question

Hi Cory, Are you still having issues with this? If you could, please share any sample code where you believe issues may be occurring. Thanks, Justin

Thank you for following up! I boiled it down to what I feel is the simplest shader that reproduces the problem: The error during linking is: Results of linking program : 0 ERROR:OPTIMIZER-3 (line 6) Support for for loops is restricted : unable to determine the number of iterations at compile time final String fragmentShader = "precision mediump float; \n" + "varying vec4 v_Color; \n" + "void main() \n" + "{ \n" + " float i; \n" + " for (i=0.; i<1.; i+=0.01) {\n" + " if (i > gl_FragCoord.x/1000.) break;\n" + " } \n" + " gl_FragColor = vec4(i, 1.0, 1.0, 1.0);\n" // vec4(float(gl_FragCoord.x)/a, float(glFragCoord.x)/a, float(gl_FragCoord.x)/a, 1.0); \n" + "} \n"; It does NOT like me bailing out early with the break; The shader executes without the break.

Hi corygiovino, I've seen that there are issues with nested loops having non-constant variables, but your for loop looks fine here. I'll keep looking.

Thank you. I wonder if the optimization level at GLSL link time is configurable.

Since this GPU is the only one I cannot get my source to run on I am looking in here: http://www.broadcom.com/blog/chip-design/android-for-all-broadcom-gives-developers-keys-to-the-videocore-kingdom/ Please let me know if you use this stack on your device for the Capri VideoCore 4. If so Please share you Android.mk so I can attempt to reproduce on my end.

Control flow inside GLSL ES 1.0 shaders has some limitations based on the spec ( https://www.khronos.org/registry/gles/specs/2.0/GLSL_ES_Specification_1.0.17.pdf). See Appendix A #4. According to this, the reason your shader doesn't work with the break, is because the break is a non-constant conditional within the loop. *Most* GPU drivers don't adhere to this, and will allow any sort of control flow within a shader. However, the Broadcom driver isn't the only one that doesn't allow it. Older Adreno drivers, would also fail to compile shaders like this one.