Issues with drawing to alternative RenderTarget2D, seems to draw to backbuffer - c#

So in order to get the Color[] data from a texture after it has been rotated in order to use this data for perpixel collisions, I use the following method to draw said texture (rotated) to a separate RenderTarget2D, then convert this back into a texture2D and get the color data from it:
public Color[] GetColorDataOf(SpriteBatch spriteBatch, Texture2D texture, float rotation)
{
// Get boundingBox of texture after rotation
Rectangle boundingBox = GetEnclosingBoundingBox(texture, rotation);
// Create new rendertarget of this size
RenderTarget2D buffer = new RenderTarget2D(GraphicsDevice, boundingBox.Width, boundingBox.Height);
// Change spritebatch to new rendertarget
GraphicsDevice.SetRenderTarget(buffer);
// Clear new rendertarget
GraphicsDevice.Clear(Color.Transparent);
// Draw sprite to new rendertarget
spriteBatch.Draw(texture, new Rectangle(boundingBox.Width / 2, boundingBox.Height / 2, texture.Width, texture.Height), null, Color.White, rotation, new Vector2(boundingBox.Center.X, boundingBox.Center.Y), SpriteEffects.None, 1f);
// Change rendertarget back to backbuffer
GraphicsDevice.SetRenderTarget(null);
// Get color data from the rendertarger
Color[] colorData = new Color[boundingBox.Width * boundingBox.Height];
Texture2D bufferTexture = (Texture2D)buffer;
bufferTexture.GetData(colorData);
return colorData;
}
Now I'm having two issues with that (I expect they are linked), firstly the texture gets drawn on screen, and all the Color[] data returned is empty (i.e all fields equal to 0).
** Edit **
Using Texture2D.SaveAsPng() I can see that bufferTexture is the correct size but just completely transparent indicating that the issue would lie in drawing to the buffer.

So I fixed it. Turns out I need to create another set of SpriteBatch.Begin() and SpriteBatch.End() calls around where I drew to the new rendertargets, otherwise it was just drawing to the backbuffer instead.

Related

C# XNA - Start draw from bottom-center

Normally XNA start drawing sprite from top-left, but I would like to start draw object from bottom-center, how this could be done?
You want to specify a different origin in your SpriteBatch.Draw calls. The default is 0,0 (top-left). Note that the origin is relative to the sprite, not the screen.
So if your sprite is 64x64, you want to use an origin of 32x64 for bottom center.
e.g. using this override (MSDN)
spriteBatch.Draw (
texture,
position,
sourceRectangle,
color,
rotation,
new Vector2(32, 64), // origin
scale,
effects,
layerDepth
)
You can calculate these on the fly if you wish. e.g if you're using the full texture you could specify it as new Vector2(texture.Center.X, texture.Height). Or alternatively you could base it on the sourceRectangle if you're using a sprite sheet.
You need to specify a bunch of other arguments to use these Draw overrides but you can just pass in the defaults. The defaults are:
sourceRectangle: null = full texture
color: Color.White = default color (sprite colors will be used)
rotation: 0f = no rotation
scale: 1f = default scale
efects: SpriteEffects.None = no flipping
layerDepth: 0 = default layer
Lets say you are drawing an image WidthxHeight on position XxY.
spriteBatch.Draw(texture, position, Color.White);
First let's set the bottom of the image to those coordinates by subtracting images height from position's Y coordinate (subtracting because in XNA the Y-axis is inverted, not like in your math class)
spriteBatch.Draw(texture, position + new Vector2(0, -texture.Height), Color.White);
Second, let's set the image to the left by subtracting half of the image's width from position's X coordinate.
spriteBatch.Draw(texture, position + new Vector2(-texture.Width/2, -texture.Height), Color.White);
And there you have it.
Edit: Another thought: you can create new variable called DrawPosition and use that variable when needed, instead of always substracting. That would look something like this:
private Texture2D texture;
public Vector2 position;
public Vector2 DrawPosition
{ get { return position + new Vector2(-texture.Width/2, -texture.Height); } }
public void Draw(SpriteBatch spriteBatch)
{ spriteBatch.Draw(texture, DrawPosition, Color.White); }
Or, if this new variable doesn't make sense to you, create a function that will return the DrawPosition()
public Vector2 DrawPosition()
{ return position + new Vector2(-texture.Width/2, -texture.Height); }

