I have a really weird problem. I render some triangles in the scene with D3D10 and what is surprising is that color values of these pixels are not clipped against near/far planes. On the other hand, depth values seem to be clipped fine. Evidence that this works as I have just described is as following:
when I render objects in the z-range that is "within" view frustum, everything is fine
when one object is inside the z-range and one is in front of it (between camera's eye and near plane), the objects inside the z-range "shines thhrough" the object that is closer. So z-buffering is working perfectly fine
I also checked output VS vertices values; all vertices that are outside the z-range and should be clipped (and they are in the z-buffer but are not in the color buffer) have their Z/W values outside [0, 1] interval
Idea idea what could be wrong? I think it might be some render state set incorrectly but I don't really know where to look.
I'm making your comment an answer, as it was exactly the issue I had in D3D11 (same in D3D10).
Make sure that you set DepthClipEnable to TRUE in any D3D11_RASTERIZER_DESC in question.
Related
I'm trying to add a directional light in Scenekit to cast shadows, but it is causing weird artefacts on objects.
The orange block below has a material with default settings and the diffuse set to orange.
The directional light is pointing downwards, and the scale is increased, otherwise it has default settings. (Making the scale smaller still has the same issue).
When I pan the camera around the texture is covered in flickering lines and dots, it looks terrible.
This isn't visible on the simulator, only the device. What is going on and how can I fix it?
Thanks to Toyos I now know that self-shadowing is what's causing the lines. The docs for shadowBias say setting this value should correct it, but for me it made no difference.
In the end I fixed it by rotating the directional light by 2 degrees. It was originally at -90, pointing straight down. Changing this to -88 has completely removed all the artefacts.
Configure the zNear/zFar range of your light to make it as small as possible (but not clipping your world). The smaller the zRange is the more precision you will get.
You can also play with the shadowBias to limit the self shadowing artefacts
I'm currently working on a XNA project where I need to create a Picture in picture Overlay to displaying a 3D scene from multiple angles. currently I'm trying to use 2 viewports to do this. The main one fills whole screen and is working as desired. The second is placed in one of the corners of the first (overlapping that corner) and is less than a 5th of the size as the first. apart from the size and placement of the viewports the only thing really difference between the 2 is the placement of their cameras with-in the scene.
As long as the second viewport is drawn second and there are no objects close to the camera of the first viewport in the overlapping corner this actually works greate. However if there is an object close to the camera and in the corner of the first viewport objects seem to experience occlusion culling as a result of the first viewport's object. The occluding object of the first viewport is not shown in the second viewports space though.
My question is how would one prevent the "cross viewport culling" from happening? I've searched all over and the closes threads I could find suggest drawing the second viewport to a RenderTarget2D and using a SpriteBatch to display the resulting texture. Though doing so does fix the occlusion issue it does mayhem on the z ordering, CCW culling, and my water effects all of which I've never had issue with using the default render target.
This issue, at least in my case, Seems to have been resolved by simply clearing the depth buffer between drawing the 2 Viewports. I did this by adding the following line between the function calls that draws the individual Viewports
GraphicsDevice.Clear(ClearOptions.DepthBuffer, Color.Black, 1, 0);
I ran in to this solution while trying to use the Stencil buffer to prevent the Main viewport from drawing under the second, but everything I did before this discovery did not really have a noticeable effect. After I removed all the Stencil code and it looks like I'm getting the desired effect. Sorry but I can't really explain how or why this works without messing up the first Viewport cause I have no clue myself.
I have been searching from last two days on internet, I have checked many source codes on net but none of them has provided the result I want.
The image rotation would have perspective but still there would be no changes in the heights of both left and right sides of an image.
I want to set image inside the laptop screen
Please help me out, Thanks.
So you want to 2D pespective drawing of a laptop screen (on an iOS device?) and put a 2D image on that screen, but with the image transformed so its perspective looks correct on the laptop screen, right?
What you need to do is to add an image view on top of your laptop image view. Lets call it laptopScreenImageView.
Then apply a CATransform3D to that the laptopScreenImageView's layer.
The trick to get 3D perspective out of a CALayer is to modify the .m34 value of the transform. Typically you set the .m34 value to a very small negative number, somewhere around -1/200 to -1/500 (the denominator in the fraction is the z coordinate of the "eye position" for viewing the perspective image, in pixels, or how many pixels "above" the image the viewer's eye should seem to be. I don't fully understand it, to be honest. I fiddle with the .m34 value until I get something that looks right.)
Alternately you could try adding a CATransformLayer to your laptop image view's layer, and then adding a CALayer containing your image as a sublayer of the CATransformLayer. I haven't used CATransformLayers before, but the docs say they are supposed to support layers with 3D perspective, giving you the same effect as modifying the .m34 component of a layer's transform.
