C# HLSL/XNA/MonoGame Problems

Question

First of all, im new to shaders and xna.

I've been trying to follow this tutorial: http://www.xnahub.com/simple-2d-lighting-system-in-c-and-monogame/

I've done everything he said, I even ended up copy/pasting some parts to be totally sure although – it still won't work.

    sampler s0;
    texture lightMask;
    sampler lightSampler=sampler_state {
      Texture=<lightMask>;
    }
    ;
    float4 PixelShaderLight(float2 coords:TEXCOORD0):COLOR0 {
      float4 color=tex2D(s0, coords);
      float4 lightColor=tex2D(lightSampler, coords);
      return color * lightColor;
    }
    technique Technique1 {
      pass P0 {
        PixelShader=compile ps_4_0_level_9_1 PixelShaderLight();
      }
    }

The problem is that when I apply the pass 0 everything goes black.

My guess is that the lightcolor is returning zero. The lightmask is a renderTarget where I've painted my lights on.

I really dont know why lightcolor would return zero. If that is the case, could anyone give me a hint in what I'm doing wrong?

Here is my main class if you want to look at it:

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;

namespace TestingGame
{
    public class TestingGame : Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;
        Location loc;

        public static Texture2D lightMask;
        public static Texture2D img;
        public static Effect effect1;
        RenderTarget2D lightsTarget;
        RenderTarget2D mainTarget;

        public TestingGame()
        {
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";
        }

        protected override void Initialize()
        {
            loc = new Location(20,20);

            var pp = GraphicsDevice.PresentationParameters;
            lightsTarget = new RenderTarget2D(
            GraphicsDevice, pp.BackBufferWidth, pp.BackBufferHeight);
            mainTarget = new RenderTarget2D(
            GraphicsDevice, pp.BackBufferWidth, pp.BackBufferHeight);

            base.Initialize();
        }

        protected override void LoadContent()
        {

            spriteBatch = new SpriteBatch(GraphicsDevice);

            lightMask = Content.Load<Texture2D>("lightmask.png");
            img = Content.Load<Texture2D>("img.png");
            effect1 = Content.Load<Effect>("lighteffect");

        }

        protected override void UnloadContent()
        {
        }

        protected override void Update(GameTime gameTime)
        {
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed || Keyboard.GetState().IsKeyDown(Keys.Escape))
                Exit();
            if(loc.Equals(new Location(21,20)))
                System.Console.WriteLine("Working");
            base.Update(gameTime);
        }

        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.SetRenderTarget(lightsTarget);
            GraphicsDevice.Clear(Color.Black);
            spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.Additive);

            spriteBatch.Draw(lightMask, new Vector2(20, 20), Color.Red);

            spriteBatch.End();

            GraphicsDevice.SetRenderTarget(mainTarget);
            GraphicsDevice.Clear(Color.Transparent);
            spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend);

            spriteBatch.Draw(img, new Vector2(50,50));

            spriteBatch.End();

            GraphicsDevice.SetRenderTarget(null);
            GraphicsDevice.Clear(Color.Black);

            spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend);

            effect1.Parameters["lightMask"].SetValue(lightsTarget);
            effect1.CurrentTechnique.Passes[0].Apply();
            spriteBatch.Draw(mainTarget, Vector2.Zero, Color.White);

            spriteBatch.End();

            base.Draw(gameTime);
        }
    }
}

I too have tried my hand in writing Shaders in monogame, and like you, event when I copy-paste shaders from a tutorial (that is showing a positive result), they still end up doing nothing, or indeed turning the entire game black. Why that is, I really can't say. — Falgantil, Sep 03 '15 at 09:22
What's that `sampler s0;` in your shader? It's not defined and I can't see where you pass a parameter `s0` to the shader from your game. So I think the line `float4 color=tex2D(s0, coords);` will return black. — LInsoDeTeh, Sep 03 '15 at 12:05
I solved it, i think s0 is automatically set to the drawn texture i think. I think the problem was that i needed to add (position : SV_Position) to the constructor — Voxed, Sep 03 '15 at 17:32

score 0 · Answer 1 · answered Oct 10 '16 at 13:37

For the others like me who stumble upon this problem, you need to use the complete signature for the pixel shader as stated here : http://www.software7.com/blog/pitfalls-when-developing-hlsl-shader/

So the correct code for this shader is the following :

sampler s0;
texture lightMask;
sampler lightSampler=sampler_state {
  Texture=<lightMask>;
};

float4 PixelShaderLight(float4 pos: SV_POSITION, float4 color: COLOR0, float2 coords: TEXCOORD0): SV_TARGET0 {
  float4 color=tex2D(s0, coords);
  float4 lightColor=tex2D(lightSampler, coords);
  return color * lightColor;
}
technique Technique1 {
  pass P0 {
    PixelShader=compile ps_4_0_level_9_1 PixelShaderLight();
  }
}

C# HLSL/XNA/MonoGame Problems

1 Answers1