wimmel_gl: Use luminance textures

2 files changed, 33 insertions, 28 deletions

diff --git a/wimmel.frag b/wimmel.frag
index 42b0139..22adcf9 100644
--- a/wimmel.frag
+++ b/wimmel.frag
@@ -17,7 +17,8 @@ main()
 			vec4 orig = texture2D(tex, v_texcoord + vec2(i,j));
 			vec4 match = texture2D(tex2, vec2(i, j) / srect.zw);
 
-			diff += int(any(greaterThan(abs(orig - match), vec4(0.2))));
+			if (abs(orig.r - match.r) > 0.08)
+				++diff;
 		}
 	}
 
diff --git a/wimmel_gl.c b/wimmel_gl.c
index 631be54..0f271af 100644
--- a/wimmel_gl.c
+++ b/wimmel_gl.c
@@ -128,12 +128,35 @@ align(int value, int alignment)
    return (value + alignment - 1) & ~(alignment - 1);
 }
 
+guchar *
+monochrome(GdkPixbuf *p)
+{
+	int x, y, width, height, nch;
+	guchar *d, *data;
+
+	width = gdk_pixbuf_get_width(p);
+	height = gdk_pixbuf_get_height(p);
+	nch = gdk_pixbuf_get_n_channels(p);
+
+	data = malloc(width * height);
+	if (!data)
+		return NULL;
+
+	for (y = 0; y < height; ++y) {
+		d = gdk_pixbuf_get_pixels(p) + y * gdk_pixbuf_get_rowstride(p);
+		for (x = 0; x < width; ++x, d += nch) {
+			data[y*width + x] = MAX(d[0], MAX(d[1], d[2]));
+		}
+	}
+
+	return data;
+}
+
 static void
 create_texture(GdkPixbuf *pixbuf, GLuint *texture, int i)
 {
-	guchar *data, *buffer = NULL;
-	int width, height, stride, nch, new_stride;
-	GLenum format;
+	guchar *data;
+	int width, height;
 
 	glActiveTexture(GL_TEXTURE0 + i);
 	glGenTextures(1, texture);
@@ -143,34 +166,15 @@ create_texture(GdkPixbuf *pixbuf, GLuint *texture, int i)
 	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;
-	
 	width = gdk_pixbuf_get_width(pixbuf);
 	height = gdk_pixbuf_get_height(pixbuf);
-	stride = gdk_pixbuf_get_rowstride(pixbuf);
-	nch = gdk_pixbuf_get_n_channels(pixbuf);
-
-	new_stride = align(nch * width, 4);
-
-	if (stride != new_stride) {
-		buffer = malloc(new_stride * height);
-		for (int row = 0; row < height; ++row)
-			memcpy(buffer + row * new_stride,
-			       data + row * stride,
-			       width * nch);
-		data = buffer;
-	}
+	data = monochrome(pixbuf);
 
-	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
+	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE,
 		     width, height, 0,
-		     format, GL_UNSIGNED_BYTE, data);
-	if (buffer != NULL)
-		free(buffer);
+		     GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
+	free(data);
 }
 
 static void