RedCore/cocos2d/cocos/3d/CCSkybox.cpp

/****************************************************************************
 Copyright (c) 2015-2017 Chukong Technologies Inc.
 
 http://www.cocos2d-x.org
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
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 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
 
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 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 THE SOFTWARE.
 ****************************************************************************/

#include "base/ccMacros.h"
#include "base/CCConfiguration.h"
#include "base/CCDirector.h"
#include "renderer/ccGLStateCache.h"
#include "renderer/CCGLProgram.h"
#include "renderer/CCGLProgramCache.h"
#include "renderer/CCGLProgramState.h"
#include "renderer/CCRenderer.h"
#include "renderer/CCRenderState.h"
#include "renderer/CCTextureCube.h"
#include "3d/CCSkybox.h"
#include "2d/CCCamera.h"

NS_CC_BEGIN

Skybox::Skybox()
    : _vao(0)
    , _vertexBuffer(0)
    , _indexBuffer(0)
    ,_texture(nullptr)
{
}

Skybox::~Skybox()
{
    glDeleteBuffers(1, &_vertexBuffer);
    glDeleteBuffers(1, &_indexBuffer);

    _vertexBuffer = 0;
    _indexBuffer = 0;

    if (Configuration::getInstance()->supportsShareableVAO())
    {
        glDeleteVertexArrays(1, &_vao);
        GL::bindVAO(0);
        _vao = 0;
    }

    _texture->release();
}

Skybox* Skybox::create(const std::string& positive_x, const std::string& negative_x,
               const std::string& positive_y, const std::string& negative_y,
               const std::string& positive_z, const std::string& negative_z)
{
    auto ret = new (std::nothrow) Skybox();
    ret->init(positive_x, negative_x, positive_y, negative_y, positive_z, negative_z);
    
    ret->autorelease();
    return ret;
}

bool Skybox::init()
{
    // create and set our custom shader
    auto shader = GLProgramCache::getInstance()->getGLProgram(GLProgram::SHADER_3D_SKYBOX);
    auto state = GLProgramState::create(shader);
    state->setVertexAttribPointer(GLProgram::ATTRIBUTE_NAME_POSITION, 3, GL_FLOAT, GL_FALSE, sizeof(Vec3), nullptr);
    setGLProgramState(state);

    initBuffers();

    CHECK_GL_ERROR_DEBUG();

    return true;
}

bool Skybox::init(const std::string& positive_x, const std::string& negative_x,
          const std::string& positive_y, const std::string& negative_y,
          const std::string& positive_z, const std::string& negative_z)
{
    auto texture = TextureCube::create(positive_x, negative_x, positive_y, negative_y, positive_z, negative_z);
    if (texture == nullptr)
        return false;
    
    init();
    setTexture(texture);
    return true;
}

void Skybox::initBuffers()
{
    if (Configuration::getInstance()->supportsShareableVAO())
    {
        glGenVertexArrays(1, &_vao);
        GL::bindVAO(_vao);
    }
	// The skybox is rendered using a purpose-built shader which makes use of
	// the shader language's inherent support for cubemaps. Hence there is no
	// need to build a cube mesh. All that is needed is a single quad that
	// covers the entire screen. The vertex shader will draw the appropriate
	// view of the cubemap onto that quad.
	//
	// The vertex shader does not apply either the model/view matrix or the
	// projection matrix, so the appropriate quad is one with unit coordinates
	// in the x and y dimensions. Such a quad will exactly cover the screen.
	// To ensure that the skybox is rendered behind all other objects, z needs
	// to be 1.0, but the vertex shader overwrites z to 1.0, so - for the sake
	// of z-buffering - it is unimportant what we set it to for the vertices
	// of the quad.
	//
	// The quad vertex positions are also used in deriving a direction
	// vector for the cubemap lookup. We choose z = -1 which matches the
	// negative-z pointing direction of the camera and gives a field of
	// view of 90deg in both x and y, if not otherwise adjusted. That fov
	// is then adjusted to exactly match the camera by applying a prescaling
	// to the camera's world transformation before sending it to the shader.

