OpenGL Insights

626 VII Software Design

uniform sampler2D tex;

out vec4 fragColor;

void main ()

{

vec2 curPos ;

curPos .x = float (int( gl_FragCoord.x) % 32) / 32.0;

curPos .y = float (int( gl_FragCoord.y) % 32) / 32.0;

vec4 color = texture (tex , curPos );

if ( color.w < 0.5)

{

discard ;

}

fragColor = color;

}

Listing 43.5. Polygon stipple fragment shader.

in the shader main. The remainder operator (%) is illegal in GLSL ES, so the texture

coordinate computation would also need to be adjusted accordingly.

43.3 Keeping Code Maintainable across API

Variants

After a code base is ported to a modern core profile of OpenGL, there is still some

work needed to ensure compatibility with ...