2018-soft-3d-renderer/include/geometry.h

#ifndef GEOMETRY_H

#include "color.h"
#include "engine.h"
#include "point.h"
#include <cstdint>
#include <vector>


// STRUCTURES
struct Material
{
    ColorF32 kAmbient;
    ColorF32 kDiffuse;
};

struct Face
{
    unsigned int vertIndex[3];
    Vector normal;
    ColorF32 color;
};

struct Vertex
{
    Point point;
    Vector normal;
    ColorF32 color;
};

struct MeshRenderData
{
    std::vector<Vertex> vertsTransformed;
    std::vector<Face> culledFaces;
    bool smooth;
};

struct Mesh
{
    inline Mesh(void)
    {
        position.x = 0.0f;
        position.y = 0.0f;
        position.z = 0.0f;

        rotation[0] = 0.0f;
        rotation[1] = 0.0f;
        rotation[2] = 0.0f;

        scale = 1.0f;
    }

    inline void CullBackfaces(Point camPosition)
    {
        renderData.culledFaces.clear();

        for (size_t f = 0; f < faces.size(); ++f)
        {
            unsigned int v0 = faces[f].vertIndex[0];
            unsigned int v1 = faces[f].vertIndex[1];
            unsigned int v2 = faces[f].vertIndex[2];

            Vector v01 =
                renderData.vertsTransformed[v1].point
                - renderData.vertsTransformed[v0].point;

            Vector v02 =
                renderData.vertsTransformed[v2].point -
                renderData.vertsTransformed[v0].point;

            Vector normal = Vector::Cross(v01, v02);

            // Store normal for flat shading
            faces[f].normal = normal;
            faces[f].normal.Normalize();

            // Invert for Blender-compatibility
            normal = -normal;

            // Eye vector to viewport
            Vector view = camPosition - renderData.vertsTransformed[v0].point;

            float dot = Vector::Dot(normal, view);

            if (dot < EPSILON_E3)
            {
                renderData.culledFaces.push_back(faces[f]);
            }
        }
    }


    Point position;
    float rotation[3];
    float scale;

    std::vector<Vertex> verts;
    std::vector<Face> faces;
    Material material;

    MeshRenderData renderData;
};


// PUBLIC FUNCTIONS
void RenderMesh(
        Engine_Buffer &buffer, MeshRenderData &mesh);


#define GEOMETRY_H
#endif