text_text.cpp

#if 0 /* (sh-mode) 
set -e

LPATH=/Users/cro/Documents/PersonalProjects/Graphics/

# -Ofast
[ ! ]&& time clang++ -g  --std=c++11 -fPIC -Wall \
  $LPATH/text_test.cpp \
  -Wno-writable-strings \
  -Wno-unused-function \
  -Wno-deprecated-declarations \
  -framework Cocoa -framework AppKit -framework OpenGL \
  -F /Library/Frameworks/ -framework SDL2 \
  -o $LPATH/text_test.cpp.elf

[ ! ]&&{
 cd $RPATH
 ulimit -c unlimited
 rm -fv core
 pwd
 time $LPATH/text_test.cpp.elf
}

true
exit # (c++-mode) */
#endif

#if defined __APPLE__
#include <SDL2/SDL.h>
#include <SDL2/SDL_opengl.h>
#else
#include <SDL.h>
#include <SDL_opengl.h>
#endif

#define check_gl_error() _check_gl_error(__FILE__,__LINE__)
void _check_gl_error(const char *file, int line) {
	GLenum err (glGetError());
	const char * error;

	switch (err) {
		case GL_INVALID_OPERATION:      error = "INVALID_OPERATION";      break;
		case GL_INVALID_ENUM:           error = "INVALID_ENUM";           break;
		case GL_INVALID_VALUE:          error = "INVALID_VALUE";          break;
		case GL_OUT_OF_MEMORY:          error = "OUT_OF_MEMORY";          break;
		case GL_INVALID_FRAMEBUFFER_OPERATION:  error = "INVALID_FRAMEBUFFER_OPERATION";  break;
		default:
			error = "UNKNOWN";
	}


	while(err!=GL_NO_ERROR) {
		SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "%s:%d OPENGL_ERROR %s\n", file, line, error);
		err=glGetError();
	}
}

#define STB_TRUETYPE_IMPLEMENTATION  // force following include to generate implementation
#include "stb/stb_truetype.h"

unsigned char ttf_buffer[1<<20];
unsigned char temp_bitmap[2048*2048];

stbtt_bakedchar cdata[96]; // ASCII 32..126 is 95 glyphs
GLuint ftex;

void my_stbtt_initfont(void)
{
    auto f = fopen("/Users/cro/Downloads/IndieFlower.ttf", "rb");
    assert(f);
   fread(ttf_buffer, 1, 1<<20, f);
   stbtt_BakeFontBitmap(ttf_buffer,0, 64.0, temp_bitmap,2048,2048, 32,96, cdata); // no guarantee this fits!
   // can free ttf_buffer at this point
   glGenTextures(1, &ftex);
   glBindTexture(GL_TEXTURE_2D, ftex);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, 512,512, 0, GL_ALPHA, GL_UNSIGNED_BYTE, temp_bitmap);
   // can free temp_bitmap at this point
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
}

void my_stbtt_print(float x, float y, char *text)
{
   // assume orthographic projection with units = screen pixels, origin at top left
   glEnable(GL_TEXTURE_2D);
   glBindTexture(GL_TEXTURE_2D, ftex);
   glBegin(GL_QUADS);
   while (*text) {
       if (*text >= 32) { // && *text < 128
         stbtt_aligned_quad q;
         stbtt_GetBakedQuad(cdata, 512,512, *text-32, &x,&y,&q,1);//1=opengl & d3d10+,0=d3d9
         glTexCoord2f(q.s0,q.t1); glVertex2f(q.x0,q.y0);
         glTexCoord2f(q.s1,q.t1); glVertex2f(q.x1,q.y0);
         glTexCoord2f(q.s1,q.t0); glVertex2f(q.x1,q.y1);
         glTexCoord2f(q.s0,q.t0); glVertex2f(q.x0,q.y1);
      }
      ++text;
   }
   glEnd();
}

int main() {


	int render_width = 100;
	int render_height = 100;



	//Create window
	SDL_Window * window = SDL_CreateWindow
	(
	 "Untitled Window",
	 SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
	 render_width, render_height,
	 SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE | SDL_WINDOW_OPENGL

	 );

	if(!window)
	{
		SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "Window could not be created! SDL_Error: %s\n", SDL_GetError() );
		return -1;
	}


	SDL_GLContext context = SDL_GL_CreateContext( window );
	if( context == NULL )
	{
		SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "OpenGL context could not be created! SDL Error: %s\n", SDL_GetError() );
		return -3;
	}

	if( SDL_GL_SetSwapInterval( 1 ) < 0 )
	{
		SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "Warning: Unable to set VSync! SDL Error: %s\n", SDL_GetError() );
	}


    glEnable(GL_TEXTURE_2D);
    my_stbtt_initfont();



	bool has_focus = false;
	bool running = true;

	while(running) {

		SDL_Event e;
		while(SDL_PollEvent( &e )) {
			switch (e.type) {
				case SDL_WINDOWEVENT:
					if (e.window.event == SDL_WINDOWEVENT_FOCUS_GAINED) {
						has_focus = true;
					} else if (e.window.event == SDL_WINDOWEVENT_FOCUS_LOST) {
						has_focus = false;
					}
					break;
				case SDL_QUIT:
					running = false;
					break;
				default:
					break;
			}
		}

//		if (!has_focus) {
//			SDL_Delay(50);
//			continue;
//		}


        glMatrixMode(GL_PROJECTION);
        int window_width, window_height;
        SDL_GetWindowSize(window, &window_width, &window_height);
        glViewport(0, 0, window_width, window_height);

        glClearColor(.5f,.0f,.5f,.5f);
        glClear(GL_COLOR_BUFFER_BIT);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(0, 200, 200, 0, 10, -10);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();


        my_stbtt_print(10, 20, "hello how are you?");
        


        SDL_GL_SwapWindow(window);
        check_gl_error();

	}
	return 0;
}