• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0

How to populate a DX texture with random RGB values.

3 posts in this topic

I am trying get 3 new random floats into my pixel shader for each pixel. Based on what I have read here, here, and also here, I believe that I need to generate a large texture containing random RGB values and then during each draw call randomly generate a couple of texture coordinate offset values to produce a pseudo-random effect. Is the only way to do this through the LockRect and UnlockRect API? I hope not. Also when do the floating point color values get quantized. For example if I do a ColorFill on a texture and set it too a RGB of ( 0.52, 0.52, 0.52 )
which on a 0-255 scale is ( 132.6, 132.6, 132. 6 ) when I access that texture in my pixel shader will I get a value of 0.52 or 0.52156....i.e. (133).

Share this post

Link to post
Share on other sites
You may create a texture with random numbers by locking the texture and filling it with CPU generate random values.
If you are just after noise, you can precreate a texture (in photoshop or similar program) containing noise.

The values you can store in the texture depends on the surface format. RGBA8 format for example contains values 0-255 for each channel which maps to range [0..1]. RGBA8 texture can contain only integer values, which means that value stored for 0.52 should be multiplied by 255 before storing in the texture and it will result 132 or 133 depending on rounding. The value that the shader read from the texture is 133/255=0,521568...

You may use another texture format to get more precision if required.


Share this post

Link to post
Share on other sites
You can directly utilize a floating point format texture, in which case you don't have to settle for any quantization. There are a couple of ways to get data into a texture, including passing the data during texture creation, using map/unmap, and using update subresource. Each of these methods have their own requirements, but the info is readily available on the net.

Share this post

Link to post
Share on other sites
I am trying to write an HLSL pixel shader for a project I am working on. Basically want I want to do is if a texture has a pixel with a float value of 0.52 (on scale of 0-255 is 132.6) I want to output 133 60% of the time and output 132 40% of the time. Write now I am just trying to output the fractional remainder of the RGB value (i.e. the chance to bump the pixel up) however I always get a value of zero) I think this is because the colors are getting quantized to a 0-255 scale before they reach the shader but I don't know why this would be because I am useing the A32B32G32R32f format which should be able to store plenty of information about the colors. Here is my very simple shader code. I am using SlimDX (DX9) if that matters.

sampler2D Tex0 : register(s0);
float4 DitherByChance(float2 coords : TEXCOORD0) : COLOR
float4 newColor = float4(0, 0, 0, 0); // The pixel color to return
double4 oldColor = tex2D(Tex0, coords);
double scale = 0.0039215686274509803921568627451; // 1 / 255
double rPercentChance = frac(oldColor.r / scale); //Chance to round red channel up
double gPercentChance = frac(oldColor.g / scale); //Chance to round green channel up
double bPercentChance = frac(oldColor.b / scale); //Chance to round blue channel up
newColor.r = rPercentChance;
newColor.g = gPercentChance;
newColor.b = bPercentChance;
newColor.a = 1;
return newColor;
technique DitherViaChance
pass Pass1
PixelShader = compile ps_2_0 DitherByChance();

Here is my SlimDX code too if you want to look:

Public Class TextStimulusDisplay
Inherits BaseStimulusDisplay
Protected ditherByChanceEffect As PixelShader
Protected psByteCode As ShaderBytecode
Protected gStream As DataStream
Protected ditherBC As Effect
Protected tex As Texture
Protected spriteRender As Sprite
Public displaySettings As DisplaySettings
Public charText As Texture
Public randomText As Texture
Protected rando As Random
Public Sub New(ByVal displaysettings As DisplaySettings, Optional ByVal WindowedMode As Boolean = False)
MyBase.New(New Size(displaysettings.xResolution, displaysettings.yResolution), WindowedMode)
Me.displaySettings = displaysettings
End Sub
Public Overrides Sub CreateDeviceResources()
ditherBC = Effect.FromFile(device, Application.StartupPath & "\effects\DitherByChance.fx", ShaderFlags.Debug)
rando = New Random()
randomText = New Texture(device, 100, 100, 1, Usage.Dynamic, Format.A32B32G32R32F, Pool.Default)
Dim data(80000) As Byte
Dim dataBox As DataRectangle = randomText.GetSurfaceLevel(0).LockRectangle(LockFlags.None)
dataBox.Data.Seek(0, IO.SeekOrigin.Begin)
dataBox.Data.Write(data, 0, data.Length)
device.SetTexture(1, randomText)
'psByteCode = ShaderBytecode.CompileFromFile(Application.StartupPath & "\effects\DitherByChance.fx", "DitherByChance", "ps_2_0", ShaderFlags.None)
'ditherByChanceEffect = New PixelShader(device, psByteCode)
'device.PixelShader = ditherByChanceEffect
spriteRender = New Sprite(device)
spriteRender.Transform = Matrix.Identity
tex = createCharacterTexture()
End Sub
Public Overrides Sub ReleaseDeviceResources()
End Sub
Public Overrides Sub RenderScene()
'ditherBC.Technique = ditherBC.GetTechnique("DitherViaChance")
spriteRender.Draw(tex, New Rectangle(0, 0, 50, 50), New Color4(1, 1, 1))
'spriteRender.Draw(randomText, New Rectangle(0, 0, 1000, 1000), New Color4(1, 1, 1))
End Sub
Public Function createCharacterTexture() As Texture
Dim RtsHelper As RenderToSurface = New RenderToSurface(device, 100, 100, Format.A32B32G32R32F)
Dim texture As Texture = New Texture(device, 100, 100, 1, Usage.RenderTarget, Format.A32B32G32R32F, Pool.Default)
Dim sloanFont As Font = New Font(device, 98, 98, FontWeight.Normal, 1, False, CharacterSet.Default, Precision.Default,
FontQuality.ClearTypeNatural, PitchAndFamily.Default, "Sloan")

RtsHelper.BeginScene(texture.GetSurfaceLevel(0), New Viewport(0, 0, 100, 100))

sloanFont.DrawString(Nothing, "A", 1, 1, New SlimDX.Color4())
Return texture
End Function
End Class

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
Followers 0