module evael.renderer.gl.gl_uniform_resource;

import evael.renderer.gl.gl_wrapper;
import evael.renderer.gl.gl_buffer;

import evael.renderer.resources.uniform_resource;

import evael.lib.memory : MemoryHelper;

private uint bindingPointIndex;

class GLUniformResource(T) : UniformResource!T
{   
    private uint m_blockIndex;
    private uint m_bindingPointIndex;

    /**
     * GLUniformResource constructor.
     */
    @nogc
    public this(in string name, in uint programId, T defaultValue)
    {
        super(name);

        assert(this.m_blockIndex != GL_INVALID_INDEX);

        this.m_buffer = MemoryHelper.create!UniformBuffer(T.sizeof, &defaultValue);
        this.m_blockIndex = gl.GetUniformBlockIndex(programId, cast(char*) this.m_name.ptr);
        this.m_bindingPointIndex = bindingPointIndex++;
        
        gl.BindBufferBase(GL_UNIFORM_BUFFER, this.m_bindingPointIndex, this.m_buffer.id);
        gl.UniformBlockBinding(programId, this.m_blockIndex, this.m_bindingPointIndex);

        gl.BindBuffer(GL_UNIFORM_BUFFER, 0);
    }

    @nogc
    public override void apply() const nothrow
    {
    }

    @nogc
    public override void clear() const nothrow
    {
    }

    @nogc
    public override void update() const nothrow
    {
        this.m_buffer.update(0, T.sizeof, &this.m_uniformStruct);
    }

    @nogc
    @property nothrow
    {
        public uint blockIndex() const
        {
            return this.m_blockIndex;
        }
    }
}