glviewer.h

/*
 * GLViewer is a simple interface for opengl by handling the GLCore library 
 * 
 */
#pragma once

#include "glviewer_common.h"
#include "buffers.h"
  
namespace GLViewer {

/*
        
TODO: 

    Viewer Dynamic GeometryBuffer:
        The raw value Viewer needs is a Vertex (glm::vec3 position; glm::vec3 colour; )
        currently we are using a Vertices (std::vector<glm::vec3> positions; glm::vec3 colour; )
        We want to tell the dynamic buffer, this is where the data is.. e.g:
        - allow a custom vector as a parameter like imgui does
        - AddVertexPtr() Callback function to show where the point is to render and how to render it. emplace_back(glm::vec3 pos, glm::vec3 colour)
        - maybe a template so you can pass anything?


// TODO: Callback to create vertices directly in place, also needs colour  

*/ 

class Viewer
{
public:
    Viewer();

    Camera_CentreObject     camera;
    Buffers                 buffers;

    float ScaleToPx(float size) { return size * (camera.GetZoom() / Window::GetHeight()); } 
    glm::vec2 ScaleToPx(const glm::vec2& p) { return  { ScaleToPx(p.x), ScaleToPx(p.y) }; } 
    
    glm::vec3 ScreenToWorldCoords(const glm::vec2& p, bool invertY = true) 
    {
        glm::vec2 screenCoords = invertY ? Window::InvertYCoord(p) : p;// + glm::vec2(0.0f, 1.0f); // TODO DO WE NEED TO OFFSET ???
        return camera.GetWorldPosition(screenCoords);      
    };

    std::optional<glm::vec2> WorldToScreenCoords(const glm::vec3& p, bool invertY = true) {
        
        auto [success, position] = camera.GetScreenCoords(glm::vec3({ p.x, p.y, p.z }));
        
        if (!success) { return std::nullopt; }
        
        return std::optional<glm::vec2>{ invertY ? Window::InvertYCoord(position) : position };
    };

    void Render();
    void RenderLoop(GLSystem& glsys, std::function<void()> cb_Configure, std::function<void()> cb_Draw_ImGui, std::function<void()> cb_Set_DynamicBuffers, std::function<void()> cb_Finalise = nullptr);

private:
    
    // Projection / View matrices
    glm::mat4 m_Proj;
    glm::mat4 m_View;
};
} // End namespace GLViewer