We are working on a Three.js based WebGL project, and have trouble understanding how transparency is handled in WebGL. The image shows a doublesided surface drawn with alpha = 0.7, which behaves correctly on its right side. However closer to the middle strange artifacts appear, and on the left side the transparency does not seem to work at all.
http://emilaxelsson.se/sandbox/vis1/alpha.png
The problem can also be seen here:
http://emilaxelsson.se/sandbox/vis1/
Has anyone seen anything similar before? What could the reason be?
Your problem is that transparent objects needs to be sorted and rendered in a back-to-front order (if you try to change the opacity of your mesh from 0.7 (transparent) to 1.0 (opaque), you can see that the z-buffer works just fine).
See:
http://www.opengl.org/wiki/Transparency_Sorting
http://www.opengl.org/archives/resources/faq/technical/transparency.htm (15.050)
In your case it might be less trivial to solve, since I assume that you only have one mesh.
Edit: Just to summarize the discussion below. It is possible to achieve correct rendering of such a double-sided transparent mesh. To do this, you need to create 6 versions of the mesh, corresponding to 6 sides of a cube. Each version needs to be sorted in a back-to-front order based on the 'side of the cube' (front, back, left, right, top, bottom).
When rendering choose the correct mesh (based on the camera viewing direction) and render that single mesh.
The easy solution for your case (based on the picture you attached), without going to expensive sorting and multiple meshes, is to disable depth test and enable face culling. That produces acceptable results if you do not have any opaque objects in front of the mesh.
I have written a 2D Jump&Run Engine resulting in a 320x224 (320x240) image. To maintain the old school "pixely"-feel to it, I would like to scale the resulting image by 2 or 3 or 4, according to the resolution of the user.
I don't want to scale each and every sprite, but the resulting image!
Thanks in advance :)
Bob's answer is correct about changing the filtering mode to TextureFilter.Point to keep things nice and pixelated.
But possibly a better method than scaling each sprite (as you'd also have to scale the position of each sprite) is to just pass a matrix to SpriteBatch.Begin, like so:
sb.Begin(/* first three parameters */, Matrix.CreateScale(4f));
That will give you the scaling you want without having to modify all your draw calls.
However it is worth noting that, if you use floating-point offsets in your game, you will end up with things not aligned to pixel boundaries after you scale up (with either method).
There are two solutions to this. The first is to have a function like this:
public static Vector2 Floor(Vector2 v)
{
return new Vector2((float)Math.Floor(v.X), (float)Math.Floor(v.Y));
}
And then pass your position through that function every time you draw a sprite. Although this might not work if your sprites use any rotation or offsets. And again you'll be back to modifying every single draw call.
The "correct" way to do this, if you want a plain point-wise scale-up of your whole scene, is to draw your scene to a render target at the original size. And then draw your render target to screen, scaled up (with TextureFilter.Point).
The function you want to look at is GraphicsDevice.SetRenderTarget. This MSDN article might be worth reading. If you're on or moving to XNA 4.0, this might be worth reading.
I couldn't find a simpler XNA sample for this quickly, but the Bloom Postprocess sample uses a render target that it then applies a blur shader to. You could simply ignore the shader entirely and just do the scale-up.
You could use a pixelation effect. Draw to a RenderTarget2D, then draw the result to the screen using a Pixel Shader. There's a tool called Shazzam Shader Editor that let's you try out pixel shaders and it includes one that does pixelation:
http://shazzam-tool.com/
This may not be what you wanted, but it could be good for allowing a high-resolution mode and for having the same effect no matter what resolution was used...
I'm not exactly sure what you mean by "resulting in ... an image" but if you mean your end result is a texture then you can draw that to the screen and set a scale:
spriteBatch.Draw(texture, position, source, color, rotation, origin, scale, effects, depth);
Just replace the scale with whatever number you want (2, 3, or 4). I do something similar but scale per sprite and not the resulting image. If you mean something else let me know and I'll try to help.
XNA defaults to anti-aliasing the scaled image. If you want to retain the pixelated goodness you'll need to draw in immediate sort mode and set some additional parameters:
spriteBatch.Begin(SpriteBlendMode.AlphaBlend, SpriteSortMode.Immediate, SaveStateMode.None);
GraphicsDevice.SamplerStates[0].MagFilter = TextureFilter.Point;
GraphicsDevice.SamplerStates[0].MinFilter = TextureFilter.Point;
GraphicsDevice.SamplerStates[0].MipFilter = TextureFilter.Point;
It's either the Point or the None TextureFilter. I'm at work so I'm trying to remember off the top of my head. I'll confirm one way or the other later today.