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Search found 19 results on 1 pages for 'rendertargets'.

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• Can I animate render targets or the swap chain?

  - by Eric F.

  I want to animate some synthetic video bits to fullscreen w/o tearing. Can I set up D3D 9/10/11 in exclusive mode, and have it present a series of buffers that I'm writing to? I know how to copy system memory bits into a texture, then draw that texture as a fullscreen quad, but it seems like overkill. Why should I use the triangle rasterizer when I want to do something so simple? All I want to do is set up a long (4-8 buffer) swapchain and set the bits of the back buffer that is about to be displayed. Or, I want to allocate 4-8 RenderTargets, and on each frame, copy the bits from system memory to the RenderTarget, then set it as the next thing to display. I've never seen or heard about anybody doing this, but it seems so dead simple!

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• Possible to draw a select portion of a render target? (in XNA)

  - by TheBroodian

  I'm going to try to do this in reverse fashion and skip straight to the punch line, and then give the back story afterward: Is it possible to, after drawing a scene to a RenderTarget2D, only draw a select portion of the RenderTarget2D, if I don't want the entire thing? I'm using xTile to manage world data in my game (it's a great piece of work, colinvella [xTile's author] has made an amazing product), and for the most part it works great. xTile supports parallax effects in its layers to add some wonderful depth to 2d scenes, which was great, until I implemented a dynamic split-screen system into my game. Wanted to make a co-op game that wouldn't require players to be in close proximity to each other, so I made it so that if the players separate too far apart, the singular full-screen viewport 'snaps-apart', and is replaced by two split-screen viewports, which then smoothly transition to their respective player targets. The effect is pretty smooth aside from the part where the parallax backgrounds become skewed once the viewports split, because xTile's ratio for handling parallax effects is dependent upon viewport size. This is unfortunate, because the effect would otherwise be really snazzy, but the backgrounds become pretty heavily affected when the game goes from single-viewport to multi-viewport. So, Colinvella suggests using rendertargets to record the scene at full viewport size, and then only drawing a portion of it. But as far as I can tell, that isn't even possible? That being said, I've never even used render targets before, so I'm still learning, hence the question here.

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• Resolution independence - resize on the fly or ship all sizes?

  - by RecursiveCall

  My game relies heavily on textures of various sizes with some being full-screen. The game is targeted for multiple resolutions. I found that resizing textures (downsizing) works quite well for this game’s art type (it’s not Pixel Art or anything like that). I asked my artist to ensure that all textures at the edges of the screen to be created in such a way that they can safely “overflow” off screen; this means that aspect ratio is not an issue. So with no aspect ratio issues, I figured that I would simply ask my artist to create assets in very high resolution, and then resize them down to the appropriate screen resolution. The question is, when and how do I do that? Do I pre-resize everything to common resolutions in Photoshop and package all assets in the final product (increasing the size download that the user has to deal with) and then select the appropriate asset based on the detected resolution? Or do I ship with the largest set of Textures, detect the resolution on load, set a render target and draw all downsized assets to it and use that? Or for the latter, do I use some sort of a CPU-sided algorithm to resize on game load?

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• Render on other render targets starting from one already rendered on

