protected void setupBlending(int mode) {
blendMode = mode;
if (blendMode == REPLACE) {
gl.glBlendEquation(GL.GL_FUNC_ADD);
gl.glBlendFunc(GL.GL_ONE, GL.GL_ZERO);
} else if (blendMode == BLEND) {
gl.glBlendEquation(GL.GL_FUNC_ADD);
gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);
} else if (blendMode == ADD) {
gl.glBlendEquation(GL.GL_FUNC_ADD);
gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE);
} else if (blendMode == SUBTRACT) {
gl.glBlendEquation(GL.GL_FUNC_ADD);
gl.glBlendFunc(GL.GL_ONE_MINUS_DST_COLOR, GL.GL_ZERO);
} else if (blendMode == LIGHTEST) {
gl.glBlendEquation(GL.GL_MAX);
gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_DST_ALPHA);
} else if (blendMode == DARKEST) {
gl.glBlendEquation(GL.GL_MIN);
gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_DST_ALPHA);
} else if (blendMode == DIFFERENCE) {
gl.glBlendEquation(GL.GL_FUNC_REVERSE_SUBTRACT);
gl.glBlendFunc(GL.GL_ONE, GL.GL_ONE);
} else if (blendMode == EXCLUSION) {
gl.glBlendEquation(GL.GL_FUNC_ADD);
gl.glBlendFunc(GL.GL_ONE_MINUS_DST_COLOR, GL.GL_ONE_MINUS_SRC_COLOR);
} else if (blendMode == MULTIPLY) {
gl.glBlendEquation(GL.GL_FUNC_ADD);
gl.glBlendFunc(GL.GL_DST_COLOR, GL.GL_SRC_COLOR);
} else if (blendMode == SCREEN) {
gl.glBlendEquation(GL.GL_FUNC_ADD);
gl.glBlendFunc(GL.GL_ONE_MINUS_DST_COLOR, GL.GL_ONE);
} else if (blendMode == BACKGROUND_ALPHA) {
gl.glBlendColor(0.0f, 0.0f, 0.0f, 1.0f);
gl.glBlendFunc(GL.GL_ONE, GL.GL_CONSTANT_COLOR);
}
// HARD_LIGHT, SOFT_LIGHT, OVERLAY, DODGE, BURN modes cannot be implemented
// in fixed-function pipeline because they require conditional blending and
// non-linear blending equations.
}
