The GL backend passes a uniform 3x3 matrix to a uniform with a name
given by 'transformAttributeName.' This matrix is a transformation
applied to every vertex. Each vertex receives a vec2 of its position
and texture coordinate, given by 'positionAttributeName' and
'texPositionAttributeName.' Vertices also are blended with a color,
given by 'colorAttributeName.' The texture is passed as a uniform
sampler2D to 'textureAttributeName.' The output of the shader is a
vec4 for a color, given by 'colorOutputName'
Set the current shader and its attributes
The GL backend passes a uniform 3x3 matrix to a uniform with a name given by 'transformAttributeName.' This matrix is a transformation applied to every vertex. Each vertex receives a vec2 of its position and texture coordinate, given by 'positionAttributeName' and 'texPositionAttributeName.' Vertices also are blended with a color, given by 'colorAttributeName.' The texture is passed as a uniform sampler2D to 'textureAttributeName.' The output of the shader is a vec4 for a color, given by 'colorOutputName'