Shadow mapping render pass (#11244)

Co-authored-by: x2048 <codeforsmile@gmail.com>

src/client/shadows/dynamicshadows.h

@@ -0,0 +1,102 @@
+/*
+Minetest
+Copyright (C) 2021 Liso <anlismon@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+
+#include "irrlichttypes_bloated.h"
+#include <matrix4.h>
+#include "util/basic_macros.h"
+
+class Camera;
+class Client;
+
+struct shadowFrustum
+{
+	float zNear{0.0f};
+	float zFar{0.0f};
+	float length{0.0f};
+	core::matrix4 ProjOrthMat;
+	core::matrix4 ViewMat;
+	v3f position;
+};
+
+class DirectionalLight
+{
+public:
+	DirectionalLight(const u32 shadowMapResolution,
+			const v3f &position,
+			video::SColorf lightColor = video::SColor(0xffffffff),
+			f32 farValue = 100.0f);
+	~DirectionalLight() = default;
+
+	//DISABLE_CLASS_COPY(DirectionalLight)
+
+	void update_frustum(const Camera *cam, Client *client);
+
+	// when set direction is updated to negative normalized(direction)
+	void setDirection(v3f dir);
+	v3f getDirection() const{
+		return direction;
+	};
+	v3f getPosition() const;
+
+	/// Gets the light's matrices.
+	const core::matrix4 &getViewMatrix() const;
+	const core::matrix4 &getProjectionMatrix() const;
+	core::matrix4 getViewProjMatrix();
+
+	/// Gets the light's far value.
+	f32 getMaxFarValue() const
+	{
+		return farPlane;
+	}
+
+
+	/// Gets the light's color.
+	const video::SColorf &getLightColor() const
+	{
+		return diffuseColor;
+	}
+
+	/// Sets the light's color.
+	void setLightColor(const video::SColorf &lightColor)
+	{
+		diffuseColor = lightColor;
+	}
+
+	/// Gets the shadow map resolution for this light.
+	u32 getMapResolution() const
+	{
+		return mapRes;
+	}
+
+	bool should_update_map_shadow{true};
+
+private:
+	void createSplitMatrices(const Camera *cam);
+
+	video::SColorf diffuseColor;
+
+	f32 farPlane;
+	u32 mapRes;
+
+	v3f pos;
+	v3f direction{0};
+	shadowFrustum shadow_frustum;
+};