IOS shader differences

Question

I study 3D programming with the book Learning Modern 3D Graphics Programming , but I was out of luck with shaders and GLES 2.0 on iOS. I am working with the opengl xcode 4 game template, although the changes make sense for the first example in the book.

The first shaders in the book will not compile with many different errors. First vertex shader

#version 330 layout(location = 0) in vec4 position; void main() { gl_Position = position; } 

He complains about the version approval and refuses to allow the use of the layout as a specifier. I finally managed to create this.

 attribute vec4 position; void main() { gl_Position = position; } 

Again, the first fragment shader refuses to build due to the version and will not allow output in the global segment

 #version 330 out vec4 outputColor; void main() { outputColor = vec4(1.0f, 1.0f, 1.0f, 1.0f); } 

With an error

 ERROR: 0:10: Invalid qualifiers 'out' in global variable context 

Ok, so I managed to get the first example (a simple triangle) for working with the following shaders.

vertex shader

 #version 100 void main() { gl_FragColor = vec4(1.0,1.0,1.0,1.0); } 

fragment shader

 attribute vec4 position; void main() { gl_Position = position; } 

So, they worked, and I tried the first color example in the next chapter.

 #version 330 out vec4 outputColor; void main() { float lerpValue = gl_FragCoord.y / 500.0f; outputColor = mix(vec4(1.0f, 1.0f, 1.0f, 1.0f), vec4(0.2f, 0.2f, 0.2f, 1.0f), lerpValue); } 

Even working with fixed problems from the eariler, the version, f in the floats is not resolved, the shader still refuses to build with this error

 ERROR: 0:13: 'float' : declaration must include a precision qualifier for type 

In fact, he complains about the float.

I tried a Google search to find an explanation of the differences, but none of them appeared. I also read apple documents that were looking for advice and did not find any help. I'm not sure where else to look, or what I'm really doing wrong.

Answer 1

add this at the top of the shader: precision mediump float;

or precision highp float;

Depends on your needs.