main.cpp

#include <iostream>
#include "tgaimage.h"
#include "model.h"
#include "geometry.h"
#include "triangle.h"
#include "transform.h"


const TGAColor white = TGAColor(255, 255, 255, 255);
const TGAColor red 	 = TGAColor(255, 0  , 0  , 255);
const TGAColor green = TGAColor(0  , 255, 0  , 255);
const TGAColor blue  = TGAColor(0  , 0  , 255, 255);

const int width = 1200;
const int height = 1200;
const int depth = 255;


// vec3f cam(0.8, 0.7, 5.0);
// vec3f target(9.0,0.15,1.5);

vec3f cam(0,0,-5);
vec3f target(0,0,0);

Model* model = NULL;
double *zbuffer = NULL;

void INIT_ZBUF(void){
	zbuffer = new double[width*height];
	for(int i = width*height ; i >= 0 ; i--){
		zbuffer[i] = -std::numeric_limits<float>::max();
	}
	return;
}

vec3i world2screen(vec3f w){
	//convert them to display on screen , map [-1,1] to [0,width] and [0,height] 
	return vec3i(int((w.x + 1.0f) * width / 2.0f), int((w.y + 1.0f) * height / 2.0f),w.z);
}

void untex_render(vec3f light_dir, double *zbuffer, Model *model, TGAImage &image) {
	mat4 view_port = viewport(width/8,height/8,width*3/4,height*3/4,depth);
	// mat4 view_port = viewport(0,0,width,height);
	mat4 proj = mat4::identity();
	proj[3][2] = 1.0f/cam.z;

	for (size_t i = 0; i < model->nfaces(); i++) {
		// std::vector<int> face = model->face(i);

		vec3f screen_coords[3];//screen coordinates of triangle associated with ith face
		vec3f world_coords[3];

		for (size_t j = 0; j < 3; j++) {

			vec3f v = model->vert(i, j); //get the jth vertex of ith face, these have components as just numbers in the range [-1,1]

			//convert them to display on screen , map [-1,1] to [0,width] and [0,height] 
			screen_coords[j] = embed<3>(view_port*proj*embed<4>(v));
			world_coords[j] = v;
		}

		vec3f n = cross(world_coords[2] - world_coords[0], world_coords[1] - world_coords[0]); //calculate normal to triangle

		n.normalize();
		double intensity = dot(n, light_dir);

		if (intensity > 0) {
			// TGAColor clr = TGAColor(0,intensity*255,intensity*255);
			// triangle(screen_coords,zbuffer, image, clr);

			untex_triangle(screen_coords,zbuffer, image, TGAColor(static_cast<uint8_t>(intensity * 255), static_cast<uint8_t>(intensity * 255), static_cast<uint8_t>(intensity * 255)));			
		}
	}
}

void render(vec3f light_dir, double *zbuffer, Model *model, TGAImage &image) {
	
	mat4 view_port = viewport(0,0,width,height,depth);
	// mat4 view_port = viewport(width/8,height/8,width*3/4,height*3/4);

	mat4 proj = projection(30.0f,static_cast<float>(width/height),-1.0f,-10.0f);
	mat4 model_view = lookat(cam,target,vec3f(0,1,0));

	for (size_t i = 0; i < model->nfaces(); i++) {

		vec3f screen_coords[3];	//screen coords of triangle associated with ith face
		vec3f world_coords[3];	//world coords of triangle associated with ith face
		vec2f uv_coords[3];		//uv coords of vertices of triangle associated with ith face

		for (size_t j = 0; j < 3; j++) {

			vec3f v = model->vert(i, j); //get the jth vertex of ith face, these have components as just numbers in the range [-1,1]

			world_coords[j] = v;

			//MVP Trasnform , here model matrix is Identity because only one object in the scene with no change in oreintation or position
			auto tmp = proj*model_view*embed<4>(v);
			
			//perspective division
			for(int i = 0 ; i < 4 ; i++){
				tmp[i] = tmp[i] / tmp[3];	
			} 

			tmp = view_port*tmp; 

			screen_coords[j] = embed<3>(tmp);
			screen_coords[j].z *= -1.0f; // z-buffer doesnt work if I don't do this, probably due to how I've implemented the projection matrix
			
			uv_coords[j] = model->uv(i,j);			
		}

		//calculate normal to triangle
		vec3f n = cross(world_coords[2] - world_coords[0], world_coords[1] - world_coords[0]); 
		n.normalize();

		//Lmabertian lighting
		double intensity = dot(n, light_dir);

		if (intensity > 0) {
			triangle(screen_coords,uv_coords,zbuffer,image,model);			
		}
	}

	TGAImage depth(width, height, TGAImage::GRAYSCALE);
	for(size_t h = 0 ; h < height ; h++){
		for(size_t w = 0 ; w < width ; w++){
			depth.set(h,w,static_cast<uint8_t>((zbuffer[w * height + h] + 1) * 255));
		}
	}
	depth.write_tga_file("depth.tga");
}

int main(int argc, char** argv) {

	if (argc == 2) {
		model = new Model(argv[1]);
	}
	else {
		model = new Model("obj/african_head.obj",true,false,false);		
	}

	//Initialize z-buffer
	INIT_ZBUF();

	TGAImage image(width, height, TGAImage::RGB);

	vec3f light_dir = (target-cam).normalize();
	// vec3f light_dir = vec3f(1,-1,1).normalize();

	// untex_render(light_dir,zbuffer,model,image);
	render(light_dir,zbuffer,model,image);

	image.write_tga_file("output.tga");
	delete model;

	return 0;
}