[vulkan] Point list rendering improvements

Implement register and vertex-shader-written point size. Fix point size
computation in geometry shader (convert pixel size to NDC scale using
viewport size). Fix point sprite coordinate generation.

src/xenia/gpu/vulkan/shaders/point_list.geom

@@ -4,23 +4,31 @@
 #version 450 core
 #extension all : warn
 
+layout(push_constant) uniform push_consts_type {
+  vec4 window_scale;
+  vec4 vtx_fmt;
+  vec4 point_size;
+  vec4 alpha_test;
+  uint ps_param_gen;
+} push_constants;
+
 in gl_PerVertex {
   vec4 gl_Position;
-  float gl_PointSize;
   // float gl_ClipDistance[];
 } gl_in[];
 
 out gl_PerVertex {
   vec4 gl_Position;
-  float gl_PointSize;
   // float gl_ClipDistance[];
 };
 
 layout(location = 0) in vec4 in_interpolators[][16];
-layout(location = 0) out vec4 out_interpolators[16];
+layout(location = 16) in vec2 in_point_coord_unused[];
+layout(location = 17) in float point_size[];
+
+layout(location = 0) out vec4 out_interpolators[16];
+layout(location = 16) out vec2 point_coord;
 
-// TODO(benvanik): fetch default point size from register and use that if
-//     the VS doesn't write oPointSize.
 // TODO(benvanik): clamp to min/max.
 // TODO(benvanik): figure out how to see which interpolator gets adjusted.
 
@@ -35,10 +43,17 @@ void main() {
     vec2( 1.0, -1.0),
   };
   vec4 pos = gl_in[0].gl_Position;
-  float psize = gl_in[0].gl_PointSize;
+  vec2 window_scaled_psize = push_constants.point_size.xy;
+  // Shader header writes -1.0f to pointSize by default, so any positive value
+  // means that it was overwritten by the translated vertex shader.
+  if (point_size[0] > 0.0f) {
+    window_scaled_psize = vec2(point_size[0]);
+  }
+  window_scaled_psize /= push_constants.window_scale.zw;
   for (int i = 0; i < 4; ++i) {
-    gl_Position = vec4(pos.xy + offsets[i] * psize, pos.zw);
+    gl_Position = vec4(pos.xy + (offsets[i] * window_scaled_psize), pos.zw);
     out_interpolators = in_interpolators[0];
+    point_coord = max(offsets[i], vec2(0.0f));
     EmitVertex();
   }
   EndPrimitive();