Pileus Git - grits/blob - examples/shader/shader.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 #define GL_GLEXT_PROTOTYPES
  19 #include <gtk/gtk.h>
  20 #include <gtk/gtkgl.h>
  21 #include <gdk/gdkkeysyms.h>
  22 #include <GL/gl.h>
  23 #include <GL/glext.h>
  24
  25 gchar *gl_program_log(guint program, int *_len)
  26 {
  27         gchar *buf = NULL;
  28         int len = 0;
  29         glGetProgramiv(program, GL_INFO_LOG_LENGTH, &len);
  30         if (len > 0) {
  31                 buf = g_malloc(len);
  32                 glGetProgramInfoLog(program, len, &len, buf);
  33         }
  34         if (_len)
  35                 *_len = len;
  36         return buf;
  37 }
  38
  39 void on_key_press(GtkWidget *widget, GdkEventKey *event, gpointer user_data)
  40 {
  41         g_message("key-press");
  42         if (event->keyval == GDK_q)
  43                 gtk_main_quit();
  44 }
  45
  46 gboolean on_expose(GtkWidget *drawing, GdkEventExpose *event, gpointer _)
  47 {
  48         glClearColor(0.5, 0.5, 1.0, 1.0);
  49         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  50
  51         glMatrixMode(GL_PROJECTION);
  52         glLoadIdentity();
  53         glOrtho(-1,1, -1,1, 10,-10);
  54         glMatrixMode(GL_MODELVIEW);
  55         glLoadIdentity();
  56         glTranslatef(0, 0, -5);
  57
  58         glEnable(GL_COLOR_MATERIAL);
  59         glDisable(GL_TEXTURE_2D);
  60         glColor3f(1.0, 1.0, 1.0);
  61         glBegin(GL_QUADS);
  62         glVertex3f(-0.25, -0.75, 0.0);
  63         glVertex3f(-0.25,  0.75, 0.0);
  64         glVertex3f( 0.25,  0.75, 0.0);
  65         glVertex3f( 0.25, -0.75, 0.0);
  66         glEnd();
  67
  68         /* Test projection */
  69         gdouble model[16], proj[16];
  70         gint view[4];
  71         glGetDoublev (GL_MODELVIEW_MATRIX,  model);
  72         glGetDoublev (GL_PROJECTION_MATRIX, proj);
  73         glGetIntegerv(GL_VIEWPORT,          view);
  74         gdouble x=0.25, y=-0.75, z=0.0;
  75         gdouble px, py, pz;
  76         gluProject(x, y, z, model, proj, view, &px, &py, &pz);
  77         g_message("%f,%f,%f -> %f,%f,%f", x, y, z, px, py, pz);
  78
  79         /* Textures */
  80         glDisable(GL_COLOR_MATERIAL);
  81         glEnable(GL_TEXTURE_2D);
  82         glEnable(GL_BLEND);
  83
  84         /* Flush */
  85         GdkGLDrawable *gldrawable = gdk_gl_drawable_get_current();
  86         if (gdk_gl_drawable_is_double_buffered(gldrawable))
  87                 gdk_gl_drawable_swap_buffers(gldrawable);
  88         else
  89                 glFlush();
  90         return FALSE;
  91 }
  92
  93 gboolean on_configure(GtkWidget *drawing, GdkEventConfigure *event, gpointer _)
  94 {
  95         glViewport(0, 0,
  96                 drawing->allocation.width,
  97                 drawing->allocation.height);
  98         return FALSE;
  99 }
 100
 101 int main(int argc, char **argv)
 102 {
 103         gtk_init(&argc, &argv);
 104
 105         GtkWidget   *window   = gtk_window_new(GTK_WINDOW_TOPLEVEL);
 106         GtkWidget   *drawing  = gtk_drawing_area_new();
 107         GdkGLConfig *glconfig = gdk_gl_config_new_by_mode((GdkGLConfigMode)(
 108                         GDK_GL_MODE_RGBA   | GDK_GL_MODE_DEPTH |
 109                         GDK_GL_MODE_DOUBLE | GDK_GL_MODE_ALPHA));
 110         g_signal_connect(window,  "destroy",         G_CALLBACK(gtk_main_quit), NULL);
 111         g_signal_connect(window,  "key-press-event", G_CALLBACK(on_key_press),  NULL);
 112         g_signal_connect(drawing, "expose-event",    G_CALLBACK(on_expose),     NULL);
 113         g_signal_connect(drawing, "configure-event", G_CALLBACK(on_configure),  NULL);
 114         gtk_widget_set_gl_capability(drawing, glconfig, NULL, TRUE, GDK_GL_RGBA_TYPE);
 115         gtk_container_add(GTK_CONTAINER(window), drawing);
 116         gtk_widget_show_all(window);
 117
 118         /* OpenGL setup */
 119         GdkGLContext  *glcontext  = gtk_widget_get_gl_context(GTK_WIDGET(drawing));
 120         GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(GTK_WIDGET(drawing));
 121
 122         /* Setup shader */
 123         gdk_gl_drawable_gl_begin(gldrawable, glcontext);
 124
 125         gchar *source;
 126         gboolean status = g_file_get_contents("shader.glsl", &source, NULL, NULL);
 127         if (!status)
 128                 g_error("Failed to load shader");
 129
 130         guint program = glCreateProgram();
 131         if (!program)
 132                 g_error("Error creating program");
 133
 134         guint shader = glCreateShader(GL_VERTEX_SHADER_ARB);
 135         if (!shader)
 136                 g_error("Error creating shader");
 137
 138         glShaderSource(shader, 1, (const gchar**)&source, NULL);
 139         if (glGetError())
 140                 g_error("Error setting shader source");
 141
 142         glCompileShader(shader);
 143         if (glGetError())
 144                 g_error("Error compiling shader");
 145
 146         glAttachShader(program, shader);
 147         if (glGetError())
 148                 g_error("Error attaching shader");
 149
 150         glLinkProgram(program);
 151         if (glGetError())
 152                 g_error("Error linking program");
 153
 154         glUseProgram(program);
 155         if (glGetError())
 156                 g_error("Error using program:\n%s", gl_program_log(program, NULL));
 157
 158         /* Run */
 159         gtk_main();
 160
 161         /* Clean up */
 162         glDetachShader(program, shader);
 163         glDeleteShader(shader);
 164         glDeleteProgram(program);
 165
 166         gdk_gl_drawable_gl_end(gldrawable);
 167         return 0;
 168 }