From 298f6c7015ad1151bd02c182c9cf3f47790c3f53 Mon Sep 17 00:00:00 2001
From: past-due <30942300+past-due@users.noreply.github.com>
Date: Sun, 17 Mar 2024 14:54:50 -0400
Subject: [PATCH] renderFeature: Stretch tree foundation if needed

---
 src/display3d.cpp | 14 +++++++++++++-
 src/feature.cpp   | 16 ++++++----------
 src/featuredef.h  |  1 +
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/src/display3d.cpp b/src/display3d.cpp
index 680be0dfb95..9cbe9361dd4 100644
--- a/src/display3d.cpp
+++ b/src/display3d.cpp
@@ -2479,12 +2479,24 @@ void	renderFeature(FEATURE *psFeature, const glm::mat4 &viewMatrix, const glm::m
 		/* these cast a shadow */
 		pieFlags = pie_SHADOW;
 	}
+
 	iIMDBaseShape *imd = psFeature->sDisplay.imd;
 	if (imd)
 	{
+		iIMDShape *strImd = imd->displayModel();
+
+		float stretchDepth = 0.f;
+		if (!(strImd->flags & iV_IMD_NOSTRETCH))
+		{
+			if (psFeature->psStats->subType == FEAT_TREE) // for now, only do this for trees
+			{
+				stretchDepth = psFeature->pos.z - psFeature->foundationDepth;
+			}
+		}
+
 		/* Translate the feature  - N.B. We can also do rotations here should we require
 		buildings to face different ways - Don't know if this is necessary - should be IMO */
-		pie_Draw3DShape(imd->displayModel(), 0, 0, brightness, pieFlags, 0, modelMatrix, viewMatrix);
+		pie_Draw3DShape(strImd, 0, 0, brightness, pieFlags, 0, modelMatrix, viewMatrix, stretchDepth);
 	}
 
 	setScreenDispWithPerspective(&psFeature->sDisplay, perspectiveViewMatrix * modelMatrix);
diff --git a/src/feature.cpp b/src/feature.cpp
index 58f748a5e4f..0653a17a739 100644
--- a/src/feature.cpp
+++ b/src/feature.cpp
@@ -202,16 +202,11 @@ static void updateFeatureOrientation(FEATURE *psFeature)
 	psFeature->pos.z = MAX(psFeature->pos.z, (hx0 + hx1) / 2);
 	psFeature->pos.z = MAX(psFeature->pos.z, (hy0 + hy1) / 2);
 
-	if (psFeature->psStats->subType == FEAT_TREE)
+	if (psFeature->psStats->subType == FEAT_TREE ||
+		psFeature->psStats->subType == FEAT_SKYSCRAPER ||
+		psFeature->psStats->subType == FEAT_BUILDING)
 	{
-		// Do not rotate or pitch - trees look weird if they aren't pointing up
-		// FUTURE TODO: Ensure that no tree geometry is hovering above the terrain when placed on an aggressive slope, while still ensuring it points up, by burying the base a bit if needed?
-		return;
-	}
-	if (psFeature->psStats->subType == FEAT_SKYSCRAPER)
-	{
-		// Do not rotate or pitch - skyscrapers should also point up
-		// FUTURE TODO: Possibly stretch the base of the skyscraper if needed?
+		// Do not rotate or pitch - trees + buildings look weird if they aren't pointing up
 		return;
 	}
 
@@ -235,7 +230,6 @@ static void updateFeatureOrientation(FEATURE *psFeature)
 	psFeature->rot.roll = iAtan2(dzdw, (2 * d) << 16);		// pitch = atan(∂z(x, y)/∂w)/2π << 16
 }
 
-
 /* Create a feature on the map */
 FEATURE *buildFeature(FEATURE_STATS *psStats, UDWORD x, UDWORD y, bool FromSave, uint32_t id)
 {
@@ -296,6 +290,7 @@ FEATURE *buildFeature(FEATURE_STATS *psStats, UDWORD x, UDWORD y, bool FromSave,
 	psFeature->body = psStats->body;
 	psFeature->periodicalDamageStart = 0;
 	psFeature->periodicalDamage = 0;
+	psFeature->foundationDepth = std::min<float>(foundationMin, TILE_MAX_HEIGHT);
 
 	// it has never been drawn
 	psFeature->sDisplay.frameNumber = 0;
@@ -361,6 +356,7 @@ FEATURE *buildFeature(FEATURE_STATS *psStats, UDWORD x, UDWORD y, bool FromSave,
 FEATURE::FEATURE(uint32_t id, FEATURE_STATS const *psStats)
 	: BASE_OBJECT(OBJ_FEATURE, id, PLAYER_FEATURE)  // Set the default player out of range to avoid targeting confusions
 	, psStats(psStats)
+	, foundationDepth(0.f)
 {}
 
 /* Release the resources associated with a feature */
diff --git a/src/featuredef.h b/src/featuredef.h
index 55bfc2bfd27..58e54a88bfb 100644
--- a/src/featuredef.h
+++ b/src/featuredef.h
@@ -70,6 +70,7 @@ struct FEATURE : public BASE_OBJECT
 	~FEATURE();
 
 	FEATURE_STATS const *psStats;
+	float foundationDepth;           ///< Depth of features's foundation		// DISPLAY-ONLY
 
 	inline Vector2i size() const { return psStats->size(); }
 };