How to use opengl es 3.2 in Windows - vulkan backend

[王正森]

On windows, I have followed the steps at https://chromium.googlesource.com/angle/angle/+/HEAD/doc/DevSetup.md to successfully compile angle (using a vulkan backend).

Here are my compilation options:

```
is_component_build = false
target_cpu = ‘x64’
is_debug = false
angle_assert_always_on = false
is_clang = true

angle_enable_d3d9 = false
angle_enable_d3d11 = false
angle_enable_gl = false
angle_enable_metal = false
angle_enable_null = false
angle_enable_vulkan = true
angle_enable_glsl = true
```

I successfully create the window and gl context using glfw, but the version of gles I get is not gles3.2, but gles3.1:.

```
    ::glfwInitHint(GLFW_ANGLE_PLATFORM_TYPE, GLFW_ANGLE_PLATFORM_TYPE_VULKAN);
    ::glfwInit();
    ::glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
    ::glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_EGL_CONTEXT_API); 
    ::glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    ::glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0); .
``

Here is the version output:

OpenGL ES 3.1.0 (ANGLE 2.1.24553 git hash: bb6400198da7)

I am not an expert in ANGLE or VULKAN, I hope I can get help here, thanks.

[Shahbaz Youssefi]

Hello,

Assuming you are using tip-of-tree of ANGLE, this is an indication that your system is missing a feature that would allow ANGLE to expose GLES3.2. If you step through the `Renderer::getMaxSupportedESVersion()` function, it would tell you why ANGLE had to drop to GLES3.1.

What is your GPU / driver version?