TexturedLineRData.h

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/* Copyright (C) 2023 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_TEXTUREDLINERDATA
#define INCLUDED_TEXTUREDLINERDATA

#include "graphics/Overlay.h"
#include "graphics/RenderableObject.h"
#include "graphics/ShaderProgram.h"
#include "graphics/TextureManager.h"
#include "maths/BoundingBoxAligned.h"
#include "renderer/backend/IDeviceCommandContext.h"
#include "renderer/backend/IShaderProgram.h"
#include "renderer/VertexBufferManager.h"

class CFrustum;

/**
 * Rendering data for an STexturedOverlayLine.
 *
 * Note that instances may be shared amongst multiple copies of the same STexturedOverlayLine instance.
 * The reason is that this rendering data is non-copyable, but we do wish to maintain copyability of
 * SOverlayTexturedLineData to not limit its usage patterns too much (particularly the practice of storing
 * them into containers).
 *
 * For this reason, instead of storing a reverse pointer back to any single SOverlayTexturedLine, the methods
 * in this class accept references to STexturedOverlayLines to work with. It is up to client code to pass in
 * SOverlayTexturedLines to all methods that are consistently the same instance or non-modified copies of it.
 */
class CTexturedLineRData : public CRenderData
{
    // we hold raw pointers to vertex buffer chunks that are handed out by the vertex buffer manager
    // and can not be safely duplicated by us.
    NONCOPYABLE(CTexturedLineRData);

public:
    CTexturedLineRData() = default;
    ~CTexturedLineRData() = default;

    static Renderer::Backend::IVertexInputLayout* GetVertexInputLayout();

    void Update(const SOverlayTexturedLine& line);
    void Render(Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        Renderer::Backend::IVertexInputLayout* vertexInputLayout,
        const SOverlayTexturedLine& line, Renderer::Backend::IShaderProgram* shader);

    bool IsVisibleInFrustum(const CFrustum& frustum) const;

protected:

    struct SVertex
    {
        SVertex(const CVector3D& pos, const CVector2D& uv) : m_Position(pos), m_UV(uv) { }
        CVector3D m_Position;
        CVector2D m_UV;
        float padding[3]; // get a pow2 struct size
    };
    cassert(sizeof(SVertex) == 32);

    /**
     * Creates a line cap of the specified type @p endCapType at the end of the segment going in direction @p normal, and appends
     * the vertices to @p verticesOut in GL_TRIANGLES order.
     *
     * @param corner1 One of the two butt-end corner points of the line to which the cap should be attached.
     * @param corner2 One of the two butt-end corner points of the line to which the cap should be attached.
     * @param normal Normal vector indicating the direction of the segment to which the cap should be attached.
     * @param endCapType The type of end cap to produce.
     * @param verticesOut Output vector of vertices for passing to the renderer.
     * @param indicesOut Output vector of vertex indices for passing to the renderer.
     */
    void CreateLineCap(const SOverlayTexturedLine& line, const CVector3D& corner1, const CVector3D& corner2, const CVector3D& normal,
                       SOverlayTexturedLine::LineCapType endCapType, std::vector<SVertex>& verticesOut, std::vector<u16>& indicesOut);

    /// Small utility function; grabs the centroid of the positions of two vertices
    inline CVector3D Centroid(const SVertex& v1, const SVertex& v2)
    {
        return (v1.m_Position + v2.m_Position) * 0.5;
    }

    CVertexBufferManager::Handle m_VB;
    CVertexBufferManager::Handle m_VBIndices;
    CBoundingBoxAligned m_BoundingBox;
};

#endif // INCLUDED_TEXTUREDLINERDATA