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
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
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
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
but I still don’t know whether or not the gl_FragCoord.z is linear. Whether gl_FragCoord.z is linear or not depends on, the projection matrix. While for Orthographic Projection gl_FragCoord.z is linear, for Perspective Projection it is not linear. In general, the depth (gl_FragCoord.z and gl_FragDepth) is calculated as follows (see GLSL gl_FragCoord.z Calculation and Setting gl_FragDepth): … Read more
+1 for interesting problem. Was curious so I tried to code this. I need the use of arrays so I chose #version 420 core. My app is rendering single quad covering screen with coordinates <-1,+1>. I am using whole ASCII 8×8 pixel 32×8 characters font texture I created some years ago: The vertex is simple: … Read more
I am using something similar to that answer linked by @RetoKoradi comment but I got double layered transparent models with textures (glass with both inner and outer surface) with fully solid machinery and stuff around. For such scenes I am using also multi pass approach and the Z-sorting is done by sequence of setting front … Read more