gl_state: Implement PROGRAM_POINT_SIZE

For gl_PointSize to have effect we have to activate
GL_PROGRAM_POINT_SIZE.

src/video_core/engines/maxwell_3d.h

@@ -1018,7 +1018,14 @@ public:
                     }
                 } instanced_arrays;
 
-                INSERT_UNION_PADDING_WORDS(0x6);
+                INSERT_UNION_PADDING_WORDS(0x4);
+
+                union {
+                    BitField<0, 1, u32> enable;
+                    BitField<4, 8, u32> unk4;
+                } vp_point_size;
+
+                INSERT_UNION_PADDING_WORDS(1);
 
                 Cull cull;
 
@@ -1503,6 +1510,7 @@ ASSERT_REG_POSITION(primitive_restart, 0x591);
 ASSERT_REG_POSITION(index_array, 0x5F2);
 ASSERT_REG_POSITION(polygon_offset_clamp, 0x61F);
 ASSERT_REG_POSITION(instanced_arrays, 0x620);
+ASSERT_REG_POSITION(vp_point_size, 0x644);
 ASSERT_REG_POSITION(cull, 0x646);
 ASSERT_REG_POSITION(pixel_center_integer, 0x649);
 ASSERT_REG_POSITION(viewport_transform_enabled, 0x64B);

src/video_core/renderer_opengl/gl_rasterizer.cpp

@@ -1272,6 +1272,7 @@ void RasterizerOpenGL::SyncPointState() {
     const auto& regs = system.GPU().Maxwell3D().regs;
     // Limit the point size to 1 since nouveau sometimes sets a point size of 0 (and that's invalid
     // in OpenGL).
+    state.point.program_control = regs.vp_point_size.enable ? GL_TRUE : GL_FALSE;
     state.point.size = std::max(1.0f, regs.point_size);
 }
 

src/video_core/renderer_opengl/gl_state.cpp

@@ -127,6 +127,7 @@ void OpenGLState::ApplyClipDistances() {
 }
 
 void OpenGLState::ApplyPointSize() {
+    Enable(GL_PROGRAM_POINT_SIZE, cur_state.point.program_control, point.program_control);
     if (UpdateValue(cur_state.point.size, point.size)) {
         glPointSize(point.size);
     }

src/video_core/renderer_opengl/gl_state.h

@@ -131,7 +131,8 @@ public:
     std::array<Viewport, Tegra::Engines::Maxwell3D::Regs::NumViewports> viewports;
 
     struct {
-        float size = 1.0f; // GL_POINT_SIZE
+        GLboolean program_control = GL_FALSE; // GL_PROGRAM_POINT_SIZE
+        GLfloat size = 1.0f;                  // GL_POINT_SIZE
     } point;
 
     struct {