demo-lcd.c 7.75 KB
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/* =========================================================================
 * Freetype GL - A C OpenGL Freetype engine
 * Platform:    Any
 * WWW:         http://code.google.com/p/freetype-gl/
 * -------------------------------------------------------------------------
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 * Copyright 2011,2012 Nicolas P. Rougier. All rights reserved.
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 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY NICOLAS P. ROUGIER ''AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL NICOLAS P. ROUGIER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and documentation are
 * those of the authors and should not be interpreted as representing official
 * policies, either expressed or implied, of Nicolas P. Rougier.
 * ========================================================================= */
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#include <stdio.h>
#include <wchar.h>

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#include "freetype-gl.h"
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#include "vertex-buffer.h"
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#include "shader.h"
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#include "mat4.h"

#if defined(__APPLE__)
    #include <Glut/glut.h>
#elif defined(_WIN32) || defined(_WIN64)
    #include <GLUT/glut.h>
#else
    #include <GL/glut.h>
#endif

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// ------------------------------------------------------- typedef & struct ---
typedef struct {
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    float x, y, z;
    float u, v;
    float r, g, b, a;
    float shift, gamma;
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} vertex_t;
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// ------------------------------------------------------- global variables ---
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texture_atlas_t *atlas;
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vertex_buffer_t *buffer;
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GLuint shader;
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mat4 model, view, projection;
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// ---------------------------------------------------------------- display ---
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void display( void )
{
    int viewport[4];
    glGetIntegerv( GL_VIEWPORT, viewport );
    glClearColor(1,1,1,1);
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

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    glEnable( GL_TEXTURE_2D );
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    glEnable( GL_COLOR_MATERIAL );
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    glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
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    glColor4f( 0, 0, 0, 1 );
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    glBlendFunc( GL_ONE, GL_ONE_MINUS_SRC_ALPHA );
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    glBlendColor( 1, 1, 1, 1 );
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    glEnable( GL_BLEND );
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    mat4_set_identity( &model );
    mat4_translate( &model, 5, viewport[3], 0);
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    glUseProgram( shader );
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    {
        glUniform1i( glGetUniformLocation( shader, "texture" ),
                     0 );
        glUniform3f(  glGetUniformLocation( shader, "pixel" ),
                      1.0/atlas->width, 1.0/atlas->height, atlas->depth );
        glUniformMatrix4fv( glGetUniformLocation( shader, "model" ),
                            1, 0, model.data);
        glUniformMatrix4fv( glGetUniformLocation( shader, "view" ),
                            1, 0, view.data);
        glUniformMatrix4fv( glGetUniformLocation( shader, "projection" ),
                            1, 0, projection.data);
        glUniformMatrix4fv( glGetUniformLocation( shader, "projection" ),
                            1, 0, projection.data);
        vertex_buffer_render( buffer, GL_TRIANGLES );
    }
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    glutSwapBuffers( );
}

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// ---------------------------------------------------------------- reshape ---
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void reshape(int width, int height)
{
    glViewport(0, 0, width, height);
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    mat4_set_orthographic( &projection, 0, width, 0, height, -1, 1);
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}

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// --------------------------------------------------------------- keyboard ---
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void keyboard( unsigned char key, int x, int y )
{
    if ( key == 27 )
    {
        exit( 1 );
    }
}

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// --------------------------------------------------------------- add_text ---
void add_text( vertex_buffer_t * buffer, texture_font_t * font,
               wchar_t * text, vec4 * color, vec2 * pen )
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{
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    size_t i;
    float r = color->red, g = color->green, b = color->blue, a = color->alpha;
    for( i=0; i<wcslen(text); ++i )
    {
        texture_glyph_t *glyph = texture_font_get_glyph( font, text[i] );
        if( glyph != NULL )
        {
            int kerning = 0;
            if( i > 0)
            {
                kerning = texture_glyph_get_kerning( glyph, text[i-1] );
            }
            pen->x += kerning;
            int x0  = (int)( pen->x + glyph->offset_x );
            int y0  = (int)( pen->y + glyph->offset_y );
            int x1  = (int)( x0 + glyph->width );
            int y1  = (int)( y0 - glyph->height );
            float s0 = glyph->s0;
            float t0 = glyph->t0;
            float s1 = glyph->s1;
            float t1 = glyph->t1;
            GLuint index = buffer->vertices->size;
            GLuint indices[] = {index, index+1, index+2,
                                index, index+2, index+3};
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            vertex_t vertices[] = { { x0,y0,0,  s0,t0,  r,g,b,a, 0,1 },
                                    { x0,y1,0,  s0,t1,  r,g,b,a, 0,1 },
                                    { x1,y1,0,  s1,t1,  r,g,b,a, 0,1 },
                                    { x1,y0,0,  s1,t0,  r,g,b,a, 0,1 } };
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            vertex_buffer_push_back_indices( buffer, indices, 6 );
            vertex_buffer_push_back_vertices( buffer, vertices, 4 );
            pen->x += glyph->advance_x;
        }
    }
}

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// ------------------------------------------------------------------- main ---
int main( int argc, char **argv )
{
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    glutInit( &argc, argv );
    glutInitWindowSize( 800, 400 );
    glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH );
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    glutCreateWindow( "Freetype OpenGL / LCD filtering" );
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    glutReshapeFunc( reshape );
    glutDisplayFunc( display );
    glutKeyboardFunc( keyboard );

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    GLenum err = glewInit();
    if (GLEW_OK != err)
    {
        /* Problem: glewInit failed, something is seriously wrong. */
        fprintf( stderr, "Error: %s\n", glewGetErrorString(err) );
        exit( EXIT_FAILURE );
    }
    fprintf( stderr, "Using GLEW %s\n", glewGetString(GLEW_VERSION) );

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    size_t i;
    texture_font_t *font = 0;
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    atlas = texture_atlas_new( 512, 512, 3 );
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    const char * filename = "fonts/Vera.ttf";
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    wchar_t *text = L"A Quick Brown Fox Jumps Over The Lazy Dog 0123456789";
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    buffer = vertex_buffer_new( "vertex:3f,tex_coord:2f,color:4f,ashift:1f,agamma:1f" ); 
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    vec2 pen = {{0,0}};
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    vec4 color = {{0,0,0,1}};
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    for( i=7; i < 27; ++i)
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    {
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        font = texture_font_new_from_file( atlas, i, filename );
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        pen.x = 0;
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        pen.y -= font->height;
        texture_font_load_glyphs( font, text );
        add_text( buffer, font, text, &color, &pen );
        texture_font_delete( font );
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    }
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    glBindTexture( GL_TEXTURE_2D, atlas->id );
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    shader = shader_load( "shaders/text.vert",
                          "shaders/text.frag" );
    mat4_set_identity( &projection );
    mat4_set_identity( &model );
    mat4_set_identity( &view );

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    glutMainLoop( );
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    return 0;
}