From 0e948660ff8c4ade59baf134bc754e02c2a08524 Mon Sep 17 00:00:00 2001
From: tovjemam <zbyvaj@seznam.cz>
Date: Thu, 14 Aug 2025 22:23:18 +0200
Subject: [PATCH] Fix portal disappearance when teleporting

---
 src/game/entity.cpp  |  1 +
 src/gfx/renderer.cpp | 44 +++++++++++++++++++++++++++++---------------
 src/gfx/renderer.hpp |  2 +-
 3 files changed, 31 insertions(+), 16 deletions(-)

diff --git a/src/game/entity.cpp b/src/game/entity.cpp
index 2973ba2..6a16b00 100644
--- a/src/game/entity.cpp
+++ b/src/game/entity.cpp
@@ -100,6 +100,7 @@ void game::Entity::Move(glm::vec3& velocity, float dt)
 			if (sd < 0.0f)
 			{
 				std::swap(occu_, other_occu_); // Swap occurrences
+				touching_portal_ = touching_portal_->link; // Switch to the linked portal
 			}
 		}
 
diff --git a/src/gfx/renderer.cpp b/src/gfx/renderer.cpp
index 36974d6..a66b9f9 100644
--- a/src/gfx/renderer.cpp
+++ b/src/gfx/renderer.cpp
@@ -172,8 +172,34 @@ void gfx::Renderer::DrawPortal(const DrawSectorParams& params, const game::Porta
 		return; // Eye is behind the portal plane, skip
 	}
 
+	const game::Portal& other_portal = *portal.link;
+
+	glm::mat4 portal_mesh_trans = portal.trans;
+	glm::vec4 new_clip_plane = other_portal.plane;
+	glm::vec3 portal_verts[4] = {
+		portal.verts[0],
+		portal.verts[1],
+		portal.verts[2],
+		portal.verts[3]
+	};
+
+	if (eye_plane_sd < min_portal_distance_)
+	{
+		float how_much_shift = min_portal_distance_ - eye_plane_sd;
+
+		portal_mesh_trans = glm::translate(portal_mesh_trans,
+			glm::vec3(0.0f, how_much_shift, 0.0f)); // Shift portal mesh to avoid clipping
+
+		new_clip_plane.w += how_much_shift; // Shift the clip plane as well
+
+		for (size_t i = 0; i < 4; ++i)
+		{
+			portal_verts[i] -= glm::vec3(portal.plane) * how_much_shift; // Shift portal vertices
+		}
+	}
+
 	collision::AABB2 portal_aabb;
-	if (!ComputePortalScreenAABB(portal, params.view_proj, portal_aabb))
+	if (!ComputeQuadScreenAABB(portal_verts, params.view_proj, portal_aabb))
 	{
 		return; // Portal is fully behind the camera, skip
 	}
@@ -183,21 +209,9 @@ void gfx::Renderer::DrawPortal(const DrawSectorParams& params, const game::Porta
 		return; // Portal AABB does not intersect with the screen AABB, skip
 	}
 
-	const game::Portal& other_portal = *portal.link;
 	const game::Sector& other_sector = *other_portal.sector;
 
-	glm::mat4 portal_mesh_trans = portal.trans;
-	glm::vec4 new_clip_plane = other_portal.plane;
 
-	if (eye_plane_sd < min_portal_distance_)
-	{
-		float how_much_shift = min_portal_distance_ - eye_plane_sd;
-
-		portal_mesh_trans = glm::translate(portal_mesh_trans, 
-			glm::vec3(0.0f, how_much_shift, 0.0f)); // Shift portal mesh to avoid clipping
-
-		new_clip_plane.w += how_much_shift; // Shift the clip plane as well
-	}
 
 
 	// Open portal
@@ -236,14 +250,14 @@ void gfx::Renderer::DrawPortal(const DrawSectorParams& params, const game::Porta
 	glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 }
 
-bool gfx::Renderer::ComputePortalScreenAABB(const game::Portal& portal, const glm::mat4 view_proj, collision::AABB2& aabb)
+bool gfx::Renderer::ComputeQuadScreenAABB(const glm::vec3* verts, const glm::mat4 view_proj, collision::AABB2& aabb)
 {
 	size_t num_behind = 0;
 
 	glm::vec4 clip[4];
 	for (size_t i = 0; i < 4; ++i)
 	{
-		glm::vec4 vert = glm::vec4(portal.verts[i], 1.0f);
+		glm::vec4 vert = glm::vec4(verts[i], 1.0f);
 		clip[i] = view_proj * vert;
 		
 		if (clip[i].w <= 0.0f)
diff --git a/src/gfx/renderer.hpp b/src/gfx/renderer.hpp
index 97582c8..5c13b2b 100644
--- a/src/gfx/renderer.hpp
+++ b/src/gfx/renderer.hpp
@@ -53,7 +53,7 @@ namespace gfx
 		void DrawSector(const DrawSectorParams& params);
 		void DrawPortal(const DrawSectorParams& params, const game::Portal& portal);
 		
-		static bool ComputePortalScreenAABB(const game::Portal& portal, const glm::mat4 view_proj, collision::AABB2& aabb);
+		static bool ComputeQuadScreenAABB(const glm::vec3* verts, const glm::mat4 view_proj, collision::AABB2& aabb);
 		void DrawPortalPlane(const DrawSectorParams& params, const game::Portal& portal, const glm::mat4& trans, bool clear_depth);
 	};