Added KRShaderManager::Includer

Now able to include shaders from other shaders with GL_GOOGLE_include_directive.
Added vulkan_test_include.glsl and included it from vulkan_test.vert.

standard_assets/shaders/CMakeLists.txt

@@ -7,3 +7,4 @@ add_standard_asset(vulkan_test.vert)
 add_standard_asset(vulkan_test.frag)
 add_standard_asset(debug_font.vert)
 add_standard_asset(debug_font.frag)
+add_standard_asset(vulkan_test_include.glsl)

standard_assets/shaders/vulkan_test.vert

@@ -1,4 +1,7 @@
 #version 450
+#extension GL_GOOGLE_include_directive : enable
+
+#include "vulkan_test_include.glsl"
 
 // Temporary test shader for vulkan bringup...
 // See https://vulkan-tutorial.com/Drawing_a_triangle/Graphics_pipeline_basics/Shader_modules
@@ -17,5 +20,5 @@ layout( push_constant ) uniform constants
 
 void main() {
     gl_Position = vec4(vertex_position * 0.5, 1.0);
-    fragColor = vertex_normal * 0.25 + vec3(0.5, 0.5, 0.5);
+    fragColor = vertex_normal * 0.25 + vec3(0.5, 0.5, 0.5) * VULKAN_TEST_BRIGHTNESS;
 }

standard_assets/shaders/vulkan_test_include.glsl

@@ -0,0 +1,2 @@
+
+#define VULKAN_TEST_BRIGHTNESS 0.25