build: don't override glsl version, if possible

misc/glslc-test-uniform-location.frag.glsl

@@ -0,0 +1,13 @@
+#version 330 core
+#extension GL_ARB_explicit_uniform_location : require
+
+layout(location = 0) in vec2 texCoord;
+
+layout(location = 0) out vec4 outColor;
+
+layout(location = 0) uniform sampler2D tex;
+layout(location = 1) uniform vec4 color;
+
+void main(void) {
+    outColor = texture(tex, texCoord) * color;
+}

misc/meson.build

@@ -27,4 +27,5 @@ if angle_enabled and host_machine.system() == 'windows'
     bindist_deps += angle_bat
 endif
 
-glslc_test_file = files('glslc-test.frag.glsl')
+glslc_test_basic_file = files('glslc-test-basic.frag.glsl')
+glslc_test_uniform_location_file = files('glslc-test-uniform-location.frag.glsl')

resources/00-taisei.pkgdir/shader/lib/defs.glslh

@@ -6,6 +6,10 @@
     #extension GL_ARB_explicit_uniform_location : require
 #endif
 
+#if defined(SPIRV)
+	#extension GL_ARB_separate_shader_objects : require
+#endif
+
 #define LOC(l) layout(location = l)
 
 #if defined(GL_ARB_explicit_uniform_location) || __VERSION__ >= 430
@@ -14,7 +18,7 @@
     #define UNIFORM(l) uniform
 #endif
 
-#if __VERSION__ >= 420
+#if __VERSION__ >= 420 || defined(SPIRV)
     #define IN(l) LOC(l) in
     #define OUT(l) LOC(l) out
 #else

resources/00-taisei.pkgdir/shader/meson.build

@@ -100,15 +100,8 @@ essl_targets = []
 glslc_args = [
     # '-fauto-bind-uniforms',
     # '-fauto-map-locations',
-
-    # XXX: glslc currently doesn't support ARB_explicit_uniform_location, so we have
-    # to force a standard that supports it natively to check for location overlaps.
-    '-std=430core',
-
-    # TODO: somehow shut up that annoying warning caused by forcing glsl version.
-    # '-Werror',
-
     '--target-env=opengl',
+    '-DSPIRV',
 ]
 
 glslc_depfile_args = [
@@ -163,26 +156,43 @@ if validate_glsl != 'false'
 
     if not glslc_command.found() and validate_glsl == 'true'
         glslc_command = subproject('shaderc').get_variable('glslc_native')
+        glslc_args += '-Werror'
         validate_glsl = true
     elif glslc_command.found()
         test_result = run_command(glslc_command,
             glslc_args,
             glslc_frag_args,
-            glslc_test_file,
-            '-o',
-            join_paths(meson.build_root(), 'glslc-test.spv')
+            glslc_test_uniform_location_file,
+            '-o', '-',
+            capture : false
         )
 
         if test_result.returncode() == 0
+            glslc_args += '-Werror'
             validate_glsl = true
         else
-            warning(test_result.stderr())
+            glslc_args += '-std=430core'
+            warning('glslc does not support GL_ARB_explicit_uniform_location, forcing shader version to 430core as a workaround.\n\n@0@'.format(test_result.stderr()))
 
-            if validate_glsl == 'auto'
-                warning('glslc test failed, you probably have an incompatible version. GLSL validation will be disabled.')
-                validate_glsl = false
+            test_result = run_command(glslc_command,
+                glslc_args,
+                glslc_frag_args,
+                glslc_test_basic_file,
+                '-o', '-',
+                capture : false
+            )
+
+            if test_result.returncode() == 0
+                validate_glsl = true
             else
-                error('glslc test failed, you probably have an incompatible version.')
+                warning(test_result.stderr())
+
+                if validate_glsl == 'auto'
+                    warning('glslc test failed, you probably have an incompatible version. GLSL validation will be disabled.')
+                    validate_glsl = false
+                else
+                    error('glslc test failed, you probably have an incompatible version.')
+                endif
             endif
         endif
     else