3 files changed, 280 insertions, 0 deletions
diff --git a/wimmel.frag b/wimmel.frag
new file mode 100644
index 0000000..d4cb7ef
--- /dev/null
+++ b/wimmel.frag
@@ -0,0 +1,27 @@
+varying vec2 v_texcoord;
+uniform sampler2D tex;
+uniform vec2 pixelsize;
+uniform vec4 search_rect;
+uniform int barrier;
+
+void
+main()
+{
+	float i, j;
+	float width = search_rect[2];
+	float height = search_rect[3];
+	int diff = 0;
+
+	for (i = 0.0; i < width && diff < barrier; i += pixelsize.x) {
+		for (j = 0.0; j < height && diff < barrier; j += pixelsize.y) {
+			vec4 match = texture2D(tex, search_rect.xy + vec2(i,j));
+			vec4 orig = texture2D(tex, v_texcoord + vec2(i,j));
+
+			diff += int(any(greaterThan(abs(orig - match), vec4(0.2))));
+		}
+	}
+
+	gl_FragColor = vec4(float(diff < barrier), 0.0, 0.0, 0.0);
+}
+
+// vim:ft=c:
diff --git a/wimmel.vert b/wimmel.vert
new file mode 100644
index 0000000..fe26ecc
--- /dev/null
+++ b/wimmel.vert
@@ -0,0 +1,10 @@
+uniform mat4 proj;
+attribute vec4 position;
+attribute vec2 texcoord;
+varying vec2 v_texcoord;
+
+void main()
+{
+	gl_Position = proj * position;
+	v_texcoord = texcoord;
+}
diff --git a/wimmel_gl.c b/wimmel_gl.c
new file mode 100644
index 0000000..4d6456e
--- /dev/null
+++ b/wimmel_gl.c
@@ -0,0 +1,243 @@
+#include <glib.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#define GL_GLEXT_PROTOTYPES
+#include <GL/glut.h>
+#include <GL/gl.h>
+#include <GL/glext.h>
+
+int window = 0;
+GLuint vbo;
+GLint proj_uniform, tex_uniform, pixelsize_uniform,
+      search_rect_uniform, barrier_uniform;
+GLuint texture;
+int width, height;
+GLuint program;
+GdkPixbuf *pixbuf;
+int x1, y1;
+int mwidth, mheight;
+
+static int
+init_shaders()
+{
+	GLuint v, f;
+	GError *error;
+	gsize length;
+	gchar *p;
+	char msg[512];
+	GLfloat vertices[4 * 5];
+	GLint status;
+
+	g_file_get_contents("wimmel.vert", &p, &length, &error);
+	v = glCreateShader(GL_VERTEX_SHADER);
+	glShaderSource(v, 1, (const GLchar **) &p, NULL);
+	glCompileShader(v);
+	glGetShaderiv(v, GL_COMPILE_STATUS, &status);
+	g_free(p);
+	if (!status) {
+		glGetShaderInfoLog(v, sizeof msg, NULL, msg);
+		fprintf(stderr, "vertex shader info: %s\n", msg);
+		return -1;
+	}
+
+	g_file_get_contents("wimmel.frag", &p, &length, &error);
+
+	f = glCreateShader(GL_FRAGMENT_SHADER);
+	glShaderSource(f, 1, (const GLchar **) &p, NULL);
+	glCompileShader(f);
+	glGetShaderiv(f, GL_COMPILE_STATUS, &status);
+	g_free(p);
+	if (!status) {
+		glGetShaderInfoLog(f, sizeof msg, NULL, msg);
+		fprintf(stderr, "fragment shader info: %s\n", msg);
+		return -1;
+	}
+
+	program = glCreateProgram();
+	glAttachShader(program, v);
+	glAttachShader(program, f);
+	glBindAttribLocation(program, 0, "position");
+	glBindAttribLocation(program, 1, "texcoord");
+
+	glLinkProgram(program);
+	glGetProgramiv(program, GL_LINK_STATUS, &status);
+	if (!status) {
+		glGetProgramInfoLog(program, sizeof msg, NULL, msg);
+		fprintf(stderr, "link info: %s\n", msg);
+		return -1;
+	}
+
+	glUseProgram(program);
+	proj_uniform = glGetUniformLocation(program, "proj");
+	tex_uniform = glGetUniformLocation(program, "tex");
+	pixelsize_uniform = glGetUniformLocation(program, "pixelsize");
