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Schriftart mit SDL_TTF laden

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Lord Horazont

Betreff des Beitrags: Schriftart mit SDL_TTF laden

Verfasst: Di Aug 08, 2006 11:43

DGL Member

Registriert: Do Sep 02, 2004 19:42
Beiträge: 4158
Programmiersprache: FreePascal, C++

Hi @ll

Entweder ich bin zu blöd oder sonstwas.
Ich versuche ne 2D Anwendung mit SDL und OpenGL zu machen.
Das Problem: Ich will Text einbauen. Also muss ich ja wohl eine ttf-Schriftart laden. Am besten mit der Zeile:

Code:

 
TextFont := TTF_OpenFont(PChar('I:\text.ttf'), 12);
 

Allerdings bekomme ich immer nil zurück. Die TTF-Datei liegt da wo der Pfad hinzeigt. Ich habe auch schon ein / anstatt eines \ verwendet, aber es hilft nix.
Wo kann das Problem liegen?
SDL_TTF ist initialisiert (mit TTF_Init)

THX in Advance

Gruß Lord Horazont

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Flash

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Verfasst: Di Aug 08, 2006 13:06

Guitar Hero

Registriert: Do Sep 25, 2003 15:56
Beiträge: 7810
Wohnort: Sachsen - ERZ / C
Programmiersprache: Java (, Pascal)

Ich hab hier nen alten C-Code rumliegen der bei mir funktionierte. Eventuell kannste den mal als Inspiration verwenden.

Code:

 
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
 
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glext.h>
 
#include <SDL.h>
#include <SDL_ttf.h>
 
#ifdef _WIN32
#undef main
#endif
 
/* adjust these accordingly */
char fontpath[] = "C:\\WINDOWS\\Fonts\\ARIBLK.TTF"; 
int screenwidth = 640;
int screenheight = 480;
 
/*int round(double x)
{
    return (int)(x + 0.5);
}*/
 
int nextpoweroftwo(int x)
{
    double logbase2 = log(x) / log(2);
    return round(pow(2,ceil(logbase2)));
}
 
char *init_sdl(SDL_Surface** screen)
{
    if(SDL_Init(SDL_INIT_VIDEO))
        return SDL_GetError();
    atexit(SDL_Quit);
    
    *screen = SDL_SetVideoMode(screenwidth, screenheight, 0, SDL_OPENGL);
    
    SDL_WM_SetCaption("C-Junkie's SDLGL text example", 0);
    
    if(TTF_Init())
        return TTF_GetError();
    atexit(TTF_Quit);
    
    return 0;
}
 
void SDL_GL_RenderText(char *text, 
                      TTF_Font *font,
                      SDL_Color color,
                      SDL_Rect *location)
{
    SDL_Surface *initial;
    SDL_Surface *intermediary;
    //SDL_Rect rect;
    int w,h;
    GLuint texture;
    
    /* Use SDL_TTF to render our text */
    initial = TTF_RenderText_Solid(font, text, color);
    
    /* Convert the rendered text to a known format */
    w = nextpoweroftwo(initial->w);
    h = nextpoweroftwo(initial->h);
    
    intermediary = SDL_CreateRGBSurface(0, w, h, 32, 
            0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000);
 
    SDL_BlitSurface(initial, 0, intermediary, 0);
    
    /* Tell GL about our new texture */
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, 4, w, h, 0, GL_BGRA, 
            GL_UNSIGNED_BYTE, intermediary->pixels );
    
    /* GL_NEAREST looks horrible, if scaled... */
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);   
 
    /* prepare to render our texture */
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, texture);
    glColor3f(1.0f, 1.0f, 1.0f);
    
    /* Draw a quad at location */
    glBegin(GL_QUADS);
        /* Recall that the origin is in the lower-left corner
           That is why the TexCoords specify different corners
           than the Vertex coors seem to. */
        glTexCoord2f(0.0f, 1.0f); 
            glVertex2f(location->x    , location->y);
        glTexCoord2f(1.0f, 1.0f); 
            glVertex2f(location->x + w, location->y);
        glTexCoord2f(1.0f, 0.0f); 
            glVertex2f(location->x + w, location->y + h);
        glTexCoord2f(0.0f, 0.0f); 
            glVertex2f(location->x    , location->y + h);
    glEnd();
    
    /* Bad things happen if we delete the texture before it finishes */
    glFinish();
    
    /* return the deltas in the unused w,h part of the rect */
    location->w = initial->w;
    location->h = initial->h;
    
