Trouble having SDL_TTF and OPENGL work together - c++

Question

For a game I'm working on, I'm hoping to use OpenGL for a lot of the graphics and SDL_TTF for the text. I can get both to work but not at the same time. Here's my code (based off Lazy Foo):
#include "SDL/SDL.h"
#include "SDL/SDL_ttf.h"
#include "GL/gl.h"
const bool useOpenGl = true;
//The surfaces
SDL_Surface *message = NULL;
SDL_Surface *screen = NULL;
//The event structure
SDL_Event event;
//The font that's going to be used
TTF_Font *font = NULL;
//The color of the font
SDL_Color textColor = {255, 255, 255};
void apply_surface(int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL)
{
//Holds offsets
SDL_Rect offset;
//Get offsets
offset.x = x;
offset.y = y;
//Blit
SDL_BlitSurface(source, clip, destination, &offset);
}
bool init()
{
SDL_Init (SDL_INIT_EVERYTHING);
if (useOpenGl)
{
screen = SDL_SetVideoMode (1280, 720, 32, SDL_SWSURFACE | SDL_OPENGL); //With SDL_OPENGL flag only opengl is sceen, without only text is
} else {
screen = SDL_SetVideoMode (1280, 720, 32, SDL_SWSURFACE);
}
TTF_Init();
SDL_WM_SetCaption ("TTF Not Working With OpenGL", NULL);
if (useOpenGl)
{
glClearColor(1.0, 0.0, 0.0, 0.0);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, screen->w, screen->h, 1.0, -1.0, 1.0);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}
return true;
}
bool load_files()
{
font = TTF_OpenFont ("arial.ttf", 28);
return true;
}
void clean_up()
{
SDL_FreeSurface (message);
TTF_CloseFont (font);
TTF_Quit();
SDL_Quit();
}
int main(int argc, char* args[])
{
//Quit flag
bool quit = false;
init();
load_files();
if (useOpenGl)
{
glClear(GL_COLOR_BUFFER_BIT); //clearing the screen
glPushMatrix();
glBegin(GL_QUADS);
glColor3f(1.0, 0.0, 0.0);
glVertex2f(0, 0);
glColor3f(0.0, 1.0, 0.0);
glVertex2f(1280, 0);
glColor3f(0.0, 0.0, 1.0);
glVertex2f(1280, 720);
glColor4f(0.5, 0.5, 1.0, 0.1);
glVertex2f(0, 720);
glEnd();
glPopMatrix();
glFlush();
}
//Render the text
message = TTF_RenderText_Solid (font, "The quick brown fox jumps over the lazy dog", textColor);
//Apply the images to the screen
apply_surface (0, 150, message, screen);
//I'm guessing this is where the problem is coming from
SDL_GL_SwapBuffers();
SDL_Flip (screen);
while (quit == false)
{
while (SDL_PollEvent (&event))
{
if (event.type == SDL_QUIT)
{
quit = true;
}
}
}
clean_up();
return 0;
}
If the variable useOpenGl is set to false the program will only use SDL_TTF, if it's set to true it will use both SDL_TTF and OpenGL.
From playing around with it the problem seems to be with whether or not I use the "SDL_OPENGL" flag when creating the window.

Answer 1

SDL_TTF uses software rendering and is not compatible with OpenGL mode.
You might have to look for another library such as FTGL or freetype-gl.