Pileus Git - grits/blob - examples/tex/tex.c

   1 /*
   2  * Copyright (C) 2009-2010 Andy Spencer <andy753421@gmail.com>
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <gtk/gtk.h>
  19 #include <gtk/gtkgl.h>
  20 #include <gdk/gdkkeysyms.h>
  21 #include <GL/gl.h>
  22 #include <GL/glu.h>
  23
  24 #define crazy_draw(tex) \
  25         for (int _i = 0; ({ \
  26                 if (_i == 0) { \
  27                         /* Clear alpha buffer */ \
  28                         glBindTexture(GL_TEXTURE_2D, tex); \
  29                         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); \
  30                         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); \
  31                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER); \
  32                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER); \
  33                         glBlendFuncSeparate(GL_ZERO, GL_ONE, GL_ONE, GL_ZERO); \
  34                 } else if (_i == 1) { \
  35                         /* Draw pixels */ \
  36                         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); \
  37                         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); \
  38                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); \
  39                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); \
  40                         glBlendFuncSeparate(GL_DST_ALPHA, GL_ONE_MINUS_DST_ALPHA, GL_ZERO, GL_ZERO); \
  41                 } else { \
  42                         glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA); \
  43                 } \
  44         }), _i < 2; _i++)
  45
  46 guint tex, texl, texr;
  47
  48 gboolean on_key_press(GtkWidget *widget, GdkEventKey *event, gpointer _)
  49 {
  50         if (event->keyval == GDK_q)
  51                 gtk_main_quit();
  52         return FALSE;
  53 }
  54
  55 gboolean on_expose(GtkWidget *drawing, GdkEventExpose *event, gpointer _)
  56 {
  57         gdouble y = 0;
  58
  59         /* Setup view */
  60         glMatrixMode(GL_PROJECTION);
  61         glLoadIdentity();
  62         glOrtho(-1,1, -1,1, 10,-10);
  63         glMatrixMode(GL_MODELVIEW);
  64         glLoadIdentity();
  65         glTranslatef(0, 0, -5);
  66         glClearColor(0.5, 0.5, 1.0, 1.0);
  67         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  68
  69         /* Draw white background rectangle */
  70         glEnable(GL_COLOR_MATERIAL);
  71         glDisable(GL_TEXTURE_2D);
  72         glColor3f(1.0, 1.0, 1.0);
  73         glBegin(GL_QUADS);
  74         glVertex3f(-0.25, -0.75, 0.0);
  75         glVertex3f(-0.25,  0.75, 0.0);
  76         glVertex3f( 0.25,  0.75, 0.0);
  77         glVertex3f( 0.25, -0.75, 0.0);
  78         glEnd();
  79
  80         /* Setup for textures */
  81         glEnable(GL_TEXTURE_2D);
  82         glEnable(GL_BLEND);
  83         glColor4f(1.0, 1.0, 1.0, 1.0);
  84         glDisable(GL_COLOR_MATERIAL);
  85
  86         /* Left */
  87         crazy_draw(texl) {
  88                 glBegin(GL_QUADS);
  89                 glTexCoord2f( 0.0, y);     glVertex3f(-0.75,  0.0, 0.0);
  90                 glTexCoord2f( 0.0, 1.0);   glVertex3f(-0.75,  0.5, 0.0);
  91                 glTexCoord2f( 2.0, 1.0);   glVertex3f( 0.75,  0.5, 0.0);
  92                 glTexCoord2f( 2.0, y);     glVertex3f( 0.75,  0.0, 0.0);
  93                 glEnd();
  94         }
  95
  96         /* Right */
  97         crazy_draw(texr) {
  98                 glBegin(GL_QUADS);
  99                 glTexCoord2f(-1.0, y);     glVertex3f(-0.75, 0.0, 0.0);
 100                 glTexCoord2f(-1.0, 1.0);   glVertex3f(-0.75, 0.5, 0.0);
