draw_line.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   draw_line.c                                        :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: kamitsui <kamitsui@student.42tokyo.jp>     +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2024/08/26 14:34:59 by kamitsui          #+#    #+#             */
/*   Updated: 2024/09/30 17:57:29 by kamitsui         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */
 
#include "cub3d.h"
 
// propo is: Proportion of moving points to line span
static int  transition_color(int start, int end, int move_point, t_clr *color)
{
    int span;
    int propo;
    int tr_r;
    int tr_g;
    int tr_b;
 
    span = end - start;
    propo = (move_point - start) * 255 / span;
    tr_r = color->start_r + ((color->end_r - color->start_r) * propo) / 255;
    tr_g = color->start_g + ((color->end_g - color->start_g) * propo) / 255;
    tr_b = color->start_b + ((color->end_b - color->start_b) * propo) / 255;
    return ((tr_r << 16) | (tr_g << 8) | tr_b);
}
 
static int  get_current_color(t_plot *plot, t_line *line, t_clr *color)
{
    int start;
    int end;
    int move_point;
 
    if (plot->dx > 0)
    {
        start = line->x_start;
        end = line->x_end;
        move_point = plot->px;
    }
    else
    {
        start = line->y_start;
        end = line->y_end;
        move_point = plot->py;
    }
    return (transition_color(start, end, move_point, color));
}
 
//#include "ft_printf.h"
//void  debug_line(int x_start, int y_start, int color0,
//      int x_end, int y_end, int color1)
//{
//  ft_printf("\n\n---- draw_line ----  start -> end\n");
//  ft_printf("start\tx_start:%d y_start:%d color0:%X\n",
//      x_start, y_start, color0);
//  ft_printf("end  \tx_end:%d y_end:%d color1:%X\n", x_end, y_end, color1);
//}
//
//void  debug_count(int px, int py, int pc)
//{
//  static int i = 0;
//  ft_printf("draw_loop : %d\tpx:%d\tpy:%d\tpc:%X\n", i++, px, py, pc);
//}
//  debug_line(line->x_start, line->y_start, line->color0,
//  line->x_end, line->y_end, line->color1);
//      debug_count(plot->px, plot->py, plot->pc);
 
static void draw_loop(t_plot *plot, t_line *line, t_clr *color, t_img *img)
{
    while (1)
    {
        if (plot->px >= IMG_2D_WIDTH || plot->px <= 0
            || plot->py >= IMG_2D_HEIGHT || plot->py <= 0)
            break ;
        plot->pc = get_current_color(plot, line, color);
        my_mlx_pixel_put(img, plot->px, plot->py, plot->pc);
        if (plot->px == line->x_end && plot->py == line->y_end)
            break ;
        plot->err2 = 2 * plot->err;
        if (plot->err2 > -plot->dy)
        {
            plot->err -= plot->dy;
            plot->px += plot->sx;
        }
        if (plot->err2 < plot->dx)
        {
            plot->err += plot->dx;
            plot->py += plot->sy;
        }
    }
}
 
// memo : develop unfinished
// Bresenham's line algorithm
void    draw_line(t_img *img, t_line *line)
{
    t_plot  plot;
    t_clr   color;
 
    init_plot(&plot, line);
    init_color(&color, line->color_start, line->color_end);
    draw_loop(&plot, line, &color, img);
}