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By Gnollrunner
Hi again, After some looking around I have decided to base my game directly on Direct X rather than using an existing game engine. Because of the nature of the stuff I'm doing it just didn't seem to fit very well and I kept running into road blocks. At this point I have a big blob of code for doing fractal world generation and some collision code, and I'm trying to put it into some form that resembles a game engine. Since I've never used one before It's a bit alien to me ..... so can someone direct me to a book, website, article, whatever... that covers this? I'm mainly looking for stuff that covers C++ library design. I'm not adverse to using 3rd party tools for stuff I can used them for.

By mmmax3d
Hi everyone,
I would need some assistance from anyone who has a similar experience
or a nice idea!
I have created a skybox (as cube) and now I need to add a floor/ground.
The skybox is created from cubemap and initially it was infinite.
Now it is finite with a specific size. The floor is a quad in the middle
of the skybox, like a horizon.
I have two problems:
When moving the skybox upwards or downwards, I need to
sample from points even above the horizon while sampling
from the botton at the same time. I am trying to create a seamless blending of the texture
at the points of the horizon, when the quad is connected
to the skybox. However, I get skew effects. Does anybody has done sth similar?
Is there any good practice?
Thanks everyone!

By mmmax3d
Hi everyone,
I would need some assistance from anyone who has a similar experience
or a nice idea!
I have created a skybox (as cube) and now I need to add a floor/ground.
The skybox is created from cubemap and initially it was infinite.
Now it is finite with a specific size. The floor is a quad in the middle
of the skybox, like a horizon.
I have two problems:
When moving the skybox upwards or downwards, I need to
sample from points even above the horizon while sampling
from the botton at the same time. I am trying to create a seamless blending of the texture
at the points of the horizon, when the quad is connected
to the skybox. However, I get skew effects. Does anybody has done sth similar?
Is there any good practice?
Thanks everyone!

By iArtist93
I'm trying to implement PBR into my simple OpenGL renderer and trying to use multiple lighting passes, I'm using one pass per light for rendering as follow:
1 First pass = depth
2 Second pass = ambient
3 [3 .. n] for all the lights in the scene.
I'm using the blending function glBlendFunc(GL_ONE, GL_ONE) for passes [3..n], and i'm doing a Gamma Correction at the end of each fragment shader.
But i still have a problem with the output image it just looks noisy specially when i'm using texture maps.
Is there anything wrong with those steps or is there any improvement to this process?

By chiffre
Introduction:
In general my questions pertain to the differences between floating and fixedpoint data. Additionally I would like to understand when it can be advantageous to prefer fixedpoint representation over floatingpoint representation in the context of vertex data and how the hardware deals with the different datatypes. I believe I should be able to reduce the amount of data (bytes) necessary per vertex by choosing the most opportune representations for my vertex attributes. Thanks ahead of time if you, the reader, are considering the effort of reading this and helping me.
I found an old topic that shows this is possible in principal, but I am not sure I understand what the pitfalls are when using fixedpoint representation and whether there are any hardwarebased performance advantages/disadvantages.
(TLDR at bottom)
The Actual Post:
To my understanding HLSL/D3D11 offers not just the traditional floating point model in half,single, and doubleprecision, but also the fixedpoint model in form of signed/unsigned normalized integers in 8,10,16,24, and 32bit variants. Both models offer a finite sequence of "gridpoints". The obvious difference between the two models is that the fixedpoint model offers a constant spacing between values in the normalized range of [0,1] or [1,1], while the floating point model allows for smaller "deltas" as you get closer to 0, and larger "deltas" the further you are away from 0.
To add some context, let me define a struct as an example:
struct VertexData { float[3] position; //3x32bits float[2] texCoord; //2x32bits float[3] normals; //3x32bits } //Total of 32 bytes Every vertex gets a position, a coordinate on my texture, and a normal to do some light calculations. In this case we have 8x32=256bits per vertex. Since the texture coordinates lie in the interval [0,1] and the normal vector components are in the interval [1,1] it would seem useful to use normalized representation as suggested in the topic linked at the top of the post. The texture coordinates might as well be represented in a fixedpoint model, because it seems most useful to be able to sample the texture in a uniform manner, as the pixels don't get any "denser" as we get closer to 0. In other words the "delta" does not need to become any smaller as the texture coordinates approach (0,0). A similar argument can be made for the normalvector, as a normal vector should be normalized anyway, and we want as many points as possible on the sphere around (0,0,0) with a radius of 1, and we don't care about precision around the origin. Even if we have large textures such as 4k by 4k (or the maximum allowed by D3D11, 16k by 16k) we only need as many gridpoints on one axis, as there are pixels on one axis. An unsigned normalized 14 bit integer would be ideal, but because it is both unsupported and impractical, we will stick to an unsigned normalized 16 bit integer. The same type should take care of the normal vector coordinates, and might even be a bit overkill.
struct VertexData { float[3] position; //3x32bits uint16_t[2] texCoord; //2x16bits uint16_t[3] normals; //3x16bits } //Total of 22 bytes Seems like a good start, and we might even be able to take it further, but before we pursue that path, here is my first question: can the GPU even work with the data in this format, or is all I have accomplished minimizing CPUside RAM usage? Does the GPU have to convert the texture coordinates back to a floatingpoint model when I hand them over to the sampler in my pixel shader? I have looked up the data types for HLSL and I am not sure I even comprehend how to declare the vertex input type in HLSL. Would the following work?
struct VertexInputType { float3 pos; //this one is obvious unorm half2 tex; //half corresponds to a 16bit float, so I assume this is wrong, but this the only 16bit type I found on the linked MSDN site snorm half3 normal; //same as above } I assume this is possible somehow, as I have found input element formats such as: DXGI_FORMAT_R16G16B16A16_SNORM and DXGI_FORMAT_R16G16B16A16_UNORM (also available with a different number of components, as well as different component lengths). I might have to avoid 3component vectors because there is no 3component 16bit input element format, but that is the least of my worries. The next question would be: what happens with my normals if I try to do lighting calculations with them in such a normalizedfixedpoint format? Is there no issue as long as I take care not to mix floating and fixedpoint data? Or would that work as well? In general this gives rise to the question: how does the GPU handle fixedpoint arithmetic? Is it the same as integerarithmetic, and/or is it faster/slower than floatingpoint arithmetic?
Assuming that we still have a valid and useful VertexData format, how far could I take this while remaining on the sensible side of what could be called optimization? Theoretically I could use the an input element format such as DXGI_FORMAT_R10G10B10A2_UNORM to pack my normal coordinates into a 10bit fixedpoint format, and my verticies (in object space) might even be representable in a 16bit unsigned normalized fixedpoint format. That way I could end up with something like the following struct:
struct VertexData { uint16_t[3] pos; //3x16bits uint16_t[2] texCoord; //2x16bits uint32_t packedNormals; //10+10+10+2bits } //Total of 14 bytes Could I use a vertex structure like this without too much performanceloss on the GPUside? If the GPU has to execute some sort of unpacking algorithm in the background I might as well let it be. In the end I have a functioning deferred renderer, but I would like to reduce the memory footprint of the huge amount of vertecies involved in rendering my landscape.
TLDR: I have a lot of vertices that I need to render and I want to reduce the RAMusage without introducing crazy compression/decompression algorithms to the CPU or GPU. I am hoping to find a solution by involving fixedpoint datatypes, but I am not exactly sure how how that would work.


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