  - by JTulip

  I have to perform a double pass convolution on a texture that is actually the color attachment of another render target, and store it in the color attachment of ANOTHER render target. This must be done multiple time, but using the same texture as starting point What I do now is (a bit abstracted, but what I have abstract is guaranteed to work singularly) renderOnRT(firstTarget); // This is working. for each other RT currRT{ glBindFramebuffer(GL_FRAMEBUFFER, currRT.frameBufferID); programX.use(); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, firstTarget.colorAttachmentID); programX.setUniform1i("colourTexture",0); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, firstTarget.depthAttachmentID); programX.setUniform1i("depthTexture",1); glBindBuffer(GL_ARRAY_BUFFER, quadBuffID); // quadBuffID is a VBO for a screen aligned quad. It is fine. programX.vertexAttribPointer(POSITION_ATTRIBUTE, 3, GL_FLOAT, GL_FALSE, 0, (void*)0); glDrawArrays(GL_QUADS,0,4); programY.use(); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, currRT.colorAttachmentID); // The second pass is done on the previous pass programY.setUniform1i("colourTexture",0); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, currRT.depthAttachmentID); programY.setUniform1i("depthTexture",1); glBindBuffer(GL_ARRAY_BUFFER, quadBuffID); programY.vertexAttribPointer(POSITION_ATTRIBUTE, 3, GL_FLOAT, GL_FALSE, 0, (void*)0); glDrawArrays(GL_QUADS, 0, 4); } The problem is that I end up with black textures and not the wanted result. The GLSL programs program(X,Y) works fine, already tested on single targets. Is there something stupid I am missing? Even an hint is much appreciated, thanks!

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• Writing to a D3DFMT_R32F render target clamps to 1

  - by Mike

  I'm currently implementing a picking system. I render some objects in a frame buffer, which has a render target, which has the D3DFMT_R32F format. For each mesh, I set an integer constant evaluator, which is its material index. My shader is simple: I output the position of each vertex, and for each pixel, I cast the material index in float, and assign this value to the Red channel: int ObjectIndex; float4x4 WvpXf : WorldViewProjection< string UIWidget = "None"; >; struct VS_INPUT { float3 Position : POSITION; }; struct VS_OUTPUT { float4 Position : POSITION; }; struct PS_OUTPUT { float4 Color : COLOR0; }; VS_OUTPUT VSMain( const VS_INPUT input ) { VS_OUTPUT output = (VS_OUTPUT)0; output.Position = mul( float4(input.Position, 1), WvpXf ); return output; } PS_OUTPUT PSMain( const VS_OUTPUT input, in float2 vpos : VPOS ) { PS_OUTPUT output = (PS_OUTPUT)0; output.Color.r = float( ObjectIndex ); output.Color.gba = 0.0f; return output; } technique Default { pass P0 { VertexShader = compile vs_3_0 VSMain(); PixelShader = compile ps_3_0 PSMain(); } } The problem I have, is that somehow, the values written in the render target are clamped between 0.0f and 1.0f. I've tried to change the rendertarget format, but I always get clamped values... I don't know what the root of the problem is. For information, I have a depth render target attached to the frame buffer. I disabled the blend in the render state the stencil is disabled Any ideas?

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• DX9 Deferred Rendering, GBuffer displays as clear color only

  - by Fire31

  I'm trying to implement Catalin Zima's Deferred Renderer in a very lightweight c++ DirectX 9 app (only renders a skydome and a model), at this moment I'm trying to render the gbuffer, but I'm having a problem, the screen shows only the clear color, no matter how much I move the camera around. However, removing all the render target operations lets the app render the scene normally, even if the models are being applied the renderGBuffer effect. Any ideas of what I'm doing wrong?

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• How to manage drawing loop when changing render targets

  - by George Duckett

  I'm managing my game state by having a base GameScreen class with a Draw method. I then have (basically) a stack of GameScreens that I render. I render the bottom one first, as screens above might not completely cover the ones below. I now have a problem where one GameScreen changes render targets while doing its rendering. Anything the previous screens have drawn to the backbuffer is lost (as XNA emulates what happens on the xbox). I don't want to just set the backbuffer to preserve its contents as I want this to work on the xbox as well as PC. How should I manage this problem? A few ideas I've had: Render every GameScreen to its own render target, then render them all to the backbuffer. Create some kind of RenderAction queue where a game screen (and anything else I guess) could queue something to be rendered to the back buffer. They'd render whatever they wanted to any render target as normal, but if they wanted to render to the backbuffer they'd stick that in a queue which would get processed once all rendertarget rendering was done. Abstract away from render targets and backbuffers and have some way of representing the way graphics flows and transforms between render targets and have something manage/work out the correct rendering order (and render targets) given what rendering process needs as input and what it produces as output. I think each of my ideas have pros and cons and there are probably several other ways of approaching this general problem so I'm interested in finding out what solutions are out there.

