[[vertex]]

uniform mat4 mvp;

in vec4 pos;
in vec2 uvs;
out vec2 uv;

void main()
{
    uv = uvs;
    gl_Position = mvp * vec4(pos.xyz, 1.0);
}

[[fragment]]

#include "include/ext-fb-fetch.glsl"
#include "include/blend.glsl"

uniform sampler2D tex;
uniform sampler2D tex_bg;
uniform highp float alpha;
uniform int blend_mode;

in highp vec2 uv;
#if defined(GL_EXT_shader_framebuffer_fetch)
    inout highp vec4 frag;
#else
    out highp vec4 frag;
#endif

void main()
{
    // if available use the extension
#if defined(GL_EXT_shader_framebuffer_fetch)
    highp vec4 bg = frag;
#elif defined(GL_ARM_shader_framebuffer_fetch)
    highp vec4 bg = gl_LastFragColorARM;
#else
    highp vec4 bg = texture(tex_bg, uv);
#endif

    highp vec4 fg = texture(tex, uv);
    if (fg.a == 0.0)
    {
        frag = bg;
        return;
    }
    highp vec4 blended = blend(bg, fg, blend_mode);
    frag = vec4(blended.rgb, blended.a * alpha);
}