From 12d7acf095f885a97166ca16c6d274817ab342f7 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 8 Mar 2025 00:59:23 +0000
Subject: Current tile in frustum as we loop

Chunk by surface only, render if visible in frustum
---
 game/terrain.cpp      | 14 +++++---------
 game/terrain.h        |  1 -
 test/Jamfile.jam      |  3 ++-
 test/perf-terrain.cpp | 17 +++++++++++++++++
 4 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/game/terrain.cpp b/game/terrain.cpp
index dae295a..530b373 100644
--- a/game/terrain.cpp
+++ b/game/terrain.cpp
@@ -111,21 +111,17 @@ Terrain::render(const SceneShader & shader, const Frustum & frustum) const
 {
 	grass->bind();
 
-	std::ranges::for_each(meshes, [ext = getExtents(), &frustum](const auto & surfaceDef) {
-		surfaceDef.second.visible = frustum.contains(surfaceDef.second.aabb);
-	});
-
 	const auto chunkBySurface = std::views::chunk_by([](const auto & itr1, const auto & itr2) {
 		return itr1.first.surface == itr2.first.surface;
 	});
-	for (const auto & surfaceRange : meshes | std::views::filter([](const auto & itr) {
-			 return itr.second.visible;
-		 }) | chunkBySurface) {
+	for (const auto & surfaceRange : meshes | chunkBySurface) {
 		const auto surface = surfaceRange.front().first.surface;
 		shader.landmass.use(surface ? surface->colorBias : OPEN_SURFACE);
 		for (const auto & sab : surfaceRange) {
-			glBindVertexArray(sab.second.vertexArray);
-			glDrawElements(GL_TRIANGLES, sab.second.count, GL_UNSIGNED_INT, nullptr);
+			if (frustum.contains(sab.second.aabb)) {
+				glBindVertexArray(sab.second.vertexArray);
+				glDrawElements(GL_TRIANGLES, sab.second.count, GL_UNSIGNED_INT, nullptr);
+			}
 		}
 	}
 	glBindVertexArray(0);
diff --git a/game/terrain.h b/game/terrain.h
index 1d00f97..f38fe84 100644
--- a/game/terrain.h
+++ b/game/terrain.h
@@ -36,7 +36,6 @@ private:
 		glBuffer indicesBuffer;
 		GLsizei count;
 		AxisAlignedBoundingBox aabb;
-		mutable bool visible;
 	};
 
 	struct SurfaceKey {
diff --git a/test/Jamfile.jam b/test/Jamfile.jam
index 8219398..bedc2ad 100644
--- a/test/Jamfile.jam
+++ b/test/Jamfile.jam
@@ -71,5 +71,6 @@ explicit perf-assetFactory ;
 explicit perf-persistence ;
 explicit perf-geoData ;
 explicit perf-instancing ;
-alias perf : perf-assetFactory perf-persistence perf-geoData perf-instancing ;
+explicit perf-terrain ;
+alias perf : perf-assetFactory perf-persistence perf-geoData perf-instancing perf-terrain ;
 explicit perf ;
diff --git a/test/perf-terrain.cpp b/test/perf-terrain.cpp
index 81cb16c..e75f80b 100644
--- a/test/perf-terrain.cpp
+++ b/test/perf-terrain.cpp
@@ -1,4 +1,7 @@
 #include "game/terrain.h"
+#include "gfx/camera.h"
+#include "gfx/frustum.h"
+#include "gfx/gl/sceneShader.h"
 #include "testMainWindow.h"
 #include <benchmark/benchmark.h>
 
@@ -14,8 +17,22 @@ namespace {
 			terrain.generateMeshes();
 		}
 	}
+
+	void
+	terrainRender(benchmark::State & state)
+	{
+		Terrain terrain {GeoData::loadFromAsciiGrid(FIXTURESDIR "height/SD19.asc")};
+		SceneShader shader;
+		Camera cam {terrain.getExtents().min + GlobalPosition3D {0, 0, 10000}, 45.F, 1.F, 1, 10000};
+		cam.setForward(::north + ::east);
+
+		for (auto _ : state) {
+			terrain.render(shader, cam);
+		}
+	}
 }
 
 BENCHMARK(terrainMeshgen);
+BENCHMARK(terrainRender);
 
 BENCHMARK_MAIN();
-- 
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