seems framebuffer buffer has different Y+ direction on metal and opengl

[lemoon]

i try to fill content to a framebuffer ,then present framebuffer to screen
for example ,i draw a full screen texture to a framebuffer,then draw framebuffer's color to the screen
it seems has different result on Metal/OpenGL backend, Screen result shows that will flip texture's Y-axis on OpenGL backend and looks good on Metal.

And how to solve this problem?

simple vs draw a full screen image

$input a_position,a_texcoord0
$output v_texcoord0

void main()
{
    gl_Position = vec4(a_position, 1.0);
    v_texcoord0 = a_texcoord0;
}

simple fs draw a full screen image

$input v_texcoord0
#include "../../../../core/shaders/common/common.sh"

SAMPLER2D(u_texture,0);


void main()
{
    gl_FragColor = texture2D(u_texture, v_texcoord0);
}

mesh data
float vertices[] =
{
x, y2, 0, 1,
x, y, 0, 0,
x2, y2, 1, 1,
x2, y, 1, 0
};

i think there are somthing bgfx need to do.
gpuweb/gpuweb#416

[bkaradzic]

You should check documentation and examples and you'll see how it's dealt with it... Search for originBottomLeft:
https://bkaradzic.github.io/bgfx/bgfx.html#_CPPv4N4bgfx4Caps16originBottomLeftE