Billboard foliage

Partition the instances by within/without the view frustum, then by
proximity to the view point and within/without the sunlight shadow
frustum. Use billboards for far away/out of view instances.

2 files changed, 83 insertions, 14 deletions

diff --git a/game/scenary/foliage.cpp b/game/scenary/foliage.cpp
index 140c4e5..6b471fc 100644
--- a/game/scenary/foliage.cpp
+++ b/game/scenary/foliage.cpp
@@ -1,4 +1,5 @@
 #include "foliage.h"
+#include "gfx/frustum.h"
 #include "gfx/gl/sceneShader.h"
 #include "gfx/gl/shadowMapper.h"
 #include "gfx/gl/vertexArrayObject.h"
@@ -33,33 +34,94 @@ Foliage::postLoad()
 void
 Foliage::updateStencil(const ShadowStenciller & ss) const
 {
-	if (instances.size() > 0) {
+	if (instancePartitions.second.second != instancePartitions.second.first) {
 		ss.renderStencil(shadowStencil, *bodyMesh, texture);
 	}
 }
 
 void
+Foliage::updateBillboard(const BillboardPainter & bbp) const
+{
+	if (instancePartitions.first != instancePartitions.second.first) {
+		bbp.renderBillBoard(billboard, *bodyMesh, texture);
+	}
+}
+
+void
+Foliage::preFrame(const Frustum & frustum, const Frustum & lighting)
+{
+	if (instances.size() > 0) {
+		const auto dims = bodyMesh->getDimensions();
+		instancePartitions = instances.partition(
+				[&frustum, &dims](const auto & location) {
+					return frustum.contains(location.position + dims.centre, dims.size);
+				},
+				[&frustum](const auto & location) {
+					return distance(frustum.getPosition(), location.position) < 140'000.F;
+				},
+				[&lighting, &dims](const auto & location) {
+					return lighting.contains(location.position + dims.centre, dims.size);
+				});
+		//         In view frustum       /            Outside view frustum            /
+		// Close to view / Far from view / Casts shadow into view / No shadow in view /
+	}
+}
+
+void
 Foliage::render(const SceneShader & shader, const Frustum &) const
 {
-	if (const auto count = instances.size()) {
-		shader.basicInst.use();
-		if (texture) {
-			texture->bind();
+	if (instancePartitions.first) {
+		glDebugScope _ {instancePointVAO};
+		std::ignore = instances.size();
+		if (const auto count = instancePartitions.first - instancePartitions.second.first) {
+			glDebugScope _ {0, "Billboard"};
+			const auto dimensions = bodyMesh->getDimensions();
+			shader.billboard.use(dimensions.size, dimensions.centre);
+			glActiveTexture(GL_TEXTURE0);
+			glBindTexture(GL_TEXTURE_2D_ARRAY, billboard[0]);
+			glActiveTexture(GL_TEXTURE1);
+			glBindTexture(GL_TEXTURE_2D_ARRAY, billboard[1]);
+			glActiveTexture(GL_TEXTURE2);
+			glBindTexture(GL_TEXTURE_2D_ARRAY, billboard[2]);
+			glBindVertexArray(instancePointVAO);
+			glDrawArrays(GL_POINTS, static_cast<GLint>(instancePartitions.second.first), static_cast<GLsizei>(count));
+			glBindVertexArray(0);
+		}
+		if (const auto count = instancePartitions.second.first) {
+			glDebugScope _ {0, "Mesh"};
+			shader.basicInst.use();
+			if (texture) {
+				texture->bind();
+			}
+			bodyMesh->DrawInstanced(instanceVAO, static_cast<GLsizei>(count));
 		}
-		bodyMesh->DrawInstanced(instanceVAO, static_cast<GLsizei>(count));
 	}
 }
 
 void
 Foliage::shadows(const ShadowMapper & mapper, const Frustum &) const
 {
-	if (const auto count = instances.size()) {
-		const auto dimensions = bodyMesh->getDimensions();
-		mapper.stencilShadowProgram.use(dimensions.centre, dimensions.size);
-		glActiveTexture(GL_TEXTURE0);
-		glBindTexture(GL_TEXTURE_2D_ARRAY, shadowStencil);
-		glBindVertexArray(instancePointVAO);
-		glDrawArrays(GL_POINTS, 0, static_cast<GLsizei>(count));
-		glBindVertexArray(0);
+	if (instancePartitions.second.second) {
+		glDebugScope _ {instancePointVAO};
+		std::ignore = instances.size();
+		if (const auto count = instancePartitions.second.second - instancePartitions.second.first) {
+			const auto dimensions = bodyMesh->getDimensions();
+			mapper.stencilShadowProgram.use(dimensions.centre, dimensions.size);
+			glActiveTexture(GL_TEXTURE0);
+			glBindTexture(GL_TEXTURE_2D_ARRAY, shadowStencil);
+			glBindVertexArray(instancePointVAO);
+			glDrawArrays(GL_POINTS, static_cast<GLint>(instancePartitions.second.first), static_cast<GLsizei>(count));
+			glBindVertexArray(0);
+		}
+		if (const auto count = instancePartitions.second.first) {
+			if (texture) {
+				texture->bind(GL_TEXTURE3);
+				mapper.dynamicPointInstWithTextures.use();
+			}
+			else {
+				mapper.dynamicPointInst.use();
+			}
+			bodyMesh->DrawInstanced(instanceVAO, static_cast<GLsizei>(count));
+		}
 	}
 }
diff --git a/game/scenary/foliage.h b/game/scenary/foliage.h
index d15a8b0..61bdb5b 100644
--- a/game/scenary/foliage.h
+++ b/game/scenary/foliage.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "assetFactory/asset.h"
+#include "gfx/gl/billboardPainter.h"
 #include "gfx/gl/instanceVertices.h"
 #include "gfx/gl/shadowStenciller.h"
 #include "gfx/models/texture.h"
@@ -26,13 +27,19 @@ public:
 	};
 
 	mutable InstanceVertices<LocationVertex> instances;
+	void preFrame(const Frustum &, const Frustum &) override;
 	void render(const SceneShader &, const Frustum &) const override;
 	void shadows(const ShadowMapper &, const Frustum &) const override;
 	void updateStencil(const ShadowStenciller &) const override;
+	void updateBillboard(const BillboardPainter &) const override;
 	glTexture shadowStencil = ShadowStenciller::createStencilTexture(256, 256);
+	glTextures<3> billboard = BillboardPainter::createBillBoardTextures(256, 256);
 
 protected:
 	friend Persistence::SelectionPtrBase<std::shared_ptr<Foliage>>;
 	bool persist(Persistence::PersistenceStore & store) override;
 	void postLoad() override;
+
+private:
+	InstanceVertices<Foliage::LocationVertex>::PartitionResult instancePartitions;
 };