What is it about shaders that even potentially makes if statements performance problems? It has to do with how shaders get executed and where GPUs get their massive computing performance from. Separate shader invocations are usually executed in parallel, executing the same instructions at the same time. They’re simply executing them on different sets of … Read more
the problem is that you store non linear values which are truncated so when you peek the depth values later on you got choppy result because you lose accuracy the more you are far from znear plane. No matter what you evaluate you will not obtain better results unless: Lower accuracy loss You can change … Read more
There are currently 4 ways to do this: standard 1D textures, buffer textures, uniform buffers, and shader storage buffers. 1D Textures With this method, you use glTex(Sub)Image1D to fill a 1D texture with your data. Since your data is just an array of floats, your image format should be GL_R32F. You then access it in … Read more
You might be interested in having a look at ShaderGen. From the description: ShaderGen is a program that can automatically produce shaders that mimic the results of a set of fixed function state. This tool was used to verify the fixed function shader code that is described in Chapter 9. By the way, you will … Read more
Lambertian reflectance model To model the reflection of light in computer graphics is used a Bidirectional reflectance distribution function (BRDF). BRDF is a function that gives the relation between the light reflected along an outgoing direction and the light incident from an incoming direction. A perfect diffuse surface has a BRDF that has the same … Read more
Background map Ok I created a test RGBA map as 2 images one containing RGB (on the left) and second with the alpha channel (on the right) so you can see them both. Of coarse they are combined to form single RGBA texture. I blurred them both a bit to obtain better visual effects on … Read more
What you need is to search your cubic path and remember closest point. This can be done recursively with increasing precisions here small C++ GL example: //————————————————————————— double pnt[]= // cubic curve control points { -0.9,-0.8,0.0, -0.6,+0.8,0.0, +0.6,+0.8,0.0, +0.9,-0.8,0.0, }; const int pnts3=sizeof(pnt)/sizeof(pnt[0]); const int pnts=pnts3/3; //————————————————————————— double cubic_a[4][3]; // cubic coefficients void cubic_init(double *pnt) … Read more
For very simple pseudorandom-looking stuff, I use this oneliner that I found on the internet somewhere: float rand(vec2 co){ return fract(sin(dot(co, vec2(12.9898, 78.233))) * 43758.5453); } You can also generate a noise texture using whatever PRNG you like, then upload this in the normal fashion and sample the values in your shader; I can dig … Read more
It flows from the definition of a normal. Suppose you have the normal, N, and a vector, V, a tangent vector at the same position on the object as the normal. Then by definition N·V = 0. Tangent vectors run in the same direction as the surface of an object. So if your surface is … Read more
My bet is on the color setting/mixing in fragment shader… you are setting output color more then once If I remember correctly on some gfx drivers that do a big problems for example everything after the line color = vec4(brownColor * (texture(diffuseMap, fsCoords).rgb + 0.25), 1.0);//add a fixed base color (0.25), because its dark as … Read more