#include "shaders/common.hlsl"

struct vs_instance {
    float2x3 xf;
};

struct ps_input {
    DESV(float4, screen_pos, SV_POSITION);
};

/* ========================== *
 * Globals
 * ========================== */

StructuredBuffer<vs_instance> g_instance_buffer : register(t0);

cbuffer constants : register(b0)
{
    float4x4 g_projection;
    uint g_instance_offset;
};

/* ========================== *
 * Vertex shader
 * ========================== */

static const float2 G_quad_verts[4] = {
    float2(-0.5f, -0.5f),
    float2( 0.5f, -0.5f),
    float2( 0.5f,  0.5f),
    float2(-0.5f,  0.5f)
};

ps_input vs_main(uint instance_id : SV_InstanceID, uint vertex_id : SV_VertexID)
{
    vs_instance instance = g_instance_buffer[g_instance_offset + instance_id];
    float2 vert = G_quad_verts[vertex_id];
    float2 world_pos = mul(instance.xf, float3(vert, 1)).xy;
    ps_input output;
    output.screen_pos = mul(g_projection, float4(world_pos, 0, 1));
    return output;
}

/* ========================== *
 * Pixel shader
 * ========================== */

float4 ps_main(ps_input input) : SV_TARGET
{   
    return float4(0, 0, 0, 0);
}