My texture's transparency is shown black

I am trying to draw an image on to the screen. My image is drawn correctly but the background color which is transparent is shown black.
Why is this so?
My Code:
spriteBatch.Draw(Texture, Position + origin, SourceRect, Color.White * Alpha, 0.0f, origin, Scale, SpriteEffects.None, 0.0f);
Have a look at the Begin method of the SpriteBatch class:
https://msdn.microsoft.com/en-us/library/microsoft.xna.framework.graphics.spritebatch.begin.aspx
It is possible you set the BlendState to something that would ignore the alpha value of the texture.
To check if the Content Processor correctly imports the alpha values of your texture, try to run this code, the pixel at 0, 0 being a transparent pixel:
Color[] tData = null;
texture.GetData<Color>(tData);
Debug.Print(tData[0].ToString());
texture being the Texture2D you loaded from a ContentManager.

Drawing sprites to a permanent Texture2d using Monogame / XNA

(Cross post from Gamedevs)
I'm working with Monogame to do a 2d sprite engine. I've gotten it work pretty well where I can move lots of sprites around the screen with the effects and positions that I want.
Last night I tried to add a feature and I can't quite get it to work right.
I'm trying to create permanent trails that the moving sprites can leave behind. So I have a mostly transparent PNG with some white lines on it called "streak". The idea is that I set up a new Texture2D surface (called streakoverlay) and I draw the streaks on to it.
I switch back to the back buffer and draw: The background, the streakoverlay, and finally the sprite on top of it. The streaks should build up over time. It almost works, but the trouble I have is that streakOverlay seems to clear itself every time. How I'd like it to behave would be the same behaviour as having the graphics display without this line GraphicsDevice.Clear(Color.White); - everything would just pile up in it.
Instead it resets back to the Purple transparent color that is the default for that texture. Any suggestions? Here's the core piece of the rendering engine:
GraphicsDeviceManager graphics;
RenderTarget2D streakOverlay;
SpriteBatch spriteBatch;
private Texture2D bkg;
private Texture2D prototype;
private Texture2D streak;
//Initialize
graphics = new GraphicsDeviceManager(this);
GraphicsDevice.Clear(Color.Transparent);
streakOverlay = new RenderTarget2D(GraphicsDevice, 200,200);
//Load Content
bkg = Content.Load<Texture2D>("bkg"); //Background image
prototype = Content.Load<Texture2D>("prototype"); //Prototype sprite that moves around
streak = Content.Load<Texture2D>("blueStreak"); //Trails being left by Prototype sprite
graphics.GraphicsDevice.SetRenderTarget(streakOverlay);
GraphicsDevice.Clear(Color.Transparent); //Attempt to make the streakoverlay is fully transparent.
graphics.GraphicsDevice.SetRenderTarget(null);
//Draw
Random r = new Random();
graphics.GraphicsDevice.SetRenderTarget(streakOverlay); //Switch to drawing to the streakoverlay
spriteBatch.Begin();
//Draw some streaks that should accumulate
spriteBatch.Draw(streak, new Vector2(r.Next(0, 200), r.Next(0, 200)), null, Color.White, 0f, new Vector2(25, 25), 1f, SpriteEffects.None, 1f);
spriteBatch.End();
//Switch back to drawing on the back buffer.
graphics.GraphicsDevice.SetRenderTarget(null);
spriteBatch.Begin();
spriteBatch.Draw(bkg, new Rectangle(0, 0, 2000, 2000), Color.White); //Draw our background
spriteBatch.Draw(streakOverlay, new Vector2(0, 0), Color.White); //Put the overlay on top of it
spriteBatch.Draw(prototype, new Vector2(_spritePrototype.getX, _spritePrototype.getY), null, Color.White, DegreeToRadian(rotationSprite), new Vector2(25, 25), .5f, SpriteEffects.None, 0f); //Draw the sprite that's moving around.
spriteBatch.End();
base.Draw(gameTime);
You need to use the extended constructor for RenderTarget2D that takes 4 parameters and specify PreserveContents. The assumption is that render targets are often reused and so when it is set it gets cleared automatically unless this flag is set.

