Earlier I said something along the lines of..
.. need to be seriously looking at tweeking the actual shader code with many of these
difficult shaders, rather than just editing the scn code..
Today i was converting a WebGL shader to run on our OpenGL (fullscreen player).
When I subsequently ran that shader in a fullscreen scene, the model movements were so badly
stilted..movement was so jerky & stuttering. Unuseable I thought :-(
In the .scn I tried deploying a quad instead of a mounting texture.
Tried reducing the size of shader's mounting texture using a frame buffer.
Tried just about everything I could think of ..to relieve the jerkiness of the model.
The solution to all of this (after a lot of searching) lay mainly in the .fsh coding.
The shader author had left in the code pre-amble comments:
//Decrease or comment out to decrease/disable anti-aliasing (faster)
//#define AA_SCALE 2.0
//Comment out to disable lighting (faster)
//#define MODE_LIT
So I left these lines // commented out, thinking that was enough for our platform
to disregard any extra subsequent processing involving AA_SCALE and MODE_LIT
however the jerky-ness of the models persisted just as badly as ever.
It wasn't until going through the body of the .fsh code, & commenting out all the #ifdef
conditional statements relating to AA_SCALE or MODE_LIT that the movements of the models
began to free up until finally they were all moving as normal. Commenting out the #defines alone was insufficient.
Commenting out the boolean in this case was like this shown below..
/* #ifdef AA_SCALE
float done = 0.0;
for(float aaX = -AA_SCALE; aaX < AA_SCALE; aaX++) {
for(float aaY = -AA_SCALE; aaY < AA_SCALE; aaY++) {
uv = (2.0*(gl_FragCoord.xy + (vec2(aaX, aaY)/AA_SCALE)) - iResolution.xy) / iResolution.y;
dir = vec3(uv, -1);
#endif
*/
.......and
/* #ifdef MODE_LIT
color = color*7.0*dot(normalize(p-vec3(0,0,5)), estNormal(p));
#endif
*/
So I thought to share that ,by tweeking the .fsh code to remove unnecessary '#ifdef' a lot appears to be
achieveable to make some fragment shaders useable, yet less taxing on models' movements. Hope thats helpful.
