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

   1 #define GL_GLEXT_PROTOTYPES
   2 #include <gtk/gtk.h>
   3 #include <gtk/gtkgl.h>
   4 #include <gdk/gdkkeysyms.h>
   5 #include <GL/gl.h>
   6 #include <GL/glext.h>
   7
   8 gchar *gl_program_log(guint program, int *_len)
   9 {
  10         gchar *buf = NULL;
  11         int len = 0;
  12         glGetProgramiv(program, GL_INFO_LOG_LENGTH, &len);
  13         if (len > 0) {
  14                 buf = g_malloc(len);
  15                 glGetProgramInfoLog(program, len, &len, buf);
  16         }
  17         if (_len)
  18                 *_len = len;
  19         return buf;
  20 }
  21
  22 void on_key_press(GtkWidget *widget, GdkEventKey *event, gpointer user_data)
  23 {
  24         g_message("key-press");
  25         if (event->keyval == GDK_q)
  26                 gtk_main_quit();
  27 }
  28
  29 gboolean on_expose(GtkWidget *drawing, GdkEventExpose *event, gpointer _)
  30 {
  31         glClearColor(0.5, 0.5, 1.0, 1.0);
  32         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  33
  34         glMatrixMode(GL_PROJECTION);
  35         glLoadIdentity();
  36         glOrtho(-1,1, -1,1, 10,-10);
  37         glMatrixMode(GL_MODELVIEW);
  38         glLoadIdentity();
  39         glTranslatef(0, 0, -5);
  40
  41         glEnable(GL_COLOR_MATERIAL);
  42         glDisable(GL_TEXTURE_2D);
  43         glColor3f(1.0, 1.0, 1.0);
  44         glBegin(GL_QUADS);
  45         glVertex3f(-0.25, -0.75, 0.0);
  46         glVertex3f(-0.25,  0.75, 0.0);
  47         glVertex3f( 0.25,  0.75, 0.0);
  48         glVertex3f( 0.25, -0.75, 0.0);
  49         glEnd();
  50
  51         /* Test projection */
  52         gdouble model[16], proj[16];
  53         gint view[4];
  54         glGetDoublev (GL_MODELVIEW_MATRIX,  model);
  55         glGetDoublev (GL_PROJECTION_MATRIX, proj);
  56         glGetIntegerv(GL_VIEWPORT,          view);
  57         gdouble x=0.25, y=-0.75, z=0.0;
  58         gdouble px, py, pz;
  59         gluProject(x, y, z, model, proj, view, &px, &py, &pz);
  60         g_message("%f,%f,%f -> %f,%f,%f", x, y, z, px, py, pz);
  61
  62         /* Textures */
  63         glDisable(GL_COLOR_MATERIAL);
  64         glEnable(GL_TEXTURE_2D);
  65         glEnable(GL_BLEND);
  66
  67         /* Flush */
  68         GdkGLDrawable *gldrawable = gdk_gl_drawable_get_current();
  69         if (gdk_gl_drawable_is_double_buffered(gldrawable))
  70                 gdk_gl_drawable_swap_buffers(gldrawable);
  71         else
  72                 glFlush();
  73         return FALSE;
  74 }
  75
  76 gboolean on_configure(GtkWidget *drawing, GdkEventConfigure *event, gpointer _)
  77 {
  78         glViewport(0, 0,
  79                 drawing->allocation.width,
  80                 drawing->allocation.height);
  81         return FALSE;
  82 }
  83
  84 int main(int argc, char **argv)
  85 {
  86         gtk_init(&argc, &argv);
  87
  88         GtkWidget   *window   = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  89         GtkWidget   *drawing  = gtk_drawing_area_new();
  90         GdkGLConfig *glconfig = gdk_gl_config_new_by_mode((GdkGLConfigMode)(
  91                         GDK_GL_MODE_RGBA   | GDK_GL_MODE_DEPTH |
  92                         GDK_GL_MODE_DOUBLE | GDK_GL_MODE_ALPHA));
  93         g_signal_connect(window,  "destroy",         G_CALLBACK(gtk_main_quit), NULL);
  94         g_signal_connect(window,  "key-press-event", G_CALLBACK(on_key_press),  NULL);
  95         g_signal_connect(drawing, "expose-event",    G_CALLBACK(on_expose),     NULL);
  96         g_signal_connect(drawing, "configure-event", G_CALLBACK(on_configure),  NULL);
  97         gtk_widget_set_gl_capability(drawing, glconfig, NULL, TRUE, GDK_GL_RGBA_TYPE);
  98         gtk_container_add(GTK_CONTAINER(window), drawing);
  99         gtk_widget_show_all(window);
 100
 101         /* OpenGL setup */
 102         GdkGLContext  *glcontext  = gtk_widget_get_gl_context(GTK_WIDGET(drawing));
 103         GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(GTK_WIDGET(drawing));
 104
 105         /* Setup shader */
 106         gdk_gl_drawable_gl_begin(gldrawable, glcontext);
 107
 108         gchar *source;
 109         gboolean status = g_file_get_contents("shader.glsl", &source, NULL, NULL);
 110         if (!status)
 111                 g_error("Failed to load shader");
 112
 113         guint program = glCreateProgram();
 114         if (!program)
 115                 g_error("Error creating program");
 116
 117         guint shader = glCreateShader(GL_VERTEX_SHADER_ARB);
 118         if (!shader)
 119                 g_error("Error creating shader");
 120
 121         glShaderSource(shader, 1, (const gchar**)&source, NULL);
 122         if (glGetError())
 123                 g_error("Error setting shader source");
 124
 125         glCompileShader(shader);
 126         if (glGetError())
 127                 g_error("Error compiling shader");
 128
 129         glAttachShader(program, shader);
 130         if (glGetError())
 131                 g_error("Error attaching shader");
 132
 133         glLinkProgram(program);
 134         if (glGetError())
 135                 g_error("Error linking program");
 136
 137         glUseProgram(program);
 138         if (glGetError())
 139                 g_error("Error using program:\n%s", gl_program_log(program, NULL));
 140
 141         /* Run */
 142         gtk_main();
 143
 144         /* Clean up */
 145         glDetachShader(program, shader);
 146         glDeleteShader(shader);
 147         glDeleteProgram(program);
 148
 149         gdk_gl_drawable_gl_end(gldrawable);
 150         return 0;
 151 }