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• Proper way to use a RenderTarget2D to draw multiple textures?

  - by TheBroodian

  In the process of trying to resolve a split screen issue, I've been trying to use a RenderTarget2D to draw a portion of my scene to a Texture2D, and then again to another Texture2D, but the end result of both Texture2D's is coming out the same. Can anybody tell me what I'm doing wrong? Texture2D camera1Render; Texture2D camera2Render; GraphicsDevice.SetRenderTarget(RenderTarget); GraphicsDevice.Clear(Color.Transparent); map.Draw(mapDisplayDevice, Camera1, new Location(0, 0), false); camera1Render = RenderTarget; GraphicsDevice.Clear(Color.Transparent); map.Draw(mapDisplayDevice, Camera2, new Location(0, 0), false); camera2Render = RenderTarget; SetRenderTarget(null);

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• Can't change color of sprites in unity

  - by Aceleeon

  I would like to create a script that targets a 2d sprite "enemy" and changes their color to red (slightly opaque red if possible) when you hit tab. I have this code from a 3d tutorial hoping the transition would work. But it does not. I only get the script to cycle the enemy tags but never changes the color of the sprite. I have the code below I'm very new to coding, and any help would be FANTASTIC! HELP! hahah. TL;DR Cant get 3d color targeting to work for 2D. Check out the c#code below using UnityEngine; using System.Collections; using System.Collections.Generic; public class Targetting : MonoBehaviour { public List targets; public Transform selectedTarget; private Transform myTransform; // Use this for initialization void Start () { targets = new List(); selectedTarget = null; myTransform = transform; AddAllEnemies(); } public void AddAllEnemies() { GameObject[] go = GameObject.FindGameObjectsWithTag("Enemy"); foreach(GameObject enemy in go) AddTarget(enemy.transform); } public void AddTarget(Transform enemy) { targets.Add(enemy); } private void SortTargetsByDistance() { targets.Sort(delegate(Transform t1,Transform t2) { return Vector3.Distance(t1.position, myTransform.position).CompareTo(Vector3.Distance(t2.position, myTransform.position)); }); } private void TargetEnemy() { if(selectedTarget == null) { SortTargetsByDistance(); selectedTarget = targets[0]; } else { int index = targets.IndexOf(selectedTarget); if(index < targets.Count -1) { index++; } else { index = 0; } selectedTarget = targets[index]; } } private void SelectTarget() { selectedTarget.GetComponent().color = Color.red; } private void DeselectTarget() { selectedTarget.GetComponent().color = Color.blue; selectedTarget = null; } // Update is called once per frame void Update() { if(Input.GetKeyDown(KeyCode.Tab)) { TargetEnemy(); } } }

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• XNA - Obtaining depth from the scene's render target?

  - by user1423893

  I'm currently rendering my scene to a render target so it can be used for rendering methods such as post processing and order independent transparency. rtScene = new RenderTarget2D( GraphicsDevice, GraphicsDevice.PresentationParameters.BackBufferWidth, GraphicsDevice.PresentationParameters.BackBufferHeight, false, SurfaceFormat.Rgba64, DepthFormat.Depth24Stencil8, // Requires a depth format for objects to be drawn correctly (e.g. wireframe model surrounding model) 0, RenderTargetUsage.PreserveContents ); I am required to use RenderTargetUsage.PreserveContents so that the same render target can be rendered to multiple times, once for each of the draw methods below. DrawBackground DrawDeferred DrawForward DrawTransparent The problem is that DrawTransparent requires a copy of the scene's depth as a texture. Is there any way to obtain this from the scene render target above (rtScene)? I can't have more than one render target with RenderTargetUsage.PreserveContents as this causes problems on hardware such as the XBOX 360, so rendering the depth to a separate render target at the same time as I render the scene isn't possible as far as I can tell. Would I be able to get around this problem by "Ping-Ponging" two render targets (using the more compatible RenderTargetUsage.DiscardContents) and using the result for the depth texture?

