TSE/TSE_Core/src/BehaviourScripts/Camera.cpp

#include "Camera.hpp"
#include "elements/Transformable.hpp"
#include "interfaces/IRenderer.hpp"

TSE::Camera* TSE::Camera::mainCamera = nullptr;
TSE::ICameraHelper* TSE::Camera::helper = nullptr;

float TSE::Camera::GetRenderScale() const
{
    return RenderScale;
}

TSE::ProjectionType TSE::Camera::GetProjection() const
{
    return projection;
}

float TSE::Camera::GetNearClippingPlane() const
{
    return nearClippingPlane;
}

float TSE::Camera::GetFarClippingPlane() const
{
    return farClippingPlane;
}

float TSE::Camera::GetFov() const
{
    return fov;
}

TSE::Vector3 TSE::Camera::SceenPositionToGamePosition(Vector2 screenPos)
{
    float x = 2.0f * screenPos.x / lastRtSize.x -1.0f;
    float y = 1.0f - 2.0f * screenPos.y / lastRtSize.y;
    float z = -1.0f;
    Vector4 ndc(x,y,x,1);

    Matrix4x4 InversProj = Matrix4x4(*projectionMatrix);
    InversProj.Invert();
    Vector4 camSpace = InversProj * ndc;
    camSpace = camSpace / camSpace.w;
    Vector3 relativPos(camSpace);
    relativPos.z = 0;
    return baseObject->LocalToGlobalPosition(relativPos);
}

void TSE::Camera::SetRenderScale(float v)
{
    RenderScale = v; RecalculateProjMatrix();
}

void TSE::Camera::SetProjection(ProjectionType v)
{
    projection = v; RecalculateProjMatrix();
}

void TSE::Camera::SetNearClippingPlane(float v)
{
    nearClippingPlane = v; RecalculateProjMatrix();
}

void TSE::Camera::SetFarClippingPlane(float v)
{
    farClippingPlane = v; RecalculateProjMatrix(); 
}

void TSE::Camera::SetFov(float v)
{
    fov = v; RecalculateProjMatrix();
}

TSE::Camera::Camera()
{
}

TSE::Camera::~Camera()
{
    delete(projectionMatrix);
    if(mainCamera == this)
        mainCamera = nullptr;
}

void TSE::Camera::OnResize(float width, float height, IResizable *wnd)
{
    lastRtSize = {width, height};
    RecalculateProjMatrix();
}

void TSE::Camera::SetRenderTarget(IRenderTarget *target)
{
    if(rt != nullptr)
        rt->RemoveResizeNotifiable(this);
    if(target != nullptr)
        target->AddResizeNotifiable(this);
    rt = target;
    RecalculateProjMatrix();
}

TSE::IRenderTarget *TSE::Camera::GetRenderTarget()
{
    return rt;
}

void TSE::Camera::RecalculateProjMatrix()
{
    if(projectionMatrix)
        delete(projectionMatrix);

    if(projection == ProjectionType::Orthographic)
    {
        float x = lastRtSize.x / RenderScale;
        float y = lastRtSize.y / RenderScale;
        float mx = -x;
        float my = -y;
        projectionMatrix = new Matrix4x4(Matrix4x4::Orthographic(mx, x, my, y, nearClippingPlane, farClippingPlane));
    }
    else if(projection == ProjectionType::Perspective)
    {
        float x = lastRtSize.x / RenderScale;
        float y = lastRtSize.y / RenderScale;

        float aspectRatio = x / y;

        projectionMatrix = new Matrix4x4(Matrix4x4::Perspective(fov, aspectRatio, nearClippingPlane, farClippingPlane));
    }
}

void TSE::Camera::OnUpdate()
{
    if(mainCamera == nullptr && baseObject->name != ".EditorCamera")
    {
        mainCamera = this;
    }

    if(rt != nullptr)
        IRenderer::camerasToRenderWith.push_back(this);
}

void TSE::Camera::Start()
{
    if(mainCamera == nullptr && baseObject->name != ".EditorCamera")
    {
        mainCamera = this;
    }
}


TSE::Matrix4x4 BuildView_Zplus_RH(const TSE::Matrix4x4& world)
{
    using namespace TSE;
    // Welt-Position (w=1)
    Vector3 pos = Vector3(world * Vector4(0,0,0,1));

    // Richtungsachsen in Welt (w=0, KEINE Translation!)
    Vector3 fwdWS = Vector3(world * Vector4(0,0,1,0)); // +Z vorwärts in Welt
    Vector3 upWS  = Vector3(world * Vector4(0,1,0,0)); // +Y oben in Welt

    // Orthonormale Basis aufbauen (X+ soll "right" sein)
    Vector3 f = Vector3::Normalize(fwdWS);
    Vector3 r = Vector3::Normalize(Vector3::Cross(upWS, f)); // right = up × forward  => (+1,0,0) im Identity-Fall
    Vector3 u = Vector3::Cross(f, r);                        // re-orthonormalisiertes up

    Matrix4x4 view(1.0f); // Identität als Basis

    // Row-major befüllen (Zeilen = r,u,-f), letzte Spalte = -dot(row, pos) bzw. +dot(f,pos)
    view.m[0][0] = r.x;  view.m[0][1] = r.y;  view.m[0][2] = r.z;  view.m[0][3] = -Vector3::Dot(r, pos);
    view.m[1][0] = u.x;  view.m[1][1] = u.y;  view.m[1][2] = u.z;  view.m[1][3] = -Vector3::Dot(u, pos);
    view.m[2][0] = -f.x; view.m[2][1] = -f.y; view.m[2][2] = -f.z; view.m[2][3] =  Vector3::Dot(f, pos);
    view.m[3][0] = 0.0f; view.m[3][1] = 0.0f; view.m[3][2] = 0.0f; view.m[3][3] = 1.0f;

    return view;
}

void TSE::Camera::PreDraw(IShader *shader)
{
    rt->Bind();
    shader->SetUniform("prMatrix", projectionMatrix);
    
    auto worlmatrix = baseObject->GetGlobalMatrix();

    viewMatrix = BuildView_Zplus_RH(worlmatrix);

    shader->SetUniform("camMatrix", &viewMatrix);
    helper->OnRenderTargetChanged(lastRtSize.x, lastRtSize.y);
}

void TSE::Camera::PostDraw()
{
    rt->Unbind();
}

void TSE::Camera::Bind()
{
    rt->Bind();
}

void TSE::Camera::Unbind()
{
    rt->Unbind();
}

void TSE::Camera::UpdateRenderTarget()
{
    rt->Update();
}