hardware/hw_md2.c b/src/hardware/hw_md2.c
index 01b42140a..81a7d9a49 100644
--- a/src/hardware/hw_md2.c
+++ b/src/hardware/hw_md2.c
@@ -1723,6 +1723,8 @@ boolean HWR_DrawModel(gl_vissprite_t *spr)
 		HWD.pfnSetShader(SHADER_MODEL);	// model shader
 		{
 			float this_scale = FIXED_TO_FLOAT(spr->mobj->scale);
+			fixed_t floorClip = spr->mobj->terrain ? spr->mobj->terrain->floorClip : 0;
+			float finalfloorClip = FIXED_TO_FLOAT(FixedMul(floorClip, mapobjectscale)*P_MobjFlip(spr->mobj));
 
 			float xs = this_scale * FIXED_TO_FLOAT(spr->mobj->spritexscale);
 			float ys = this_scale * FIXED_TO_FLOAT(spr->mobj->spriteyscale);
@@ -1733,7 +1735,7 @@ boolean HWR_DrawModel(gl_vissprite_t *spr)
 			// offset perpendicular to the camera angle
 			p.x -= ox * gl_viewsin;
 			p.y += ox * gl_viewcos;
-			p.z += oy;
+			p.z += oy - finalfloorClip;
 
 			if (R_ThingIsUsingBakedOffsets(spr->mobj))
 			{