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/raytracingreflections/closesthit.rchit

@@ -0,0 +1,76 @@
+#version 460
+#extension GL_EXT_ray_tracing : require
+#extension GL_EXT_nonuniform_qualifier : enable
+
+struct RayPayload {
+	vec3 color;
+	float distance;
+	vec3 normal;
+	float reflector;
+};
+
+layout(location = 0) rayPayloadInEXT RayPayload rayPayload;
+
+hitAttributeEXT vec3 attribs;
+
+layout(binding = 0, set = 0) uniform accelerationStructureEXT topLevelAS;
+layout(binding = 2, set = 0) uniform UBO 
+{
+	mat4 viewInverse;
+	mat4 projInverse;
+	vec4 lightPos;
+	int vertexSize;
+} ubo;
+layout(binding = 3, set = 0) buffer Vertices { vec4 v[]; } vertices;
+layout(binding = 4, set = 0) buffer Indices { uint i[]; } indices;
+
+struct Vertex
+{
+  vec3 pos;
+  vec3 normal;
+  vec2 uv;
+  vec4 color;
+  vec4 _pad0; 
+  vec4 _pad1;
+};
+
+Vertex unpack(uint index)
+{
+	// Unpack the vertices from the SSBO using the glTF vertex structure
+	// The multiplier is the size of the vertex divided by four float components (=16 bytes)
+	const int m = ubo.vertexSize / 16;
+
+	vec4 d0 = vertices.v[m * index + 0];
+	vec4 d1 = vertices.v[m * index + 1];
+	vec4 d2 = vertices.v[m * index + 2];
+
+	Vertex v;
+	v.pos = d0.xyz;
+	v.normal = vec3(d0.w, d1.x, d1.y);
+	v.color = vec4(d2.x, d2.y, d2.z, 1.0);
+
+	return v;
+}
+
+void main()
+{
+	ivec3 index = ivec3(indices.i[3 * gl_PrimitiveID], indices.i[3 * gl_PrimitiveID + 1], indices.i[3 * gl_PrimitiveID + 2]);
+
+	Vertex v0 = unpack(index.x);
+	Vertex v1 = unpack(index.y);
+	Vertex v2 = unpack(index.z);
+
+	// Interpolate normal
+	const vec3 barycentricCoords = vec3(1.0f - attribs.x - attribs.y, attribs.x, attribs.y);
+	vec3 normal = normalize(v0.normal * barycentricCoords.x + v1.normal * barycentricCoords.y + v2.normal * barycentricCoords.z);
+
+	// Basic lighting
+	vec3 lightVector = normalize(ubo.lightPos.xyz);
+	float dot_product = max(dot(lightVector, normal), 0.6);
+	rayPayload.color = v0.color.rgb * vec3(dot_product);
+	rayPayload.distance = gl_RayTmaxEXT;
+	rayPayload.normal = normal;
+
+	// Objects with full white vertex color are treated as reflectors
+	rayPayload.reflector = ((v0.color.r == 1.0f) && (v0.color.g == 1.0f) && (v0.color.b == 1.0f)) ? 1.0f : 0.0f; 
+}