XNA Texture2D Billboarding appears as a white block

Very odd problem, when I try and draw my billboard sprite it always appears as a white block, changing the .draw color property still draws it as white, it also doesn't matter it I use a jpeg, or transparent png.
[EDIT]
So I'm now trying to use a Viewport instead of a basic effect to just get an x and y screen coordinate, I'll fix any scaling issue later, however now the image stays in the exact same spot (on the screen, it doesn't change position based on the camera) and doesn't get any bigger or smaller based on how far away it is
My new billboard rendering function:
public void Draw(Camera camera, GraphicsDevice device, SpriteBatch spriteBatch, Texture2D Texture)
{
Viewport viewport = new Viewport(new Rectangle(0, 0, 800, 480));
Vector3 viewSpaceTextPosition = viewport.Project(this.position, camera.Projection, camera.View, camera.World);
spriteBatch.Begin();
spriteBatch.Draw(Texture, new Vector2(viewSpaceTextPosition.X, viewSpaceTextPosition.Y), null, Color.White, 0, new Vector2(Texture.Bounds.Center.X, Texture.Bounds.Center.Y), this.Scale, SpriteEffects.None, viewSpaceTextPosition.Z);
spriteBatch.End();
device.RasterizerState = RasterizerState.CullCounterClockwise;
device.BlendState = BlendState.Opaque;
device.DepthStencilState = DepthStencilState.Default;
}
So is my use of Viewport wrong or do I just need to use it's information differently in spriteBatch.Draw()?
I think this should do the trick using viewport project... taking two projection points and calculating its distance you get a value affected by depth... so if it's deeper that value will be smaller.
public void Draw(Camera camera, GraphicsDevice device, SpriteBatch spriteBatch, Texture2D Texture)
{
Vector3 pos1= device.Viewport.Project(
this.position,
camera.Projection, camera.View, camera.World);
Vector3 pos2= device.Viewport.Project(
this.position+ Vactor3.UnitY*10,
camera.Projection, camera.View, camera.World);
Vector2 pos = new Vector2(pos1.X, pos1.Y);
Vector2 origin = new Vector2(Texture.Bounds.Center.X, Texture.Bounds.Center.Y);
float Scale = Vector3.Distance(pos1, pos2) * CustomRatio;
spriteBatch.Begin();
spriteBatch.Draw(Texture, pos, null, Color.White, 0,
origin, Scale, SpriteEffects.None, 0);
spriteBatch.End();
device.RasterizerState = RasterizerState.CullCounterClockwise;
device.BlendState = BlendState.Opaque;
device.DepthStencilState = DepthStencilState.Default;
}
In other hand... your previous code seems to be extracted from a source that drinks from this article made by the guy behind Xna that explain how to use basiceffect to draw billboards in 3D with spritebatch...
http://blogs.msdn.com/b/shawnhar/archive/2011/01/12/spritebatch-billboards-in-a-3d-world.aspx
I hope it helps you
Figured it out, you have to enable textures on the effect and then set effect.Texture to the Texture2D you want to use just before calling spriteBatch.Begin() in the draw function

