nolibgs_hello_worlds/hello_world/hello_world.c

// Demonstrate DISP/DRAW env, font setup, and display a text.
// Schnappy 2020
// Based on Lameguy64 tutorial : http://lameguy64.net/svn/pstutorials/chapter1/1-display.html
#include <sys/types.h>
#include <stdio.h>
#include <libgte.h>
#include <libetc.h>
#include <libgpu.h>
#define VMODE 0                 // Video Mode : 0 : NTSC, 1: PAL
#define SCREENXRES 320          // Screen width
#define SCREENYRES 240          // Screen height
#define CENTERX SCREENXRES/2    // Center of screen on x 
#define CENTERY SCREENYRES/2    // Center of screen on y
#define MARGINX 0                // margins for text display
#define MARGINY 32
#define FONTSIZE 8 * 7           // Text Field Height
DISPENV disp[2];                 // Double buffered DISPENV and DRAWENV
DRAWENV draw[2];
short db = 0;                      // index of which buffer is used, values 0, 1
void init(void)
{
    ResetGraph(0);                 // Initialize drawing engine with a complete reset (0)
    SetDefDispEnv(&disp[0], 0, 0         , SCREENXRES, SCREENYRES);     // Set display area for both &disp[0] and &disp[1]
    SetDefDispEnv(&disp[1], 0, SCREENYRES, SCREENXRES, SCREENYRES);     // &disp[0] is on top  of &disp[1]
    SetDefDrawEnv(&draw[0], 0, SCREENYRES, SCREENXRES, SCREENYRES);     // Set draw for both &draw[0] and &draw[1]
    SetDefDrawEnv(&draw[1], 0, 0         , SCREENXRES, SCREENYRES);     // &draw[0] is below &draw[1]
    if (VMODE)                  // PAL
    {
        SetVideoMode(MODE_PAL);
        disp[0].screen.y += 8;  // add offset : 240 + 8 + 8 = 256
        disp[1].screen.y += 8;
        }
    SetDispMask(1);                 // Display on screen    
    setRGB0(&draw[0], 50, 50, 50); // set color for first draw area
    setRGB0(&draw[1], 50, 50, 50); // set color for second draw area
    draw[0].isbg = 1;               // set mask for draw areas. 1 means repainting the area with the RGB color each frame 
    draw[1].isbg = 1;
    PutDispEnv(&disp[db]);          // set the disp and draw environnments
    PutDrawEnv(&draw[db]);
    FntLoad(960, 0);                // Load font to vram at 960,0(+128)
    FntOpen(MARGINX, SCREENYRES - MARGINY - FONTSIZE, SCREENXRES - MARGINX * 2, FONTSIZE, 0, 280 ); // FntOpen(x, y, width, height,  black_bg, max. nbr. chars
}
void display(void)
{
    DrawSync(0);                    // Wait for all drawing to terminate
    VSync(0);                       // Wait for the next vertical blank
    PutDispEnv(&disp[db]);          // set alternate disp and draw environnments
    PutDrawEnv(&draw[db]);  
    db = !db;                       // flip db value (0 or 1)
}
int main(void)
{
    init();                         // execute init()
    while (1)                       // infinite loop
    {   
        FntPrint("Hello world !");  // Send string to print stream
        FntFlush(-1);               // Draw printe stream
        display();                  // Execute display()
    }
    return 0;
    }