 101                 glTexCoord2f( 1.0, 1.0);   glVertex3f( 0.75, 0.5, 0.0);
 102                 glTexCoord2f( 1.0, y);     glVertex3f( 0.75, 0.0, 0.0);
 103                 glEnd();
 104         }
 105
 106         /* Bottom */
 107         glBindTexture(GL_TEXTURE_2D, tex);
 108         glBegin(GL_QUADS);
 109         glTexCoord2f( 0.0, 0.0);   glVertex3f(-0.75, -0.5, 0.0);
 110         glTexCoord2f( 0.0, 1.0-y); glVertex3f(-0.75, -0.0, 0.0);
 111         glTexCoord2f( 1.0, 1.0-y); glVertex3f( 0.75, -0.0, 0.0);
 112         glTexCoord2f( 1.0, 0.0);   glVertex3f( 0.75, -0.5, 0.0);
 113         glEnd();
 114
 115         /* Flush */
 116         GdkGLDrawable *gldrawable = gdk_gl_drawable_get_current();
 117         if (gdk_gl_drawable_is_double_buffered(gldrawable))
 118                 gdk_gl_drawable_swap_buffers(gldrawable);
 119         else
 120                 glFlush();
 121         return FALSE;
 122 }
 123 gboolean on_configure(GtkWidget *drawing, GdkEventConfigure *event, gpointer _)
 124 {
 125         glViewport(0, 0,
 126                 drawing->allocation.width,
 127                 drawing->allocation.height);
 128         return FALSE;
 129 }
 130
 131 guint load_tex(gchar *filename)
 132 {
 133         GdkPixbuf *pixbuf = gdk_pixbuf_new_from_file(filename, NULL);
 134         guchar    *pixels = gdk_pixbuf_get_pixels(pixbuf);
 135         int        width  = gdk_pixbuf_get_width(pixbuf);
 136         int        height = gdk_pixbuf_get_height(pixbuf);
 137         int        alpha  = gdk_pixbuf_get_has_alpha(pixbuf);
 138         guint      tex;
 139         glGenTextures(1, &tex);
 140         glBindTexture(GL_TEXTURE_2D, tex);
 141         glTexImage2D(GL_TEXTURE_2D, 0, 4, width, height, 0,
 142                         (alpha ? GL_RGBA : GL_RGB), GL_UNSIGNED_BYTE, pixels);
 143         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 144         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 145
 146         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
 147         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
 148         g_object_unref(pixbuf);
 149         return tex;
 150 }
 151
 152 int main(int argc, char **argv)
 153 {
 154         gtk_init(&argc, &argv);
 155
 156         GtkWidget   *window   = gtk_window_new(GTK_WINDOW_TOPLEVEL);
 157         GtkWidget   *drawing  = gtk_drawing_area_new();
 158         GdkGLConfig *glconfig = gdk_gl_config_new_by_mode((GdkGLConfigMode)(
 159                         GDK_GL_MODE_RGBA   | GDK_GL_MODE_DEPTH |
 160                         GDK_GL_MODE_DOUBLE | GDK_GL_MODE_ALPHA));
 161         g_signal_connect(window,  "destroy",         G_CALLBACK(gtk_main_quit), NULL);
 162         g_signal_connect(window,  "key-press-event", G_CALLBACK(on_key_press),  NULL);
 163         g_signal_connect(drawing, "expose-event",    G_CALLBACK(on_expose),     NULL);
 164         g_signal_connect(drawing, "configure-event", G_CALLBACK(on_configure),  NULL);
 165         gtk_widget_set_gl_capability(drawing, glconfig, NULL, TRUE, GDK_GL_RGBA_TYPE);
 166         gtk_container_add(GTK_CONTAINER(window), drawing);
 167         gtk_widget_show_all(window);
 168
 169         /* OpenGL setup */
 170         GdkGLContext  *glcontext  = gtk_widget_get_gl_context(GTK_WIDGET(drawing));
 171         GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(GTK_WIDGET(drawing));
 172         gdk_gl_drawable_gl_begin(gldrawable, glcontext);
 173
 174         /* Load texture */
 175         texl = load_tex("texls.png");
 176         texr = load_tex("texrs.png");
 177         tex  = load_tex("tex.png");
 178
 179         gtk_main();
 180
 181         gdk_gl_drawable_gl_end(gldrawable);
 182 }