GLSL shader crash only on samsung galax s3

cocos2d-x
1

Hi to everyone,

I have this fragment shader .

varying vec4 v_fragmentColor;
varying vec2 v_texCoord;

uniform float u_percent;

void main()
{
const float alpha = atan(v_texCoord.y - 0.5f, v_texCoord.x - 0.5f);
gl_FragColor = vec4(alpha,alpha,alpha, 1.f) * v_fragmentColor * texture2D(CC_Texture0, v_texCoord) ;
}

This shader works on Windows and ExperiaZ3 (Android 5.1), but crash on Samsung Galaxy S3 (Android 4.3).
I have assumption, it’s because atan function, but i don’t know how to fix it.

2

Hello, the problem comme from the const. Its à bad use of the word const. Rénové it and after this it supposée to work correctly

Regards

3

Hi, i try to remove const , but still doesn’t work. :frowning:
After short research i found this:
OpenGL ES 3.0 - This API specification is supported by Android 4.3 (API level 18) and higher.
And this
https://www.opengl.org/sdk/docs/man/html/atan.xhtml.

But still can’t found solution.

Regards.

4

atan is part of the opengl es 2 also. i have this is a sahder of mine for the android 2.2…

for many driver, define a const var by a function or an operation cause porblem. the const must be used only for define literal value.

if this is not that, i dont know what it can be due to.

have you tried the shader without atan. with a self defined value ? maybe the probleme not come from atan

regards

5

Actually this is full version of my shader. For cooldown.

varying vec4 v_fragmentColor;
varying vec2 v_texCoord;

uniform float u_percent;

void main()
{
float angle = atan(v_texCoord.y - 0.5f, v_texCoord.x - 0.5f) + 3.14159265359f ;
if(angle < 6.28318530718f * u_percent)
gl_FragColor = texture2D(CC_Texture0, v_texCoord);
else
{
float min = 0.1;
float max = 0.5;
float diff = max - min;

float coef = min  + (max - min) * u_percent;
  gl_FragColor = vec4(coef, coef, coef, 1.) * texture2D(CC_Texture0, v_texCoord);

}
}

I remove all consts but still doesn’t work for leveno A536 with Android 4.4.2 and Samsung S3

6

I found were is my problem. Maybe old phone support only halfs. And when we have something like float a = 0.1f; cant compile it. So solution is just remove f -> “float a = 0.1;”

7

yep the f is not part of the glsl syntax. on windows there is a transtype of glsl to directx by angle so the problem not appear systematically. but in fact this kind of syntax error might cause error in log not crash.

its weird

8

if you want to be sure that your syntax is good,
you can check your shader with a offline tool like this soft http://www.funparadigm.com/xshade/ by select the GLES mode

9

There are addons depending on the IDE you are using that have code highlighting and error detection for GLSL. The reason there is no f in glsl is because all values are assumed to be float. The gpu only deals with floats, it’s specifically optimized for float operations/calculations.