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• XNA 4: RenderTarget2D textures getting transparent on fullscreen

  - by Shashwat

  I'm generating a Texture2D object using RenderTarget2D as in the following code public static Texture2D GetTextTexture(string text, Vector2 position, SpriteFont font, Color foreColor, Color backColor, Texture2D background=null) { int width = (int)font.MeasureString(text).X; int height = (int)font.MeasureString(text).Y; GraphicsDevice device = Settings.game.GraphicsDevice; SpriteBatch spriteBatch = Settings.game.spriteBatch; RenderTarget2D renderTarget = new RenderTarget2D(device, width, height, false, SurfaceFormat.Color, DepthFormat.Depth24Stencil8, device.PresentationParameters.MultiSampleCount, RenderTargetUsage.DiscardContents); device.SetRenderTarget(renderTarget); device.Clear(backColor); spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.Opaque); if (background != null) spriteBatch.Draw(background, new Rectangle(0, 0, 70, 70), Color.White); spriteBatch.End(); spriteBatch.Begin(); spriteBatch.DrawString(font, text, position, foreColor, 0, new Vector2(0), 0.8f, SpriteEffects.None, 0); spriteBatch.End(); device.SetRenderTarget(null); ResetGraphicsDeviceSettings(); return (Texture2D)renderTarget; } It's working all fine. But when I ToggleFullScreen() (and vice-versa), the previous textures are getting transparent. However, the new textures after that are being generated correctly. What can be the reason for this?

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• Possible / How to render to multiple back buffers, using one as a shader resource when rendering to the other, and vice versa?

  - by Raptormeat

  I'm making a game in Direct3D10. For several of my rendering passes, I need to change the behavior of the pass depending on what is already rendered on the back buffer. (For example, I'd like to do some custom blending- when the destination color is dark, do one thing; when it is light, do another). It looks like I'll need to create multiple render targets and render back and forth between them. What's the best way to do this? Create my own render textures, use them, and then copy the final result into the back buffer. Create multiple back buffers, render between them, and then present the last one that was rendered to. Create one render texture, and one back buffer, render between them, and just ensure that the back buffer is the final target rendered to I'm not sure which of these is possible, and if there are any performance issues that aren't obvious. Clearly my preference would be to have 2 rather than 3 default render targets, if possible.

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• IDirect3DDevice9::GetRenderTargetData() returns no data

  - by P. Avery

  I've got a simple function to get the rendertarget data of an RT( w/default pool ). This particular RT has a resolution of 1x1( it's the 10'th and final mip of a texture ). Here is my code to get data for IDirect3DSurface9 *pTargetSurface: IDirect3DSurface9 *pSOS = NULL; pd3dDevice->CreateOffScreenPlainSurface( 1, 1, D3DFMT_A8R8G8B8, D3DPOOL_SYSTEMMEM, &pSOS, NULL ); // get residual energy if( FAILED( hr = pd3dDevice->GetRenderTargetData( pTargetSurface, pSOS ) ) ) { DebugStringDX( ClassName, "Failed to IDirect3DDevice9::GetRenderTargetData() at DownsampleArea()", __LINE__, hr ); goto Exit; } // lock surface if( FAILED( hr = pSOS->LockRect( &rct, NULL, D3DLOCK_READONLY ) ) ) { DebugStringDX( ClassName, "Failed to IDirect3DSurface9::LockRect() at DownsampleArea()", __LINE__, hr ); goto Exit; } // get residual energy from downsampled texture pByte = ( BYTE* )rct.pBits; D3DXVECTOR4 vEnergy; vEnergy.z = ( float )pByte[ 0 ] / 255.0f; vEnergy.y = ( float )pByte[ 1 ] / 255.0f; vEnergy.x = ( float )pByte[ 2 ] / 255.0f; vEnergy.w = ( float )pByte[ 3 ] / 255.0f; V( pSOS->UnlockRect() ); All formatting and settings are correct, directx in debug mode shows no errors... The problem is that the 4 bytes above are 0...I know this to be incorrect by using PIX to debug...PIX shows that RGB bytes are 0.078 and Alpah is 1. These values are not less than that which can be represented by a single byte( 1 / 255 ). Any ideas? Am I copying rendertarget data correctly?