XNA screenshot shows pre-Bloom, not final render

I have a windows platform game coded in C# XNA 4.0 using the Reach graphics settings. My project is based on the GameStateManagement sample but I later added Bloom and spriteSheet/spriteBatch functionality to it.
I desire to have a screenshot saved of the final screen output. However, when I save my screenshot it only shows the render before Bloom was applied and before my HUD text is displayed (which I draw after the Bloom). I have my screenshot saved at the end of my Draw method, after these two processes.
I have tried all kinds of things. Andrew's answer here Take screen shot in XNA was helpful and does save out an image; however, it is not saving out the final render.
I have a feeling it has something to do with the bloom process or maybe the spritebatch.
Here is my code:
example {
public override void Draw(GameTime gameTime)
{
ScreenManager.GraphicsDevice.SetRenderTarget(sceneRenderTarget);
// Clear the screen to black
ScreenManager.GraphicsDevice.Clear(ClearOptions.Target,
Color.Black, 0, 0);
SpriteBatch spriteBatch = ScreenManager.SpriteBatch;
spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend);
// then i draw all my game stuff
spriteBatch.End();
#region Post-Processing & Bloom
ScreenManager.GraphicsDevice.SamplerStates[1] = SamplerState.LinearClamp;
// Pass 1: draw the scene into rendertarget 1, using a
// shader that extracts only the brightest parts of the image.
bloomExtractEffect.Parameters["BloomThreshold"].SetValue(
Settings.BloomThreshold);
DrawFullscreenQuad(sceneRenderTarget, renderTarget1,
bloomExtractEffect,
IntermediateBuffer.PreBloom);
// Pass 2: draw from rendertarget 1 into rendertarget 2,
// using a shader to apply a horizontal gaussian blur filter.
SetBlurEffectParameters(1.0f / (float)renderTarget1.Width, 0);
DrawFullscreenQuad(renderTarget1, renderTarget2,
gaussianBlurEffect,
IntermediateBuffer.BlurredHorizontally);
// Pass 3: draw from rendertarget 2 back into rendertarget 1,
// using a shader to apply a vertical gaussian blur filter.
SetBlurEffectParameters(0, 1.0f / (float)renderTarget1.Height);
DrawFullscreenQuad(renderTarget2, renderTarget1,
gaussianBlurEffect,
IntermediateBuffer.BlurredBothWays);
// Pass 4: draw both rendertarget 1 and the original scene
// image back into the main backbuffer, using a shader that
// combines them to produce the final bloomed result.
ScreenManager.GraphicsDevice.SetRenderTarget(null);
EffectParameterCollection parameters = bloomCombineEffect.Parameters;
parameters["BloomIntensity"].SetValue(Settings.BloomIntensity);
parameters["BaseIntensity"].SetValue(Settings.BaseIntensity);
parameters["BloomSaturation"].SetValue(Settings.BloomSaturation);
parameters["BaseSaturation"].SetValue(Settings.BaseSaturation);
ScreenManager.GraphicsDevice.Textures[1] = sceneRenderTarget;
Viewport viewport = ScreenManager.GraphicsDevice.Viewport;
DrawFullscreenQuad(renderTarget1,
viewport.Width, viewport.Height,
bloomCombineEffect,
IntermediateBuffer.FinalResult);
#endregion
spriteBatch.Begin();
// Draw HUD
spriteBatch.End();
if (screenShotTake)
{
using (FileStream fs = File.Open(#"screenshot" + (screenshotNumber) + #".png", FileMode.OpenOrCreate))
{
// Right here I try to save out the screen shot Texture2D
sceneRenderTarget.SaveAsPng(fs, (int)viewportSize.X, (int)viewportSize.Y); // save render target to disk
}
}
}
#region PostProcess & Bloom
void DrawFullscreenQuad(Texture2D texture, RenderTarget2D renderTarget,
Effect effect, IntermediateBuffer currentBuffer)
{
ScreenManager.GraphicsDevice.SetRenderTarget(renderTarget);
DrawFullscreenQuad(texture,
renderTarget.Width, renderTarget.Height,
effect, currentBuffer);
}
void DrawFullscreenQuad(Texture2D texture, int width, int height,
Effect effect, IntermediateBuffer currentBuffer)
{
if (showBuffer < currentBuffer)
{
effect = null;
}
spriteBatch.Begin(0, BlendState.Opaque, null, null, null, effect);
spriteBatch.Draw(texture, new Rectangle(0, 0, width, height), Color.White);
spriteBatch.End();
}
}
The problem is here:
ScreenManager.GraphicsDevice.SetRenderTarget(null);
Because of this line, you draw the effects to the back buffer, but the render target you're saving is left alone. You see the results of the effects because it's drawn directly, but what you save is not what you've drawn to the back buffer. To fix this, draw the effects to another RenderTarget, and then draw that as a single texture to the back buffer. Obviously this is another draw call to process, but it's a minimal cost. By doing that, you can then grab the texture from the new RenderTarget and save it however you like.

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