I've created a subclass of GLKViewController to render some waveforms using GLKBaseEffect which all works fine.
I want to use my own vertex and fragment shaders, so I used the boilerplate code from the default OpenGL Game project. Both shaders compile, link, and are usable. I can alter the color in the vertex shader without issue.
The problem I'm having is passing my own uniforms into the fragment shader. I can pass it to the vertex shader and use it there, but when I declare the same variable in the
Code:
// Vertex shader
attribute vec4 position;
uniform float amplitudeMax;
void main() {
gl_Position = position + amplitudeMax; // This works and offsets the drawing
}
// Fragment shader
uniform float amplitudeMax; // Fails to compile
//uniform float amplitudeMax; // Compiles fine
void main()
{
gl_FragColor = vec4(0.0, 0.0, 1.0, 1.0);
}
If curious, here is how I set up the uniforms and shaders
func loadShaders() -> Bool {
// Copied from default OpenGL Game project
// link program ...
uniforms[UNIFORM_AMPLITUDE_MAX] = glGetUniformLocation(program, "amplitudeMax")
// release shaders ...
}
// The draw loop
func render() {
configureShaders()
// ... draw
}
func configureShaders() {
glUseProgram(program)
let max = AudioManager.sharedInstance.bufferManager.currentPower)
glUniform1f(uniforms[UNIFORM_AMPLITUDE_MAX], max)
}
I had another idea of passing the value from the vertex shader to the fragment shader using a varying float. Again I can declare and use the variable in the vertex shader but delaring it in the fragment shader cause it to fail compiling.
Edit: --------------------------------------------------
Through trial and error I found that if (in my fragment shader) qualify my uniform declaration with a precision that it works for both uniforms and varying (can pass from vertex to shader).
uniform lowp float amplitudeMax;
void main() {
gl_FragColor = vec4(amplitudeMax, 0.0, 1.0, 1.0);
}
