# All Questions

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9 views

### Post-processing recommendations for PBR

I've implemented a PBR. It's good but I want it to look more realistic. Since I haven't applied any post-processing I feel like there's more room to improve in that direction. What kind of post-...
19 views

### Blur algorithms that don't use gaussian distribution?

Are there any blurring algorithms other than don't use a gaussian distribution matrix? I heard about an approximation of gaussian blur, with a lower quality and different name, but I don't remember ...
14 views

### Projection of line which lies in an auxiliary inclined plane

A line PQ is 75 mm long and lies in an auxiliary inclined plane (A.I.P.) which makes an angle of 45° with the H.P. The front view of the line measures 55 mm and the end P is in the V.P. and 20 mm ...
8 views

### OpenGL ignores glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

I'm learning OpenGL for a personal project. I need to draw a triangle mesh as a wireframe. From what I've read, I can do this using glPolygonMode. However, the program always draws my polygons filled. ...
14 views

### Are certain solid colors more likely to survive texture compression unchanged?

I have encountered two solid grey textures, #303030 and #1b1b1b, being put through texture compression and coming out as #313031 (changed) and #1b1b1b (unchanged), presumably due to the 32-bit (8:8:8) ...
53 views

### Rendering equation - brdf / pdf > 1?

I am creating a path tracer and I got some strange results when calculating the strength of light. I am using a rendering equation inspired by this diagram: When I use the cosine everything gets ...
27 views

### How do I view my vertex colors that I specified through the texture I've applied on my objec [OpenGL]?

I thought that if I used an image with a transparent background, I would still be able to see the colors I had specified in my vertex attribute buffer. ...
32 views

### 2D signed distance field circle by two triangles, how to angle limit?

I have a square rendered by two triangles (4 vertices and 6 indices), each vertex is located at corner and have it's signed distance field. So vertices have next [position, signed distance field]: ...
37 views

### Compute shader workgroups execution and size [closed]

I want to clarify how are workgroups executed on various GPUs, thus I have several questions. I know that different GPU architectures work differently, but I expect an answer YES if there is single (...
30 views

### Sparse voxel oct tree tracing, optimization tricks?

I have a working oct-ree raytracer and I am applying it to the sponza. The algorithm I have designed works like this at a high level: Collide with the bounding box of the model, move your ray to that ...
24 views

### Opengl GLSL binding locations confusion

The background of this question is that I am trying to write an automatic binding system, where for each uniform variable I want to declare in my GLSL code, I call a method ...
52 views

### Should I learn graphics rendering from scratch or it is ok to go for graphics API? [closed]

I'd like to transition from software engineering to graphics programming, so in the past few weeks I've been creating a path to follow and studying 3D math. My next step is to go for graphics APIs ...
77 views

### How are point and pure directional lights sampled in an unbiased path tracer?

To perform importance sampling on a light source, a probability density function must be provided for the sampling distribution. For most light sources, a valid probability distribution can be found, ...
49 views

### Are virtual point lights in many-light global illumination the same light probes?

There are several papers like this one here that refer to a concept called many-light global illumination using Virtual Point Lights (VPL). That is, the problem of global illumination is reduced to a ...
46 views

### Precision problems when rendering whole planets

I'm trying to implement a camera, which is able to go very close to a planet/moon surface, without flickering surface. The problem: Right now the position of a planet / moon is saved at the center of ...
32 views

### Gamma Correction vs Color Picker

I have some confusion regarding gamma correction and the output of my shaders. I'll start with the setup, then explain my current understanding of the matter, and finally the question. Setup I'm ...
25 views

### How is Unreal's 2D Blendspace implemented?

I'm currently trying to implement animation blending. Or more specifically, parametric animation. Unreal Engine has this in the form of blendspaces. After some experimentation, I've noticed that they ...
61 views

### vulkan perspective matrix vs opengl perspective matrix

Hi I have a slight confusion in using the opengl perspective matrix in vulkan. glm's perspective matrix works directly in vulkan just by multiplying the "[1,1 term by -1 but when I compared the ...
58 views

### Historically Significant 3D Bicubic Patch Data?

The little milk pitcher / jug in Ed Catmull's 1975 PhD thesis “The Utilization of Procedure Models in Digital Image Synthesis”, does anybody have the bicubic patch data for it? The teapot's data (in ...
74 views

### 2d gpu powered rendering engine

First of all I am not sure if this is the correct place to ask my question. If it is not please be so kind to point me in a direction where my question is relevant. A while ago I came across this ...
60 views

### Next Event Estimation for Triangle-based Light Sources

I have a question regarding the NEE for light sources that are composed from triangles. I implemented the next event estimation (explicit light source sampling) for spherical light sources but after ...
22 views

### DX12 resource transition barriers not working

I am facing quite an odd issue trying to create a texture in dx12 via directxTex.Everything works well but after I upload my texture data I place a transition barrier to transition my barrier to be ...
56 views

### OpenGL old-style diffuse shading producing unexpected effects

Question: What is going wrong with the shape of the contours of constant illumination in the below picture ? Detail: Although Lambertian shading might be ill-regarded because it exposes the hard edges ...
28 views

### Shift hue/adjust chroma in CIE Lab space using GLSL

It is possible to implement the CIE Lab/XYZ color space in GLSL, to shift the hue/change chroma of colors/images? Does it require compute shaders?
108 views

