[core] don't rebuild shaders unless they change

1 files changed, 26 insertions, 80 deletions

diff --git a/scripts/build-shaders.py b/scripts/build-shaders.py
index 3f3b776710..226c1a2ecc 100755
--- a/scripts/build-shaders.py
+++ b/scripts/build-shaders.py
@@ -2,10 +2,8 @@
 
 import sys, re, os, errno
 
-
-output_dir = sys.argv[1]
-file_names = sys.argv[2:]
-
+input_file = sys.argv[1]
+output_file = sys.argv[2]
 
 def mkdir_p(path):
     try:
@@ -15,92 +13,40 @@ def mkdir_p(path):
             pass
         else: raise
 
-# Load all shaders
-shaders = {}
-for file_name in file_names:
-    parts = re.search('/(\w+)\.(vertex|fragment)\.glsl$', file_name)
-    if parts:
-        shader_name = parts.group(1)
-        shader_type = parts.group(2)
-        if not shader_name in shaders:
-            shaders[shader_name] = {}
-        with open(file_name, "r") as f:
-            shaders[shader_name][shader_type] = f.read()
+shader_name, shader_type, extension = os.path.basename(input_file).split('.')
 
+with open(input_file, "r") as f:
+    data = f.read()
 
-def write_header():
-    header = """// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.
+content = """// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.
 
-#ifndef MBGL_SHADER_SHADERS
-#define MBGL_SHADER_SHADERS
+#ifndef MBGL_SHADER_{NAME}_{TYPE}
+#define MBGL_SHADER_{NAME}_{TYPE}
 
 #include <mbgl/platform/gl.hpp>
 
-namespace mbgl {
-
-struct shader_source {
-    const GLchar *vertex;
-    const GLchar *fragment;
-};
-
-enum {
-%s
-    SHADER_COUNT
-};
-
-extern const shader_source shaders[SHADER_COUNT];
-
-}
+namespace mbgl {{
+namespace shaders {{
+namespace {name} {{
 
+#ifdef GL_ES_VERSION_2_0
+constexpr const char* {type} = R"MBGL_SHADER(precision highp float;\n{data})MBGL_SHADER";
+#else
+constexpr const char* {type} = R"MBGL_SHADER(#version 120\n{data})MBGL_SHADER";
 #endif
-""" % '\n'.join(['    %s_SHADER,' % name.upper() for name in shaders.keys()])
-    header_path = os.path.join(output_dir, 'include/mbgl/shader/shaders.hpp')
-    mkdir_p(os.path.dirname(header_path))
-    with open(header_path, 'w') as f: f.write(header)
-
 
-def write_source(shader_platform, prefix, suffix):
-    if shader_platform == 'gles2' or shader_platform == 'gles3':
-        # OpenGL ES
-        preamble = 'precision highp float;';
-    else:
-        # Desktop OpenGL
-        preamble = '#version 120';
+}} // namespace {name}
+}} // namespace shaders
+}} // namespace mbgl
 
-    shader_lines = [("""    {{
-        R"{name}_vert({preamble}\n{vertex}){name}_vert",
-        R"{name}_frag({preamble}\n{fragment}){name}_frag",
-    }},
-""").format(
-    name = shader,
-    preamble = preamble,
-    vertex = shaders[shader]['vertex'],
-    fragment = shaders[shader]['fragment']
-) for shader in shaders]
-
-    source = """// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.
-#include <mbgl/platform/gl.hpp>
-{prefix}
-#include <mbgl/shader/shaders.hpp>
-
-namespace mbgl {{
-
-const shader_source shaders[SHADER_COUNT] = {{
-{shaders}
-}};
-
-}}
-{suffix}
+#endif
 """.format(
-    prefix = prefix,
-    suffix = suffix,
-    shaders = ''.join(shader_lines)
+     name = shader_name,
+     NAME = shader_name.upper(),
+     type = shader_type,
+     TYPE = shader_type.upper(),
+     data = data,
 )
 
-    source_path = os.path.join(output_dir, 'src/shader/shaders_' + shader_platform + '.cpp')
-    mkdir_p(os.path.dirname(source_path))
-    with open(source_path, 'w') as f: f.write(source)
-
-write_header()
-write_source('gl', '#ifndef GL_ES_VERSION_2_0', '#endif')
-write_source('gles2', '#ifdef GL_ES_VERSION_2_0', '#endif')
+mkdir_p(os.path.dirname(output_file))
+with open(output_file, 'w') as f: f.write(content)