    /* Clean up */
    SDL_FreeSurface(initial);
    SDL_FreeSurface(intermediary);
    glDeleteTextures(1, &texture);
}
 
void glEnable2D()
{
    int vPort[4];
  
    glGetIntegerv(GL_VIEWPORT, vPort);
  
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    glLoadIdentity();
  
    glOrtho(0, vPort[2], 0, vPort[3], -1, 1);
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glLoadIdentity();
}
 
void glDisable2D()
{
    glMatrixMode(GL_PROJECTION);
    glPopMatrix();   
    glMatrixMode(GL_MODELVIEW);
    glPopMatrix();  
}
 
void init_gl()
{
    /* Irrelevant stuff for this demo */
    glShadeModel(GL_SMOOTH);
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClearDepth(1.0f);
    glDepthFunc(GL_LEQUAL);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
    
    /* Required if you want alpha-blended textures (for our fonts) */
    glBlendFunc(GL_ONE, GL_ONE);
    glEnable(GL_BLEND);
    
    /* Required setup stuff */
    glViewport(0, 0, 800, 600);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0f, screenwidth / (float)screenheight, 0.1f, 50.0f);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();   
}
 
int main()
{
    SDL_Surface *screen;
    TTF_Font* font;
    char *err;
    SDL_Color color;
    SDL_Rect position;
    SDL_Event event;
    int done;
    
    /* Do boring initialization */
    if((err = init_sdl(&screen))) {
        printf("Error while initializing: %s", err);
        return 1;
    }
    
    if(!(font = TTF_OpenFont(fontpath, 20))) {
        printf("Error loading font: %s", TTF_GetError());
        return 1;
    }
    
    init_gl();
 
    done = 0;
    while(!done) {
        /* render a fun litte quad */
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glLoadIdentity();
        glTranslatef(0.0f, 0.0f, -5.0f);
        glDisable(GL_TEXTURE_2D);
        
        glBegin(GL_QUADS);
            glNormal3f(0.0f, 0.0f, 1.0f);
            glColor3f(0.5f, 0.0f, 0.0f); glVertex3f(-1.5f, -1.0f,  1.0f);
            glColor3f(0.0f, 0.5f, 0.0f); glVertex3f( 1.0f, -2.0f,  1.0f);
            glColor3f(0.0f, 0.0f, 0.5f); glVertex3f( 1.5f,  1.0f,  1.0f);
            glColor3f(0.5f, 0.0f, 0.0f); glVertex3f(-2.0f,  1.0f, -1.0f);
        glEnd();
        
        /* Go in HUD-drawing mode */
        glEnable2D();
        glDisable(GL_DEPTH_TEST);
        
        /* Draw some text */
        color.r = 255;
        color.g = 128;
        color.b = 255;
        /** A quick note about position.
         * Enable2D puts the origin in the lower-left corner of the
         * screen, which is different from the normal coordinate
         * space of most 2D api's. position, therefore,
         * gives the X,Y coordinates of the lower-left corner of the
         * rectangle **/
        position.x = screenwidth / 3;
        position.y = screenheight / 2;
        SDL_GL_RenderText("Hello, World!", font, color, &position);
        position.y -= position.h;
        SDL_GL_RenderText("A line right underneath", font, color, &position);
        position.y -= position.h;
        SDL_GL_RenderText("Yay text rendering.", font, color, &position);
 
        /* Come out of HUD mode */
        glEnable(GL_DEPTH_TEST);
        glDisable2D();
        
        /* Show the screen */
        SDL_GL_SwapBuffers( );
        
        /* Wait until you click the X */
    
        SDL_WaitEvent(&event);
        switch(event.type) {
        case SDL_QUIT:
            done = 1;
            break;
        }
    }
    
    /* Clean up (the atexit's take care of the rest) */
    TTF_CloseFont(font);
    
    return 0;
}
 

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Lord Horazont

Betreff des Beitrags:

Verfasst: Di Aug 08, 2006 14:51

DGL Member

Registriert: Do Sep 02, 2004 19:42
Beiträge: 4158
Programmiersprache: FreePascal, C++

Ich werd bei gelegenheit mal das Wiki korrigieren.
Da steht drin, dass TTF_WasInit = 0 heißt, dass schon initalisiert wurde. Das Gegenteil ist aber der fall. Drauf gekommen bin ich durch TTF_GetError. Damit hab ich den Fehler gefunden.

Jetzt gehts.

Gruß Lord Horazont

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