import { UnsignedByteType } from "three";

import { Pass } from "./Pass";

/**

* A shader pass.

*

* Renders any shader material as a fullscreen effect. This pass should not be used to create multiple chained effects.

* For a more efficient solution, please refer to the {@link EffectPass}.

*/

export class ShaderPass extends Pass {

/**

* Constructs a new shader pass.

*

* @param {ShaderMaterial} material - A shader material.

* @param {String} [input="inputBuffer"] - The name of the input buffer uniform.

*/

constructor(material, input = "inputBuffer") {

super("ShaderPass");

this.fullscreenMaterial = material;

/**

* The input buffer uniform.

*

* @type {String}

* @private

*/

this.inputBufferUniform = null;

this.setInput(input);

}

/**

* Sets the name of the input buffer uniform.

*

* Most fullscreen materials modify texels from an input texture. This pass automatically assigns the main input

* buffer to the uniform identified by the given name.

*

* @param {String} input - The name of the input buffer uniform.

*/

setInput(input) {

this.inputBufferUniform = null;

if(this.fullscreenMaterial !== null) {

const uniforms = this.fullscreenMaterial.uniforms;

if(uniforms !== undefined && uniforms[input] !== undefined) {

this.inputBufferUniform = uniforms[input];

}

}

}

/**

* Renders the effect.

*

* @param {WebGLRenderer} renderer - The renderer.

* @param {WebGLRenderTarget} inputBuffer - A frame buffer that contains the result of the previous pass.

* @param {WebGLRenderTarget} outputBuffer - A frame buffer that serves as the output render target unless this pass renders to screen.

* @param {Number} [deltaTime] - The time between the last frame and the current one in seconds.

* @param {Boolean} [stencilTest] - Indicates whether a stencil mask is active.

*/

render(renderer, inputBuffer, outputBuffer, deltaTime, stencilTest) {

if(this.inputBufferUniform !== null && inputBuffer !== null) {

this.inputBufferUniform.value = inputBuffer.texture;

}

renderer.setRenderTarget(this.renderToScreen ? null : outputBuffer);

renderer.render(this.scene, this.camera);

}

/**

* Performs initialization tasks.

*

* @param {WebGLRenderer} renderer - A renderer.

* @param {Boolean} alpha - Whether the renderer uses the alpha channel.

* @param {Number} frameBufferType - The type of the main frame buffers.

*/

initialize(renderer, alpha, frameBufferType) {

if(frameBufferType !== undefined && frameBufferType !== UnsignedByteType) {

this.fullscreenMaterial.defines.FRAMEBUFFER_PRECISION_HIGH = "1";

}

}

}