String8 ProgramCache::generateFragmentShader(const Key& needs) {
Formatter fs;
if (needs.getTextureTarget() == Key::TEXTURE_EXT) {
fs << "#extension GL_OES_EGL_image_external : require";
}
// default precision is required-ish in fragment shaders
fs << "precision mediump float;";
if (needs.getTextureTarget() == Key::TEXTURE_EXT) {
fs << "uniform samplerExternalOES sampler;"
<< "varying vec2 outTexCoords;";
} else if (needs.getTextureTarget() == Key::TEXTURE_2D) {
fs << "uniform sampler2D sampler;"
<< "varying vec2 outTexCoords;";
} else if (needs.getTextureTarget() == Key::TEXTURE_OFF) {
fs << "uniform vec4 color;";
}
if (needs.hasPlaneAlpha()) {
fs << "uniform float alphaPlane;";
}
if (needs.hasColorMatrix()) {
fs << "uniform mat4 colorMatrix;";
}
fs << "void main(void) {" << indent;
if (needs.isTexturing()) {
fs << "gl_FragColor = texture2D(sampler, outTexCoords);";
} else {
fs << "gl_FragColor = color;";
}
if (needs.isOpaque()) {
fs << "gl_FragColor.a = 1.0;";
}
if (needs.hasPlaneAlpha()) {
// modulate the alpha value with planeAlpha
if (needs.isPremultiplied()) {
// ... and the color too if we're premultiplied
fs << "gl_FragColor *= alphaPlane;";
} else {
fs << "gl_FragColor.a *= alphaPlane;";
}
}
if (needs.hasColorMatrix()) {
if (!needs.isOpaque() && needs.isPremultiplied()) {
// un-premultiply if needed before linearization
fs << "gl_FragColor.rgb = gl_FragColor.rgb/gl_FragColor.a;";
}
fs << "gl_FragColor.rgb = pow(gl_FragColor.rgb, vec3(2.2));";
fs << "gl_FragColor = colorMatrix*gl_FragColor;";
fs << "gl_FragColor.rgb = pow(gl_FragColor.rgb, vec3(1.0 / 2.2));";
if (!needs.isOpaque() && needs.isPremultiplied()) {
// and re-premultiply if needed after gamma correction
fs << "gl_FragColor.rgb = gl_FragColor.rgb*gl_FragColor.a;";
}
}
fs << dedent << "}";
return fs.getString();
}
String8 ProgramCache::generateVertexShader(const Key& needs) {
Formatter vs;
if (needs.isTexturing()) {
vs << "attribute vec4 texCoords;"
<< "varying vec2 outTexCoords;";
}
vs << "attribute vec4 position;"
<< "uniform mat4 projection;"
<< "uniform mat4 texture;"
<< "void main(void) {" << indent
<< "gl_Position = projection * position;";
if (needs.isTexturing()) {
vs << "outTexCoords = (texture * texCoords).st;";
}
vs << dedent << "}";
return vs.getString();
}