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• What should I do if my text exceeds my text render target boundaries?

  - by user1423893

  I have a method for drawing strings in 3D that does the following: Set a render target Draw each character as a quadrangle using a orthographic projection to the render target Unset the render target Draw the render target texture using a perspective projection and a world transform My problem is how to deal with strings whose characters length exceeds that of the render target dimensions? For example if I have string "This is a reallllllllllly long string" and the render target can't accommodate it, it will only capture "This is a realllll". The render target (and its size) could be set each frame but wouldn't that be far too costly?

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• How do I render from one render target to another?

  - by Chaotikmind

  I have two render targets: a fake backbuffer; a special render target where I do all my rendering. a light render target; where I render my light fx. I'm sure I'm rendering correctly on both. The problem arises when I overlay the light render target onto the fake backbuffer by drawing a quad covering it: DxEngine.DrawSprite(0.0f, 0.0f, 0.0f, (float)DxEngine.GetWidth(), (float)DxEngine.GetHeight(), 0xFFFFFFFF, LightSurface->GetTexture()); Regardless of what's in the light target, nothing is rendered onto the other target. I tried clearing the light target with full-white or full-black, but still get nothing. Fake backbuffer created with Direct3dDev->CreateTexture(Width, Height, 1, D3DUSAGE_RENDERTARGET, D3DFMT_X8R8G8B8, D3DPOOL_DEFAULT, &Texture, nullptr); Light render target created with Direct3dDev->CreateTexture(Width, Height, 1, D3DUSAGE_RENDERTARGET, D3DFMT_A8R8G8B8, D3DPOOL_DEFAULT, &Texture, nullptr); I also tried to create both with D3DFMT_A8R8G8B8, again without difference. Both targets have the same width and height. Only the fixed pipeline is used DirectX setup for rendering : Direct3dDev->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR ); Direct3dDev->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR ); Direct3dDev->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_NONE ); Direct3dDev->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_WRAP ); Direct3dDev->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_WRAP ); Direct3dDev->SetRenderState(D3DRS_CULLMODE, D3DCULL_NONE); Direct3dDev->SetRenderState(D3DRS_LIGHTING, false); Direct3dDev->SetRenderState(D3DRS_ZENABLE, D3DZB_TRUE); Direct3dDev->SetRenderState(D3DRS_ZWRITEENABLE,D3DZB_TRUE); Direct3dDev->SetRenderState(D3DRS_ZFUNC,D3DCMP_LESSEQUAL); Direct3dDev->SetRenderState(D3DRS_ALPHABLENDENABLE, true ); Direct3dDev->SetRenderState(D3DRS_ALPHAREF, 0x00000000ul); Direct3dDev->SetRenderState(D3DRS_ALPHATESTENABLE, true); Direct3dDev->SetRenderState(D3DRS_ALPHAFUNC,D3DCMP_GREATER); Direct3dDev->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA ); Direct3dDev->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA ); Direct3dDev->SetTextureStageState(0, D3DTSS_COLORARG1, D3DTA_TEXTURE); Direct3dDev->SetTextureStageState(0, D3DTSS_COLORARG2, D3DTA_DIFFUSE); Direct3dDev->SetTextureStageState(0, D3DTSS_COLOROP, D3DTOP_MODULATE); Direct3dDev->SetTextureStageState(0, D3DTSS_ALPHAARG1, D3DTA_TEXTURE); Direct3dDev->SetTextureStageState(0, D3DTSS_ALPHAARG2, D3DTA_DIFFUSE); Direct3dDev->SetTextureStageState(0, D3DTSS_ALPHAOP, D3DTOP_MODULATE); Direct3dDev->SetTextureStageState(0, D3DTSS_RESULTARG, D3DTA_CURRENT); Direct3dDev->SetTextureStageState(0, D3DTSS_TEXCOORDINDEX, D3DTSS_TCI_PASSTHRU); //ensure the first stage is not used for now Direct3dDev->SetTextureStageState(1, D3DTSS_COLOROP, D3DTOP_DISABLE); How can I do this right?