### Specular reflection with different viewing direction where reflection direction and viewing direction coincide

Suppose $P_1$ and $P_2$ two different points on surface. And let $l$: be the light source direction, $n$: normal vector $r$: specular reflection direction $v$: viewing direction . In case 1 (at $P_1$...
65 views

### Is drawing Bezier curve with scanline algorithm possible with Vulkan?

As an information, Vulkan is a low-level abstraction layer thru modern GPU. It allows programmers to program the GPU and assemble rendering pipeline. On that pipeline, there are modules of program ...
58 views

### Achieving bokeh blur with custom shapes

I have a 2D texture, without any depth maps, which I'd like to blur to achieve a bokeh effect. The catch, however, is that I want the effect to be custom bitmaps/shapes (e.g. a heart). Here's a part ...
40 views

### Extrude from line and find intersection points

Hey Im currently learning about geometry and vectors and was trying to build a room builder with three js. I basicly create walls from two points (p1, p2). I draw a line and extrude the line to a ...
58 views

### Relationship between probability densities

I'm reading section 8.2 of Eric Veach's thesis, in regards to the relationship between probability densities per solid angle vs projected solid angle: \frac{dP}{d\sigma^\perp}(w_o) = \frac{dP}{d\...
37 views

### [Subsurface Scattering]What's the meaning of diffuse coefficient Rd in bssrdf

Recently, i am reading the papaer A Practical Model for Subsurface Light Transport . I have understand the radiative transport equation : and the approximation of the diffusion equation: . In BRDF ...
61 views

### OpenGL in CodeBlocks with GNU GCC compiler not recognising some constants

I am writing basic code to; draw triangles, lines etc; to translate and orient them, and to project them in perspective, solving the occlusion problem using the depth buffer. Having had success with a ...
42 views

### What problem of my bsdf?

This is a image of microfacetdieletric. But i can not find the problem. My code is : ...
67 views

### Why my bsdf can not pass Chi2test?

I implemented a MicrofacetTransmission in nori. But it can not pass all Chi2test when alpha is large(>= 0.4 or ?),part of chi2test is passed.And I can not found the problem.Can someone help me? ...
43 views

### [Subsurface Scattering]Reflection from Layered Surfaces due to Subsurface Scattering

Recently, I am doing some research about subsurface scattering. i am a little confused about the backscattered radiance mentioned in this paper Reflection from Layered Surfaces due to Subsurface ...
55 views

### What to do with reflected rays that don't intersect?

I implemented reflection on my ray tracer. I had very few objects in the scene, so the reflected rays would less likely intersect. If most of the rays don't intersect, metallic objects would appear ...
110 views

### OpenGL: read texture mipmap level 0 and render to same texture mipmap level 1

I am trying to generate mipmaps, which are based on depthbuffer values. To generate the next mipmap level, I am trying to read in the 4 pixels of the upper mipmap level per pixel. Unlike the usual ...
20 views

After defining an attribute pointer, why can't I just reuse it? I have a VAO bound so shouldn't it just accept the AttributePointer I defined with the last VAO? ...
57 views

I am writing a raytracer which is meant to support shadows. Previously, I have naively implemented hard shadows by casting a shadow ray towards the light (+ offset) and seeing if it hits anything ...
36 views

### Using Perspective Rendering To Render A 3D Point

I am wondering how I can use perspective rendering to render a point onto a screen. An image showing perspective rendering: Say I have a 3d point (with x, y, and z coordinates), a point for the ...
40 views

### Which provides better intuition: THREE.Geometry or THREE.BufferGeometry?

THREE.js recently dropped support for THREE.Geometry in favor of exclusively THREE.BufferGeometry. I'm trying to decide which paradigm to teach in my computer graphics course to best provide students ...
34 views

### Extrusion Algorithm For Bezier Curves

I just posted this to SO but the question got closed, so I hope it's OK if I try it again here. They say "we don’t allow questions seeking recommendations for books, tools, software libraries&...
39 views

### Image made of shapes - terminology + software? [closed]

I've often seen images that look like the following example Q1) is there a term for such an image? Q2) What common software is used to convert a real photo (e.g. human face) to be composed of such ...
123 views

### Confusion about HDR image pipeline

I am working on a path tracing renderer, and I want to produce an sRGB image out of the HDR image buffer I get at the end of my rendering algorithm. Up until now I have worked just by clamping values, ...
26 views

### split Depthbuffer values to distance

My scenario is a Solar system with satellites. Therefor objects can be very close to the camera while a planet for example is in background far away. This setup causes problems with the depthbuffer ...
32 views

### Why Bresenham's circle drawing algorithm sets "3-2R" as the initial value of decision parameter?

I know the most precise initial value is 1.25-R, then we can double this which will not change the result. But we don't like the float number, so we use the integer ...
57 views

### How to use maximum resolution (pixel density) with OpenGL in MS Windows

CodeBlocks offers an example program in C, that uses OpenGL. It draws a single multicoloured rotating triangle. I have been building on this example. I am a novice in C and in OpenGL. I believe that I ...
37 views

### Does automatic UV unwrapping work with an indexed face set model?

When working with Graphics APIs like OpenGL its common to use an index face set model. That is, multiple faces share adjacent / overlapping vertices by using a list of indices. Most game engines like ...
41 views

### Are intersections still hardware accelerated if we define a custom intersection program in Optix?

I've stumbled into Optix samples that define their own intersection programs to define how primitives intersect (or don't) with a ray, and others (mostly those only dealing with triangle meshes) that ...