OpenGL: Implement FXAA

src/video_core/host_shaders/fxaa.vert

@@ -0,0 +1,40 @@
+// Copyright 2019 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#version 460
+
+out gl_PerVertex {
+    vec4 gl_Position;
+};
+
+const vec2 vertices[4] =
+    vec2[4](vec2(-1.0, 1.0), vec2(1.0, 1.0), vec2(-1.0, -1.0), vec2(1.0, -1.0));
+
+layout (location = 0) out vec4 posPos;
+
+#ifdef VULKAN
+
+#define BINDING_COLOR_TEXTURE 1
+
+#else // ^^^ Vulkan ^^^ // vvv OpenGL vvv
+
+#define BINDING_COLOR_TEXTURE 0
+
+#endif
+
+layout (binding = BINDING_COLOR_TEXTURE) uniform sampler2D input_texture;
+
+const float FXAA_SUBPIX_SHIFT = 0;
+
+void main() {
+#ifdef VULKAN
+  vec2 vertex = vertices[gl_VertexIndex];
+#else
+  vec2 vertex = vertices[gl_VertexID];
+#endif
+  gl_Position = vec4(vertex, 0.0, 1.0);
+  vec2 vert_tex_coord = (vertex + 1.0) / 2.0;
+  posPos.xy = vert_tex_coord;
+  posPos.zw = vert_tex_coord - (0.5 + FXAA_SUBPIX_SHIFT) / textureSize(input_texture, 0);
+}