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• Multiple render targets and gamma correctness in Direct3D9

  - by Mario

  Let's say in a deferred renderer when building your G-Buffer you're going to render texture color, normals, depth and whatever else to your multiple render targets at once. Now if you want to have a gamma-correct rendering pipeline and you use regular sRGB textures as well as rendertargets, you'll need to apply some conversions along the way, because your filtering, sampling and calculations should happen in linear space, not sRGB space. Of course, you could store linear color in your textures and rendertargets, but this might very well introduce bad precision and banding issues. Reading from sRGB textures is easy: just set SRGBTexture = true; in your texture sampler in your HLSL effect code and the hardware does the conversion sRGB-linear for you. Writing to an sRGB rendertarget is theoretically easy, too: just set SRGBWriteEnable = true; in your effect pass in HLSL and your linear colors will be converted to sRGB space automatically. But how does this work with multiple rendertargets? I only want to do these corrections to the color textures and rendertarget, not to the normals, depth, specularity or whatever else I'll be rendering to my G-Buffer. Ok, so I just don't apply SRGBTexture = true; to my non-color textures, but when using SRGBWriteEnable = true; I'll do a gamma correction to all the values I write out to my rendertargets, no matter what I actually store there. I found some info on gamma over at Microsoft: http://msdn.microsoft.com/en-us/library/windows/desktop/bb173460%28v=vs.85%29.aspx For hardware that supports Multiple Render Targets (Direct3D 9) or Multiple-element Textures (Direct3D 9), only the first render target or element is written. If I understand correctly, SRGBWriteEnable should only be applied to the first rendertarget, but according to my tests it doesn't and is used for all rendertargets instead. Now the only alternative seems to be to handle these corrections manually in my shader and only correct the actual color output, but I'm not totally sure, that this'll not have any negative impact on color correctness. E.g. if the GPU does any blending or filtering or multisampling after the Linear-sRGB conversion... Do I even need gamma correction in this case, if I'm just writing texture color without lighting to my rendertarget? As far as I know, I DO need it because of the texture filtering and mip sampling happening in sRGB space instead, if I don't correct for it. Anyway, it'd be interesting to hear other people's solutions or thoughts about this.

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• Skip the first RenderTarget when writing to MRT with Opaque blending

  - by cubrman

  I am writing to three rendertargets and whant to know how to tell a GPU not to write to the first RT. When you write a shader you can simply output less data than you have RTs (like output a single float4 when writing to three RTs) and only the first RTs will be affected, but you cannot specify to output this data anywhere else but to COLOR0, then 1, etc. Is there a way to write to several RTs but skip the first target? If I output zeroes, the data in the target will become zeroes, but I need it to remain untuched in the first target and only change in the specified ones. The reason I need this is to prevent data loss when calling SetRendertarget() with DiscardContents RTs. I write to all the RTs at one point and I need to write to only the specified ones afterwards. It must be the first texture as I have a depth buffer linked to it (XNA 4.0). Thanks.

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• Best way to mask 2D sprites in XNA?

