Is it possible to write new SpriteBatch.Begin function?

Question

I am creating a game with an isometric view. I have a structure which is currently working quite effectively, using two matrices. This requires additional members and functions that I would like to do without, though. One of the SpriteBatch.Begin functions accepts a transformation matrix as a parameter. I would like to write a new SpriteBatch.Begin function to accept two matrices (one for camera transformation, and one for isometric transformation). I don't know how the actual SpriteBatch.Begin function works, and I don't know if there is any source available. Does anyone have an idea?

Answer 1

Ok, after the edit I searched for the source code for the SpriteBatch.begin() function. I found the source code for monogame which is an open-source implementation of XNA.

So here it is:

using System;
using System.Text;

namespace Microsoft.Xna.Framework.Graphics
{
    public class SpriteBatch : GraphicsResource
    {
        readonly SpriteBatcher _batcher;

            SpriteSortMode _sortMode;
            BlendState _blendState;
            SamplerState _samplerState;
            DepthStencilState _depthStencilState; 
            RasterizerState _rasterizerState;                
            Effect _effect;
            bool _beginCalled;

            Effect _spriteEffect;
            readonly EffectParameter _matrixTransform;
            readonly EffectPass _spritePass;

            Matrix _matrix;
            Rectangle _tempRect = new Rectangle (0,0,0,0);
            Vector2 _texCoordTL = new Vector2 (0,0);
            Vector2 _texCoordBR = new Vector2 (0,0);

            public SpriteBatch (GraphicsDevice graphicsDevice)
            {
                if (graphicsDevice == null) 
                {
                        throw new ArgumentException ("graphicsDevice");
                }        

                this.GraphicsDevice = graphicsDevice;

                // Use a custom SpriteEffect so we can control the transformation matrix
                _spriteEffect = new Effect(graphicsDevice, SpriteEffect.Bytecode);
                _matrixTransform = _spriteEffect.Parameters["MatrixTransform"];
                _spritePass = _spriteEffect.CurrentTechnique.Passes[0];

                _batcher = new SpriteBatcher(graphicsDevice);

                _beginCalled = false;
            }

            public void Begin ()
            {
                Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.LinearClamp, DepthStencilState.None, RasterizerState.CullCounterClockwise, null, Matrix.Identity);        
            }

            public void Begin (SpriteSortMode sortMode, BlendState blendState, SamplerState samplerState, DepthStencilState depthStencilState, RasterizerState rasterizerState, Effect effect, Matrix transformMatrix)
            {
                if (_beginCalled)
                    throw new InvalidOperationException("Begin cannot be called again until End has been successfully called.");

                // defaults
                _sortMode = sortMode;
                _blendState = blendState ?? BlendState.AlphaBlend;
                _samplerState = samplerState ?? SamplerState.LinearClamp;
                _depthStencilState = depthStencilState ?? DepthStencilState.None;
                _rasterizerState = rasterizerState ??   RasterizerState.CullCounterClockwise;

                _effect = effect;

                _matrix = transformMatrix;

                // Setup things now so a user can chage them.
                if (sortMode == SpriteSortMode.Immediate)
                    Setup();

                _beginCalled = true;
            }

            public void Begin (SpriteSortMode sortMode, BlendState blendState)
            {
                Begin (sortMode, blendState, SamplerState.LinearClamp, DepthStencilState.None, RasterizerState.CullCounterClockwise, null, Matrix.Identity);                        
            }

            public void Begin (SpriteSortMode sortMode, BlendState blendState, SamplerState samplerState, DepthStencilState depthStencilState, RasterizerState rasterizerState)
            {
                Begin (sortMode, blendState, samplerState, depthStencilState, rasterizerState, null, Matrix.Identity);        
            }

            public void Begin (SpriteSortMode sortMode, BlendState blendState, SamplerState samplerState, DepthStencilState depthStencilState, RasterizerState rasterizerState, Effect effect)
            {
                Begin (sortMode, blendState, samplerState, depthStencilState, rasterizerState, effect, Matrix.Identity);                        
            }

            public void End ()
            {        
                _beginCalled = false;

                if (_sortMode != SpriteSortMode.Immediate)
                        Setup();

#if PSM   
        GraphicsDevice.BlendState = _blendState;
        _blendState.ApplyState(GraphicsDevice);
#endif

        _batcher.DrawBatch(_sortMode);
    }

The file is not complete, i didn't paste after the end function but if you want to read the entire file. The link is : https://github.com/mono/MonoGame/blob/7ec1ec8a0e924eca60588e770121ed3e2593e74d/MonoGame.Framework/Graphics/SpriteBatch.cs

I hope this was the source code you were looking for.

Good luck!

This is my other answer:

You need to call spriteBatch.Begin() and spriteBatch.End() in your main Draw() function so you can actually draw.

Here is an example:

The Draw() function in Game1.cs :

protected override void Draw(GameTime gameTime)
{
    GraphicsDevice.Clear(Color.CornflowerBlue);

    // Start drawing
    spriteBatch.Begin();

    player.Draw(spriteBatch);

    // Stop drawing
    spriteBatch.End();

    base.Draw(gameTime);
}

The Draw() function in Player.cs :

public void Draw(SpriteBatch spriteBatch)
{
    spriteBatch.Draw(playerTexture, playerPosition, null, Color.White, 0f, Vector2.Zero, 1f, SpriteEffects.None, 1f);
}

This will draw the player to the screen with the Draw() function out of Player.cs . The spriteBatch is initialized in the LoadContent() function of Game1.cs .

I hope this Helps!

Answer 2

You can create your own "Draw" for objects and call them from within the "Draw" of "Game1.cs".

Example:

protected override void Draw(GameTime gameTime){

myObject.Draw(gameTime);

}

Hope this help !