Move shaders into glsl and hlsl directories

Move `data/shaders` to `data/shaders/glsl`
Move `data/hlsl` to `data/shaders/hlsl`

Fix up shader paths in the cpp files to point to the new glsl location.

`data/shaders/hlsl/compile.py` still overwrites the glsl .spv files (for
now).

Issue: #723

data/shaders/glsl/multithreading/generate-spirv.bat

@@ -0,0 +1,4 @@
+glslangvalidator -V phong.vert -o phong.vert.spv
+glslangvalidator -V phong.frag -o phong.frag.spv
+glslangvalidator -V starsphere.vert -o starsphere.vert.spv
+glslangvalidator -V starsphere.frag -o starsphere.frag.spv

data/shaders/glsl/multithreading/phong.frag

@@ -0,0 +1,20 @@
+#version 450
+
+layout (location = 0) in vec3 inNormal;
+layout (location = 1) in vec3 inColor;
+layout (location = 3) in vec3 inViewVec;
+layout (location = 4) in vec3 inLightVec;
+
+layout (location = 0) out vec4 outFragColor;
+
+
+void main() 
+{
+	vec3 N = normalize(inNormal);
+	vec3 L = normalize(inLightVec);
+	vec3 V = normalize(inViewVec);
+	vec3 R = reflect(-L, N);
+	vec3 diffuse = max(dot(N, L), 0.0) * inColor;
+	vec3 specular = pow(max(dot(R, V), 0.0), 8.0) * vec3(0.75);
+	outFragColor = vec4(diffuse + specular, 1.0);	
+}

data/shaders/glsl/multithreading/phong.vert

@@ -0,0 +1,39 @@
+#version 450
+
+layout (location = 0) in vec3 inPos;
+layout (location = 1) in vec3 inNormal;
+layout (location = 2) in vec3 inColor;
+
+layout (std140, push_constant) uniform PushConsts 
+{
+	mat4 mvp;
+	vec3 color;
+} pushConsts;
+
+layout (location = 0) out vec3 outNormal;
+layout (location = 1) out vec3 outColor;
+layout (location = 3) out vec3 outViewVec;
+layout (location = 4) out vec3 outLightVec;
+
+void main() 
+{
+	outNormal = inNormal;
+
+	if ( (inColor.r == 1.0) && (inColor.g == 0.0) && (inColor.b == 0.0))
+	{	
+		outColor = pushConsts.color;
+	}
+	else
+	{
+		outColor = inColor;
+	}
+	
+	gl_Position = pushConsts.mvp * vec4(inPos.xyz, 1.0);
+	
+    vec4 pos = pushConsts.mvp * vec4(inPos, 1.0);
+    outNormal = mat3(pushConsts.mvp) * inNormal;
+//	vec3 lPos = ubo.lightPos.xyz;
+vec3 lPos = vec3(0.0);
+    outLightVec = lPos - pos.xyz;
+    outViewVec = -pos.xyz;
+}

data/shaders/glsl/multithreading/starsphere.frag

@@ -0,0 +1,39 @@
+#version 450
+
+layout (location = 0) in vec3 inUVW;
+
+layout (location = 0) out vec4 outFragColor;
+
+#define HASHSCALE3 vec3(443.897, 441.423, 437.195)
+#define STARFREQUENCY 0.01
+
+// Hash function by Dave Hoskins (https://www.shadertoy.com/view/4djSRW)
+float hash33(vec3 p3)
+{
+	p3 = fract(p3 * HASHSCALE3);
+    p3 += dot(p3, p3.yxz+vec3(19.19));
+    return fract((p3.x + p3.y)*p3.z + (p3.x+p3.z)*p3.y + (p3.y+p3.z)*p3.x);
+}
+
+vec3 starField(vec3 pos)
+{
+	vec3 color = vec3(0.0);
+    float threshhold = (1.0 - STARFREQUENCY);
+    float rnd = hash33(pos);
+    if (rnd >= threshhold)
+    {
+        float starCol = pow((rnd - threshhold) / (1.0 - threshhold), 16.0);
+		color += vec3(starCol);
+    }	
+	return color;
+}
+
+void main() 
+{
+	// Fake atmosphere at the bottom
+	vec3 atmosphere = clamp(vec3(0.1, 0.15, 0.4) * (inUVW.t - 5.0), 0.0, 1.0);
+
+	vec3 color = starField(inUVW) + atmosphere;
+	
+	outFragColor = vec4(color, 1.0);
+}

data/shaders/glsl/multithreading/starsphere.vert

@@ -0,0 +1,16 @@
+#version 450
+
+layout (location = 0) in vec3 inPos;
+
+layout (std140, push_constant) uniform PushConsts 
+{
+	mat4 mvp;
+} pushConsts;
+
+layout (location = 0) out vec3 outUVW;
+
+void main() 
+{
+	outUVW = inPos;
+	gl_Position = pushConsts.mvp * vec4(inPos.xyz, 1.0);
+}