  - by electroflame

  I currently am trying to mask some sprites. Rather than explaining it in words, I've made up some example pictures: The area to mask (in white) Now, the red sprite that needs to be cropped. The final result. Now, I'm aware that in XNA you can do two things to accomplish this: Use the Stencil Buffer. Use a Pixel Shader. I have tried to do a pixel shader, which essentially did this: float4 main(float2 texCoord : TEXCOORD0) : COLOR0 { float4 tex = tex2D(BaseTexture, texCoord); float4 bitMask = tex2D(MaskTexture, texCoord); if (bitMask.a > 0) { return float4(tex.r, tex.g, tex.b, tex.a); } else { return float4(0, 0, 0, 0); } } This seems to crop the images (albeit, not correct once the image starts to move), but my problem is that the images are constantly moving (they aren't static), so this cropping needs to be dynamic. Is there a way I could alter the shader code to take into account it's position? Alternatively, I've read about using the Stencil Buffer, but most of the samples seem to hinge on using a rendertarget, which I really don't want to do. (I'm already using 3 or 4 for the rest of the game, and adding another one on top of it seems overkill) The only tutorial I've found that doesn't use Rendertargets is one from Shawn Hargreaves' blog over here. The issue with that one, though is that it's for XNA 3.1, and doesn't seem to translate well to XNA 4.0. It seems to me that the pixel shader is the way to go, but I'm unsure of how to get the positioning correct. I believe I would have to change my onscreen coordinates (something like 500, 500) to be between 0 and 1 for the shader coordinates. My only problem is trying to work out how to correctly use the transformed coordinates. Thanks in advance for any help!

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• Using SurfaceFormat.Single and HLSL for GPGPU with XNA

  - by giancarlo todone

  I'm trying to implement a so-called ping-pong technique in XNA; you basically have two RenderTarget2D A and B and at each iteration you use one as texture and the other as target - and vice versa - for a quad rendered through an HLSL pixel shader. step1: A--PS--B step2: B--PS--A step3: A--PS--B ... In my setup, both RenderTargets are SurfaceFormat.Single. In my .fx file, I have a tachnique to do the update, and another to render the "current buffer" to the screen. Before starting the "ping-pong", buffer A is filled with test data with SetData<float>(float[]) function: this seems to work properly, because if I render a quad on the screen through the "Draw" pixel shader, i do see the test data being correctly rendered. However, if i do update buffer B, something does not function proerly and the next rendering to screen will be all black. For debug purposes, i replaced the "Update" HLSL pixel shader with one that should simply copy buffer A into B (or B into A depending on which among "ping" and "pong" phases we are...). From some examples i found on the net, i see that in order to correctly fetch a float value from a texture sampler from HLSL code, i should only need to care for the red channel. So, basically the debug "Update" HLSL function is: float4 ComputePS(float2 inPos : TEXCOORD0) : COLOR0 { float v1 = tex2D(bufSampler, inPos.xy).r; return float4(v1,0,0,1); } which still doesn't work and results in a all-zeroes ouput. Here's the "Draw" function that seems to properly display initial data: float4 DrawPS(float2 inPos : TEXCOORD0) : COLOR0 { float v1 = tex2D(bufSampler, inPos.xy).r; return float4(v1,v1,v1,1); } Now: playing around with HLSL doesn't change anything, so maybe I'm missing something on the c# side of this, so here's the infamous Update() function: _effect.Parameters["bufTexture"].SetValue(buf[_currentBuf]); _graphicsDevice.SetRenderTarget(buf[1 - _currentBuf]); _graphicsDevice.Clear(Color.Black); // probably not needed since RenderTargetUsage is DiscardContents _effect.CurrentTechnique = _computeTechnique; _computeTechnique.Passes[0].Apply(); _quadRender.Render(); _graphicsDevice.SetRenderTarget(null); _currentBuf = 1 - _currentBuf; Any clue?

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