bullet3/examples/TinyRenderer/TinyRenderer.cpp

#include "TinyRenderer.h"

#include <vector>
#include <limits>
#include <iostream>
#include "TinyRenderer/tgaimage.h"
#include "TinyRenderer/model.h"
#include "TinyRenderer/geometry.h"
#include "TinyRenderer/our_gl.h"
#include "../../Utils/b3ResourcePath.h"
#include "Bullet3Common/b3MinMax.h"

Vec3f light_dir_world(1,1,1);


struct Shader : public IShader {
    
    Model* m_model;
    Vec3f m_light_dir_local;
    Matrix& m_modelView;
    Matrix& m_projectionMatrix;
    
    mat<2,3,float> varying_uv;  // triangle uv coordinates, written by the vertex shader, read by the fragment shader
    mat<4,3,float> varying_tri; // triangle coordinates (clip coordinates), written by VS, read by FS
    mat<3,3,float> varying_nrm; // normal per vertex to be interpolated by FS
    mat<3,3,float> ndc_tri;     // triangle in normalized device coordinates

    Shader(Model* model, Vec3f light_dir_local, Matrix& modelView, Matrix& projectionMatrix)
    :m_model(model),
    m_light_dir_local(light_dir_local),
    m_modelView(modelView),
    m_projectionMatrix(projectionMatrix)
    {
        
    }
    
    virtual Vec4f vertex(int iface, int nthvert) {
        varying_uv.set_col(nthvert, m_model->uv(iface, nthvert));
        varying_nrm.set_col(nthvert, proj<3>((m_projectionMatrix*m_modelView).invert_transpose()*embed<4>(m_model->normal(iface, nthvert), 0.f)));
        Vec4f gl_Vertex = m_projectionMatrix*m_modelView*embed<4>(m_model->vert(iface, nthvert));
        varying_tri.set_col(nthvert, gl_Vertex);
        ndc_tri.set_col(nthvert, proj<3>(gl_Vertex/gl_Vertex[3]));
        return gl_Vertex;
    }

    virtual bool fragment(Vec3f bar, TGAColor &color) {
        Vec3f bn = (varying_nrm*bar).normalize();
        Vec2f uv = varying_uv*bar;

        mat<3,3,float> A;
        A[0] = ndc_tri.col(1) - ndc_tri.col(0);
        A[1] = ndc_tri.col(2) - ndc_tri.col(0);
        A[2] = bn;

        mat<3,3,float> AI = A.invert();

        Vec3f i = AI * Vec3f(varying_uv[0][1] - varying_uv[0][0], varying_uv[0][2] - varying_uv[0][0], 0);
        Vec3f j = AI * Vec3f(varying_uv[1][1] - varying_uv[1][0], varying_uv[1][2] - varying_uv[1][0], 0);

        mat<3,3,float> B;
        B.set_col(0, i.normalize());
        B.set_col(1, j.normalize());
        B.set_col(2, bn);

        Vec3f n = (B*m_model->normal(uv)).normalize();

        float diff = b3Min(b3Max(0.f, n*m_light_dir_local+0.6f),1.f);
        color = m_model->diffuse(uv)*diff;

        return false;
    }
};

/*
struct TinyRenderObjectData
{
    //Camera
    Matrix m_viewMatrix;
    Matrix m_projectionMatrix;
    Matrix m_viewPortMatrix;

    //Model (vertices, indices, textures, shader)
    Matrix m_modelMatrix;    
    class Model*  m_model;
    class IShader* m_shader;
    
        
    //Output
    TGAImage m_rgbColorBuffer;
    b3AlignedObjectArray<float> m_depthBuffer;
};
*/

TinyRenderObjectData::TinyRenderObjectData(int width, int height, const char* fileName)
:m_width(width),
m_height(height),
m_rgbColorBuffer(width,height,TGAImage::RGB),
m_model(0)
{
    Vec3f       eye(1,1,3);
    Vec3f    center(0,0,0);
    Vec3f        up(0,1,0);
    
    m_viewMatrix = lookat(eye, center, up);
    m_viewportMatrix = viewport(width/8, height/8, width*3/4, height*3/4);
    m_projectionMatrix = projection(-1.f/(eye-center).norm());


    m_depthBuffer.resize(width*height);
 //todo(erwincoumans) move the file loading out of here
   char relativeFileName[1024];
    if (!b3ResourcePath::findResourcePath(fileName, relativeFileName, 1024))
    {
        printf("Cannot find file %s\n", fileName);
    } else
    {
        m_model = new Model(relativeFileName);
    }
    
    
}

TinyRenderObjectData::~TinyRenderObjectData()
{
    delete m_model;
}

void TinyRenderer::renderObject(TinyRenderObjectData& renderData)
{
     const char* fileName = "obj/floor.obj";
    
  

//new Model(relativeFileName);//argv[m]);
    Model* model = renderData.m_model;
    if (0==model)
        return;
    
    const int width = renderData.m_width;
    const int height = renderData.m_height;
    b3AlignedObjectArray<float>& zbuffer = renderData.m_depthBuffer;
    
    //todo(erwincoumans) make this a separate call    
    for (int i=width*height; i--; zbuffer[i] = -std::numeric_limits<float>::max());

    TGAImage& frame = renderData.m_rgbColorBuffer;
    
    //lookat(eye, center, up);
    //viewport(width/8, height/8, width*3/4, height*3/4);
    //projection(-1.f/(eye-center).norm());
    
    Vec3f light_dir_local = proj<3>((renderData.m_projectionMatrix*renderData.m_viewMatrix*embed<4>(light_dir_world, 0.f))).normalize();

    {
    //for (int m=1; m<argc; m++) {
        
        Shader shader(model, light_dir_local, renderData.m_viewMatrix, renderData.m_projectionMatrix);
        for (int i=0; i<model->nfaces(); i++) {
            for (int j=0; j<3; j++) {
                shader.vertex(i, j);
            }
            triangle(shader.varying_tri, shader, frame, &zbuffer[0], renderData.m_viewportMatrix);
        }
        
    }
    //frame.flip_vertically(); // to place the origin in the bottom left corner of the image
    //frame.write_tga_file("framebuffer.tga");

        
}