wimmel: Render to a fbo

2 files changed, 54 insertions, 28 deletions

diff --git a/wimmel.frag b/wimmel.frag
index d4cb7ef..d3cf745 100644
--- a/wimmel.frag
+++ b/wimmel.frag
@@ -21,7 +21,7 @@ main()
 		}
 	}
 
-	gl_FragColor = vec4(float(diff < barrier), 0.0, 0.0, 0.0);
+	gl_FragColor = vec4(float(diff < barrier), 0.0, 0.0, 1.0);
 }
 
 // vim:ft=c:
diff --git a/wimmel_gl.c b/wimmel_gl.c
index 4d6456e..223a9de 100644
--- a/wimmel_gl.c
+++ b/wimmel_gl.c
@@ -6,7 +6,7 @@
 #include <GL/gl.h>
 #include <GL/glext.h>
 
-int window = 0;
+//int window = 0;
 GLuint vbo;
 GLint proj_uniform, tex_uniform, pixelsize_uniform,
       search_rect_uniform, barrier_uniform;
@@ -106,23 +106,6 @@ init_shaders()
 }
 
 static void
-keypress(unsigned char key, int x, int y)
-{
-	switch (key) {
-	case 27:
-		glutDestroyWindow(window);
-		exit(0);
-		break;
-    	}
-}
-
-static void
-resize(int w, int h)
-{
-	glViewport(0, 0, w, h);
-}
-
-static void
 create_texture(GdkPixbuf *pixbuf)
 {
 	void *data;
@@ -170,7 +153,7 @@ draw(void)
 		frames = 0;
 	}
 
-	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+	glClear(GL_COLOR_BUFFER_BIT);
 
 	glUniformMatrix4fv(proj_uniform, 1, GL_FALSE, proj);
 	glUniform1i(tex_uniform, 0);
@@ -196,7 +179,7 @@ draw(void)
 
 	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 
-	glutSwapBuffers();
+	glFinish();
 	printf("finished\n");
 
 }
@@ -212,7 +195,6 @@ main(int argc, char **argv)
 
 	glutInitDisplayMode(GLUT_RGBA /*| GLUT_DEPTH */ | GLUT_DOUBLE);
 
-	glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
 
 	pixbuf = gdk_pixbuf_new_from_file(argv[1], NULL);
 	if (!pixbuf)
@@ -226,18 +208,62 @@ main(int argc, char **argv)
 	mwidth = atoi(argv[4]);
 	mheight = atoi(argv[5]);
 
-	glutInitWindowSize(width, height);
-	window = glutCreateWindow("wimmel");
+	glutInitWindowSize(1,1);
+	int window = glutCreateWindow("wimmel");
+	glutDestroyWindow(window);
+
+	GLuint fb, rb;
+
+	glGenFramebuffersEXT(1, &fb);
+	glGenRenderbuffersEXT(1, &rb);
 
-	glutDisplayFunc(draw);
-	glutKeyboardFunc(keypress);
-	glutReshapeFunc(resize);
+	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fb);
+	glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, rb);
+
+	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT,
+				     GL_COLOR_ATTACHMENT0_EXT,
+				     GL_RENDERBUFFER_EXT,
+				     rb);
+	glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT,
+				 GL_RGBA,
+				 width, height);
+
+	if (glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT) !=
+	    GL_FRAMEBUFFER_COMPLETE_EXT) {
+		fprintf(stderr, "framebuffer not complete\n");
+		return 1;
+	}
 
 	init_shaders();
 	create_texture(pixbuf);
 	glViewport(0,0,width,height);
 
-	glutMainLoop();
+	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+
+	draw();
+
+	glPixelStorei(GL_PACK_ALIGNMENT, 2);
+
+	gint stride = width * 4;
+	guchar *buffer = malloc(stride * height);
+	glReadPixels(0, 0, width, height,
+		     GL_RGBA, GL_UNSIGNED_BYTE,
+		     buffer);
+
+	GdkPixbuf *t_output, *output;
+
+	t_output = gdk_pixbuf_new_from_data(buffer,
+					  GDK_COLORSPACE_RGB,
+					  TRUE, 8,
+					  width, height, stride,
+					  NULL, NULL);
+	output = gdk_pixbuf_flip(t_output, FALSE);
+
+	gdk_pixbuf_save(output, "output_gl.png", "png", NULL, NULL);
+	g_object_unref(output);
+	g_object_unref(t_output);
+	free(buffer);
+	g_object_unref(pixbuf);
 
 	return 0;
 }