gtk/demos/gtk-demo/glarea.c
2014-10-13 10:43:31 -04:00

185 lines
4.3 KiB
C

/* OpenGL Area
*
* GtkGLArea is a widget that allows custom drawing using OpenGL calls.
*/
#include <gtk/gtk.h>
#include <epoxy/gl.h>
static GtkWidget *demo_window = NULL;
/* the GtkGLArea widget */
static GtkWidget *gl_area = NULL;
enum {
X_AXIS,
Y_AXIS,
Z_AXIS,
N_AXIS
};
/* Rotation angles on each axis */
static float rotation_angles[N_AXIS] = { 0.0 };
/* The object we are drawing */
static void
draw_triangle (void)
{
glColor3f (1.0f, 0.85f, 0.35f);
glBegin (GL_TRIANGLES);
{
glVertex3f ( 0.0, 0.6, 0.0);
glVertex3f (-0.2, -0.3, 0.0);
glVertex3f ( 0.2, -0.3, 0.0);
}
glEnd ();
}
/* The main rendering callback */
static gboolean
render (GtkGLArea *area,
GdkGLContext *context)
{
glClearColor (0.5, 0.5, 0.5, 1.0);
glClear (GL_COLOR_BUFFER_BIT);
glMatrixMode (GL_MODELVIEW);
glLoadIdentity ();
glRotatef (rotation_angles[X_AXIS], 1, 0, 0);
glRotatef (rotation_angles[Y_AXIS], 0, 1, 0);
glRotatef (rotation_angles[Z_AXIS], 0, 0, 1);
draw_triangle ();
glFlush ();
return TRUE;
}
static void
on_axis_value_change (GtkAdjustment *adjustment,
gpointer data)
{
int axis = GPOINTER_TO_INT (data);
g_assert (axis >= 0 && axis < N_AXIS);
/* Update the rotation angle */
rotation_angles[axis] = gtk_adjustment_get_value (adjustment);
/* Update the contents of the GL drawing area */
gtk_widget_queue_draw (gl_area);
}
static GtkWidget *
create_axis_slider (int axis)
{
GtkWidget *box, *label, *slider;
GtkAdjustment *adj;
const char *text;
box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, FALSE);
switch (axis)
{
case X_AXIS:
text = "X axis";
break;
case Y_AXIS:
text = "Y axis";
break;
case Z_AXIS:
text = "Z axis";
break;
default:
g_assert_not_reached ();
}
label = gtk_label_new (text);
gtk_container_add (GTK_CONTAINER (box), label);
gtk_widget_show (label);
adj = gtk_adjustment_new (0.0, 0.0, 360.0, 1.0, 12.0, 0.0);
g_signal_connect (adj, "value-changed",
G_CALLBACK (on_axis_value_change),
GINT_TO_POINTER (axis));
slider = gtk_scale_new (GTK_ORIENTATION_HORIZONTAL, adj);
gtk_container_add (GTK_CONTAINER (box), slider);
gtk_widget_set_hexpand (slider, TRUE);
gtk_widget_show (slider);
gtk_widget_show (box);
return box;
}
static void
close_window (GtkWidget *widget)
{
/* Reset the state */
demo_window = NULL;
gl_area = NULL;
rotation_angles[X_AXIS] = 0.0;
rotation_angles[Y_AXIS] = 0.0;
rotation_angles[Z_AXIS] = 0.0;
}
GtkWidget *
create_glarea_window (GtkWidget *do_widget)
{
GtkWidget *window, *box, *button, *controls;
int i;
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_screen (GTK_WINDOW (window), gtk_widget_get_screen (do_widget));
gtk_window_set_title (GTK_WINDOW (window), "GtkGLArea - Golden Triangle");
gtk_window_set_default_size (GTK_WINDOW (window), 400, 400);
gtk_container_set_border_width (GTK_CONTAINER (window), 12);
g_signal_connect (window, "destroy", G_CALLBACK (close_window), NULL);
box = gtk_box_new (GTK_ORIENTATION_VERTICAL, FALSE);
gtk_box_set_spacing (GTK_BOX (box), 6);
gtk_container_add (GTK_CONTAINER (window), box);
gl_area = gtk_gl_area_new ();
gtk_widget_set_hexpand (gl_area, TRUE);
gtk_widget_set_vexpand (gl_area, TRUE);
gtk_container_add (GTK_CONTAINER (box), gl_area);
/* the main "draw" call for GtkGLArea */
g_signal_connect (gl_area, "render", G_CALLBACK (render), NULL);
controls = gtk_box_new (GTK_ORIENTATION_VERTICAL, FALSE);
gtk_container_add (GTK_CONTAINER (box), controls);
gtk_widget_set_hexpand (controls, TRUE);
for (i = 0; i < N_AXIS; i++)
gtk_container_add (GTK_CONTAINER (controls), create_axis_slider (i));
button = gtk_button_new_with_label ("Quit");
gtk_widget_set_hexpand (button, TRUE);
gtk_container_add (GTK_CONTAINER (box), button);
g_signal_connect_swapped (button, "clicked", G_CALLBACK (gtk_widget_destroy), window);
return window;
}
GtkWidget*
do_glarea (GtkWidget *do_widget)
{
if (demo_window == NULL)
demo_window = create_glarea_window (do_widget);
if (!gtk_widget_get_visible (demo_window))
gtk_widget_show_all (demo_window);
else
gtk_widget_destroy (demo_window);
return demo_window;
}