[dxvk] Add shaders for mip map generation

src/dxvk/shaders/dxvk_mipgen_frag_1d.frag

@@ -0,0 +1,11 @@
+#version 450
+
+layout(set = 0, binding = 0)
+uniform sampler1DArray s_texture;
+
+layout(location = 0) in  vec3 i_pos;
+layout(location = 0) out vec4 o_color;
+
+void main() {
+  o_color = texture(s_texture, i_pos.xz);
+}

src/dxvk/shaders/dxvk_mipgen_frag_2d.frag

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+#version 450
+
+layout(set = 0, binding = 0)
+uniform sampler2DArray s_texture;
+
+layout(location = 0) in  vec3 i_pos;
+layout(location = 0) out vec4 o_color;
+
+void main() {
+  o_color = texture(s_texture, i_pos);
+}

src/dxvk/shaders/dxvk_mipgen_frag_3d.frag

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+#version 450
+
+layout(set = 0, binding = 0)
+uniform sampler3D s_texture;
+
+layout(location = 0) in  vec3 i_pos;
+layout(location = 0) out vec4 o_color;
+
+layout(push_constant)
+uniform push_block {
+  uint p_layer_count;
+};
+
+void main() {
+  o_color = texture(s_texture, vec3(i_pos.xy,
+    (i_pos.z + 0.5f) / float(p_layer_count)));
+}

src/dxvk/shaders/dxvk_mipgen_geom.geom

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+#version 450
+
+layout(points) in;
+layout(triangle_strip, max_vertices = 4) out;
+
+layout(location = 0) in  int  i_instance[1];
+layout(location = 0) out vec3 o_pos;
+
+const vec4 g_vpos[4] = {
+  vec4(-1.0f, -1.0f, 0.0f, 1.0f),
+  vec4(-1.0f,  1.0f, 0.0f, 1.0f),
+  vec4( 1.0f, -1.0f, 0.0f, 1.0f),
+  vec4( 1.0f,  1.0f, 0.0f, 1.0f),
+};
+
+void main() {
+  for (int i = 0; i < 4; i++) {
+    o_pos       = vec3(0.5f + 0.5f * g_vpos[i].xy, float(i_instance[0]));
+    gl_Position = g_vpos[i];
+    gl_Layer    = i_instance[0];
+    EmitVertex();
+  }
+  
+  EndPrimitive();
+}

src/dxvk/shaders/dxvk_mipgen_vert.vert

@@ -0,0 +1,8 @@
+#version 450
+
+layout(location = 0) out int o_instance;
+
+void main() {
+  o_instance = gl_InstanceIndex;
+  gl_Position = vec4(0.0f, 0.0f, 0.0f, 1.0f);
+}