+	search_rect_uniform = glGetUniformLocation(program, "search_rect");
+	barrier_uniform = glGetUniformLocation(program, "barrier");
+
+	vertices[ 0] = 0.0;
+	vertices[ 1] = 0.0;
+	vertices[ 2] = 0.0;
+	vertices[ 3] = 0.0;
+	vertices[ 4] = 0.0;
+
+	vertices[ 5] = 0.0;
+	vertices[ 6] = 1.0;
+	vertices[ 7] = 0.0;
+	vertices[ 8] = 0.0;
+	vertices[ 9] = 1.0;
+
+	vertices[10] = 1.0;
+	vertices[11] = 0.0;
+	vertices[12] = 0.0;
+	vertices[13] = 1.0;
+	vertices[14] = 0.0;
+
+	vertices[15] = 1.0;
+	vertices[16] = 1.0;
+	vertices[17] = 0.0;
+	vertices[18] = 1.0;
+	vertices[19] = 1.0;
+
+	glGenBuffers(1, &vbo);
+	glBindBuffer(GL_ARRAY_BUFFER, vbo);
+	glBufferData(GL_ARRAY_BUFFER, sizeof vertices, vertices, GL_STATIC_DRAW);
+
+	return 0;
+}
+
+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;
+	GLenum format;
+
+	glGenTextures(1, &texture);
+	glBindTexture(GL_TEXTURE_2D, texture);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+	data = gdk_pixbuf_get_pixels(pixbuf);
+
+	if (gdk_pixbuf_get_has_alpha(pixbuf))
+		format = GL_RGBA;
+	else
+		format = GL_RGB;
+
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
+		     width, height, 0,
+		     format, GL_UNSIGNED_BYTE, data);
+}
+
+static void
+draw(void)
+{
+	float pixelsize[] = { 1.0 / width, 1.0 / height };
+	static GLfloat proj[16] = {
+		 2.,  0., 0., 0.,
+		 0., -2., 0., 0.,
+		 0.,  0., 1., 0.,
+		-1.,  1., 0., 1.
+	};
+	float search[4];
+	int barrier = mwidth * mheight / 2;
+	static int frames = 0;
+	static int last_time = 0;
+	int elapsed = glutGet(GLUT_ELAPSED_TIME);
+
+	++frames;
+	if ((elapsed - last_time) >= 5000) {
+		printf("fps: %d\n", frames / 5);
+		last_time = elapsed;
+		frames = 0;
+	}
+
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+	glUniformMatrix4fv(proj_uniform, 1, GL_FALSE, proj);
+	glUniform1i(tex_uniform, 0);
+	glUniform2fv(pixelsize_uniform, 1, pixelsize);
+
+	search[0] = 1.0 * x1 / width;
+	search[1] = 1.0 * y1 / height;
+	search[2] = 1.0 * mwidth / width;
+	search[3] = 1.0 * mheight / height;
+
+	glUniform4fv(search_rect_uniform, 1, search);
+	glUniform1i(barrier_uniform, barrier);
+
+	glDisable(GL_BLEND);
+
+	glBindTexture(GL_TEXTURE_2D, texture);
+	glBindBuffer(GL_ARRAY_BUFFER, vbo);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GL_FLOAT), NULL);
+	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GL_FLOAT), (GLfloat *)0 + 3);
+
+	glEnableVertexAttribArray(0);
+	glEnableVertexAttribArray(1);
+
+	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+
+	glutSwapBuffers();
+	printf("finished\n");
+
+}
+
+int
+main(int argc, char **argv)
+{
+	g_type_init();
+
+	glutInit(&argc, argv);
+	if (argc <= 1)
+		return 1;
+
+	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)
+		return 1;
+
+	width  = gdk_pixbuf_get_width(pixbuf);
+	height = gdk_pixbuf_get_height(pixbuf);
+
+	x1 = atoi(argv[2]);
+	y1 = atoi(argv[3]);
+	mwidth = atoi(argv[4]);
+	mheight = atoi(argv[5]);
+
+	glutInitWindowSize(width, height);
+	window = glutCreateWindow("wimmel");
+
+	glutDisplayFunc(draw);
+	glutKeyboardFunc(keypress);
+	glutReshapeFunc(resize);
+
+	init_shaders();
+	create_texture(pixbuf);
+	glViewport(0,0,width,height);
+
+	glutMainLoop();
+
+	return 0;
+}