Update ray tracing samples to use VK_KHR_ray_tracing (#753)

* Started updating ray tracing samples to KHR extension

* Updated GLSL shaders to use GL_EXT_ray_tracing

* Code cleanup, naming

* Fix include directories to use Vulkan headers from repository instead of NDK for the Android build

* Added new Android function pointers

* Renamed basic ray tracing sample

Added android build files

* Remove unused batch file

* Replaced remaining NV identifiers

* Updating ray tracing shadow sample to KHR extension

* Updated shaders to use KHR instead of NV extension

Fixed shader bindings

* Updating ray tracing reflections sample to KHR extension

* Renamed ray tracing reflections sample

* Renamed ray tracing shadows sample

Added android build files

* Removed no-longer used batch files for shader generation

* Proper alignment for the shader binding table

* Updated readme

* Reworked shader group setup

* Cleanup

* Reworked shader group setup

* Reworked shader group setup

* Code cleanup

data/shaders/glsl/raytracingbasic/closesthit.rchit

@@ -0,0 +1,12 @@
+#version 460
+#extension GL_EXT_ray_tracing : enable
+#extension GL_EXT_nonuniform_qualifier : enable
+
+layout(location = 0) rayPayloadInEXT vec3 hitValue;
+hitAttributeEXT vec3 attribs;
+
+void main()
+{
+  const vec3 barycentricCoords = vec3(1.0f - attribs.x - attribs.y, attribs.x, attribs.y);
+  hitValue = barycentricCoords;
+}

data/shaders/glsl/raytracingbasic/miss.rmiss

@@ -0,0 +1,9 @@
+#version 460
+#extension GL_EXT_ray_tracing : enable
+
+layout(location = 0) rayPayloadInEXT vec3 hitValue;
+
+void main()
+{
+    hitValue = vec3(0.0, 0.0, 0.2);
+}

data/shaders/glsl/raytracingbasic/raygen.rgen

@@ -0,0 +1,32 @@
+#version 460
+#extension GL_EXT_ray_tracing : enable
+
+layout(binding = 0, set = 0) uniform accelerationStructureEXT topLevelAS;
+layout(binding = 1, set = 0, rgba8) uniform image2D image;
+layout(binding = 2, set = 0) uniform CameraProperties 
+{
+	mat4 viewInverse;
+	mat4 projInverse;
+} cam;
+
+layout(location = 0) rayPayloadEXT vec3 hitValue;
+
+void main() 
+{
+	const vec2 pixelCenter = vec2(gl_LaunchIDEXT.xy) + vec2(0.5);
+	const vec2 inUV = pixelCenter/vec2(gl_LaunchSizeEXT.xy);
+	vec2 d = inUV * 2.0 - 1.0;
+
+	vec4 origin = cam.viewInverse * vec4(0,0,0,1);
+	vec4 target = cam.projInverse * vec4(d.x, d.y, 1, 1) ;
+	vec4 direction = cam.viewInverse*vec4(normalize(target.xyz), 0) ;
+
+	float tmin = 0.001;
+	float tmax = 10000.0;
+
+    hitValue = vec3(0.0);
+
+    traceRayEXT(topLevelAS, gl_RayFlagsOpaqueEXT, 0xff, 0, 0, 0, origin.xyz, tmin, direction.xyz, tmax, 0);
+
+	imageStore(image, ivec2(gl_LaunchIDEXT.xy), vec4(hitValue, 0.0));
+}