Adding OpenGL shader (GLSL) example

diff --git a/examples/shader/.gitignore b/examples/shader/.gitignore
new file mode 100644 (file)
index 0000000..a47742a
--- /dev/null
+++ b/examples/shader/.gitignore
@@ -0,0 +1 @@
+shader

diff --git a/examples/shader/mkfile b/examples/shader/mkfile
new file mode 100644 (file)
index 0000000..bba13dd
--- /dev/null
+++ b/examples/shader/mkfile
@@ -0,0 +1,4 @@
+PROGS=shader
+PKGS=gtkglext-1.0
+defualt:V: shader-run
+<$HOME/lib/mkcommon

diff --git a/examples/shader/shader.c b/examples/shader/shader.c
new file mode 100644 (file)
index 0000000..3d6d3d4
--- /dev/null
+++ b/examples/shader/shader.c
@@ -0,0 +1,151 @@
+#define GL_GLEXT_PROTOTYPES
+#include <gtk/gtk.h>
+#include <gtk/gtkgl.h>
+#include <gdk/gdkkeysyms.h>
+#include <GL/gl.h>
+#include <GL/glext.h>
+
+gchar *gl_program_log(guint program, int *_len)
+{
+       gchar *buf = NULL;
+       int len = 0;
+       glGetProgramiv(program, GL_INFO_LOG_LENGTH, &len);
+       if (len > 0) {
+               buf = g_malloc(len);
+               glGetProgramInfoLog(program, len, &len, buf);
+       }
+       if (_len)
+               *_len = len;
+       return buf;
+}
+
+void on_key_press(GtkWidget *widget, GdkEventKey *event, gpointer user_data)
+{
+       g_message("key-press");
+       if (event->keyval == GDK_q)
+               gtk_main_quit();
+}
+
+gboolean on_expose(GtkWidget *drawing, GdkEventExpose *event, gpointer _)
+{
+       glClearColor(0.5, 0.5, 1.0, 1.0);
+       glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+       glMatrixMode(GL_PROJECTION);
+       glLoadIdentity();
+       glOrtho(-1,1, -1,1, 10,-10);
+       glMatrixMode(GL_MODELVIEW);
+       glLoadIdentity();
+       glTranslatef(0, 0, -5);
+
+       glEnable(GL_COLOR_MATERIAL);
+       glDisable(GL_TEXTURE_2D);
+       glColor3f(1.0, 1.0, 1.0);
+       glBegin(GL_QUADS);
+       glVertex3f(-0.25, -0.75, 0.0);
+       glVertex3f(-0.25,  0.75, 0.0);
+       glVertex3f( 0.25,  0.75, 0.0);
+       glVertex3f( 0.25, -0.75, 0.0);
+       glEnd();
+
+       /* Test projection */
+       gdouble model[16], proj[16];
+       gint view[4];
+       glGetDoublev (GL_MODELVIEW_MATRIX,  model);
+       glGetDoublev (GL_PROJECTION_MATRIX, proj);
+       glGetIntegerv(GL_VIEWPORT,          view);
+       gdouble x=0.25, y=-0.75, z=0.0;
+       gdouble px, py, pz;
+       gluProject(x, y, z, model, proj, view, &px, &py, &pz);
+       g_message("%f,%f,%f -> %f,%f,%f", x, y, z, px, py, pz);
+
+       /* Textures */
+       glDisable(GL_COLOR_MATERIAL);
+       glEnable(GL_TEXTURE_2D);
+       glEnable(GL_BLEND);
+
+       /* Flush */
+       GdkGLDrawable *gldrawable = gdk_gl_drawable_get_current();
+       if (gdk_gl_drawable_is_double_buffered(gldrawable))
+               gdk_gl_drawable_swap_buffers(gldrawable);
+       else
+               glFlush();
+       return FALSE;
+}
+
+gboolean on_configure(GtkWidget *drawing, GdkEventConfigure *event, gpointer _)
+{
+       glViewport(0, 0,
+               drawing->allocation.width,
+               drawing->allocation.height);
+       return FALSE;
+}
+
+int main(int argc, char **argv)
+{
+       gtk_init(&argc, &argv);
+
+       GtkWidget   *window   = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+       GtkWidget   *drawing  = gtk_drawing_area_new();
+       GdkGLConfig *glconfig = gdk_gl_config_new_by_mode((GdkGLConfigMode)(
+                       GDK_GL_MODE_RGBA   | GDK_GL_MODE_DEPTH |
+                       GDK_GL_MODE_DOUBLE | GDK_GL_MODE_ALPHA));
+       g_signal_connect(window,  "destroy",         G_CALLBACK(gtk_main_quit), NULL);
+       g_signal_connect(window,  "key-press-event", G_CALLBACK(on_key_press),  NULL);
+       g_signal_connect(drawing, "expose-event",    G_CALLBACK(on_expose),     NULL);
+       g_signal_connect(drawing, "configure-event", G_CALLBACK(on_configure),  NULL);
+       gtk_widget_set_gl_capability(drawing, glconfig, NULL, TRUE, GDK_GL_RGBA_TYPE);
+       gtk_container_add(GTK_CONTAINER(window), drawing);
+       gtk_widget_show_all(window);
+
+       /* OpenGL setup */
+       GdkGLContext  *glcontext  = gtk_widget_get_gl_context(GTK_WIDGET(drawing));
+       GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(GTK_WIDGET(drawing));
+
+       /* Setup shader */
+       gdk_gl_drawable_gl_begin(gldrawable, glcontext);
+
+       gchar *source;
+       gboolean status = g_file_get_contents("shader.glsl", &source, NULL, NULL);
+       if (!status)
+               g_error("Failed to load shader");
+
+       guint program = glCreateProgram();
+       if (!program)
+               g_error("Error creating program");
+
+       guint shader = glCreateShader(GL_VERTEX_SHADER_ARB);
+       if (!shader)
+               g_error("Error creating shader");
+
+       glShaderSource(shader, 1, (const gchar**)&source, NULL);
+       if (glGetError())
+               g_error("Error setting shader source");
+
+       glCompileShader(shader);
+       if (glGetError())
+               g_error("Error compiling shader");
+
+       glAttachShader(program, shader);
+       if (glGetError())
+               g_error("Error attaching shader");
+
+       glLinkProgram(program);
+       if (glGetError())
+               g_error("Error linking program");
+
+       glUseProgram(program);
+       if (glGetError())
+               g_error("Error using program:\n%s", gl_program_log(program, NULL));
+
+       /* Run */
+       gtk_main();
+
+       /* Clean up */
+       glDetachShader(program, shader);
+       glDeleteShader(shader);
+       glDeleteProgram(program);
+
+       gdk_gl_drawable_gl_end(gldrawable);
+       return 0;
+}

diff --git a/examples/shader/shader.glsl b/examples/shader/shader.glsl
new file mode 100644 (file)
index 0000000..38b76d9
--- /dev/null
+++ b/examples/shader/shader.glsl
@@ -0,0 +1,7 @@
+void main()
+{
+       gl_Position =
+               gl_ModelViewProjectionMatrix *
+               ( gl_Vertex + 0.5 );
+       gl_Position[3] = 1;
+}