Generating a three-dimensional object

Apparatus for generating a three-dimensional object, comprising:

• a build material distributor to provide a first layer of build material on a build material support, and to provide subsequent layers of build material on a previously provided layer of build material;
• a first agent distributor to selectively deliver a coalescing agent onto portions of a layer of build material;
• a second agent distributor to selectively deliver a coalescence modifier agent onto portions of a layer of build material;
• an energy source to apply energy to build material;
• and
• a controller to:
• control the build material distributor to provide a layer of build material;
• control the agent distributors to selectively deliver each of the agents onto a layer of build material in respective patterns derived from data representing a slice of a three-dimensional object to be generated, the patterns to cause, upon application of energy to the layer of build material, an object to have properties dependent on the patterns by causing portions of the layer on which only coalescing agent is delivered or penetrates to heat up above the melting point of the build material and coalesce, and portions of the layer on which only coalescence modifier agent is delivered or penetrates not to heat up above the melting point of the build material and not to coalesce;
• and
• control the energy source to apply energy to the layer of build material.