FullscreenTriangle.hlsl

//	VQE
//	Copyright(C) 2020  - Volkan Ilbeyli
//
//	This program is free software : you can redistribute it and / or modify
//	it under the terms of the GNU General Public License as published by
//	the Free Software Foundation, either version 3 of the License, or
//	(at your option) any later version.
//
//	This program is distributed in the hope that it will be useful,
//	but WITHOUT ANY WARRANTY; without even the implied warranty of
//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
//	GNU General Public License for more details.
//
//	You should have received a copy of the GNU General Public License
//	along with this program.If not, see <http://www.gnu.org/licenses/>.
//
//	Contact: volkanilbeyli@gmail.com

Texture2D texSrc;
SamplerState Sampler;

struct PSInput
{
    float4 position : SV_POSITION;
	float2 uv       : TEXCOORD0;
};

PSInput VSMain(uint id : SV_VertexID)
{
    PSInput VSOut;

	// Fullscreen Triangle: https://rauwendaal.net/2014/06/14/rendering-a-screen-covering-triangle-in-opengl/
	//
	// V0.pos = (-1, -1) | V0.uv = (0,  1)
	// V1.pos = ( 3, -1) | V1.uv = (2,  1)
	// V2.pos = (-1,  3) | V2.uv = (0, -1)
	VSOut.position.x = -1.0f + (float)((id & 1) << 2);
	VSOut.position.y = -1.0f + (float)((id & 2) << 1);
	VSOut.uv[0]       = 0.0f + (float)((id & 1) << 1);
	VSOut.uv[1]       = 1.0f - (float)((id & 2) << 0);
	
	VSOut.position.z = 0.0f;
	VSOut.position.w = 1.0f;
	return VSOut;
}

float4 PSMain(PSInput input) : SV_TARGET
{
	return float4(texSrc.SampleLevel(Sampler, input.uv, 0).rgb, 1);
}