gl-renderer: move vertex shader into new file

This patch adds the tooling for incorporating files as C data, so that
files can be built into the binaries. The tool is in Python to avoid
adding extra dependencies like xxd.

xxd.py is copied from Mesa as-is, from commit
b729cd58d76f97f3fc04a67569535ee5ef2f5278 (master branch on 2021-01-26),
a.k.a 21.0-branchpoint-635-gb729cd58d76.

Moving the GLSL vertex shader into a separate file is not that
interesting, the purpose of this commit is to provide a simple
demonstration of the tooling. The real benefits come in a following
patch where the fragment shaders are re-written and externalized.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

libweston/renderer-gl/gl-shaders.c

@@ -32,16 +32,8 @@
 #include "gl-renderer.h"
 #include "gl-renderer-internal.h"
 
-static const char vertex_shader[] =
-	"uniform mat4 proj;\n"
-	"attribute vec2 position;\n"
-	"attribute vec2 texcoord;\n"
-	"varying vec2 v_texcoord;\n"
-	"void main()\n"
-	"{\n"
-	"   gl_Position = proj * vec4(position, 0.0, 1.0);\n"
-	"   v_texcoord = texcoord;\n"
-	"}\n";
+/* static const char vertex_shader[]; vertex.glsl */
+#include "vertex-shader.h"
 
 /* Declare common fragment shader uniforms */
 #define FRAGMENT_CONVERT_YUV						\

libweston/renderer-gl/meson.build

@@ -4,12 +4,20 @@ endif
 
 config_h.set('ENABLE_EGL', '1')
 
+vertex_glsl = custom_target(
+	'vertex-shader.h',
+	command: cmd_xxd + [ '-n', 'vertex_shader' ],
+	input: 'vertex.glsl',
+	output: 'vertex-shader.h',
+)
+
 srcs_renderer_gl = [
 	'egl-glue.c',
 	'gl-renderer.c',
 	'gl-shaders.c',
 	linux_dmabuf_unstable_v1_protocol_c,
 	linux_dmabuf_unstable_v1_server_protocol_h,
+	vertex_glsl,
 ]
 
 deps_renderer_gl = [

libweston/renderer-gl/vertex.glsl

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012 Intel Corporation
+ * Copyright 2015,2019 Collabora, Ltd.
+ * Copyright 2016 NVIDIA Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+uniform mat4 proj;
+attribute vec2 position;
+attribute vec2 texcoord;
+varying vec2 v_texcoord;
+
+void main()
+{
+	gl_Position = proj * vec4(position, 0.0, 1.0);
+	v_texcoord = texcoord;
+}