    // init vertex buffer object
    Vec3 vexBuf[] =
    {
        Vec3(1, -1, -1), Vec3(1, 1, -1), Vec3(-1, 1, -1), Vec3(-1, -1, -1)
    };

    glGenBuffers(1, &_vertexBuffer);
    glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vexBuf), vexBuf, GL_STATIC_DRAW);

    // init index buffer object
    const unsigned char idxBuf[] = {0, 1, 2, 0, 2, 3};

    glGenBuffers(1, &_indexBuffer);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _indexBuffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(idxBuf), idxBuf, GL_STATIC_DRAW);

    if (Configuration::getInstance()->supportsShareableVAO())
    {
        glEnableVertexAttribArray(GLProgram::VERTEX_ATTRIB_POSITION);
        getGLProgramState()->applyAttributes(false);

        GL::bindVAO(0);
    }
}

void Skybox::draw(Renderer* renderer, const Mat4& transform, uint32_t flags)
{
    _customCommand.init(_globalZOrder);
    _customCommand.func = CC_CALLBACK_0(Skybox::onDraw, this, transform, flags);
    _customCommand.setTransparent(false);
    _customCommand.set3D(true);
    renderer->addCommand(&_customCommand);
}

void Skybox::onDraw(const Mat4& transform, uint32_t /*flags*/)
{
    auto camera = Camera::getVisitingCamera();
    
    Mat4 cameraModelMat = camera->getNodeToWorldTransform();
    Mat4 projectionMat = camera->getProjectionMatrix();
    // Ignore the translation
    cameraModelMat.m[12] = cameraModelMat.m[13] = cameraModelMat.m[14] = 0;
    // prescale the matrix to account for the camera fov
    cameraModelMat.scale(1 / projectionMat.m[0], 1 / projectionMat.m[5], 1.0);
    
    auto state = getGLProgramState();
    state->apply(transform);

    Vec4 color(_displayedColor.r / 255.f, _displayedColor.g / 255.f, _displayedColor.b / 255.f, 1.f);
    state->setUniformVec4("u_color", color);
    state->setUniformMat4("u_cameraRot", cameraModelMat);

    glEnable(GL_DEPTH_TEST);
    RenderState::StateBlock::_defaultState->setDepthTest(true);

    glDepthFunc(GL_LEQUAL);
    RenderState::StateBlock::_defaultState->setDepthFunction(RenderState::DEPTH_LEQUAL);

    glEnable(GL_CULL_FACE);
    RenderState::StateBlock::_defaultState->setCullFace(true);

    glCullFace(GL_BACK);
    RenderState::StateBlock::_defaultState->setCullFaceSide(RenderState::CULL_FACE_SIDE_BACK);
    
    glDisable(GL_BLEND);
    RenderState::StateBlock::_defaultState->setBlend(false);

    if (Configuration::getInstance()->supportsShareableVAO())
    {
        GL::bindVAO(_vao);
    }
    else
    {
        GL::enableVertexAttribs(GL::VERTEX_ATTRIB_FLAG_POSITION);

        glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
        glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 3, GL_FLOAT, GL_FALSE, sizeof(Vec3), nullptr);

        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _indexBuffer);
    }

    glDrawElements(GL_TRIANGLES, (GLsizei)6, GL_UNSIGNED_BYTE, nullptr);

    if (Configuration::getInstance()->supportsShareableVAO())
    {
        GL::bindVAO(0);
    }
    else
    {
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    }

    CC_INCREMENT_GL_DRAWN_BATCHES_AND_VERTICES(1, 4);

    CHECK_GL_ERROR_DEBUG();
}

void Skybox::setTexture(TextureCube* texture)
{
    CCASSERT(texture != nullptr, __FUNCTION__);

    texture->retain();

    if (_texture)
        _texture->release();

    _texture = texture;

    getGLProgramState()->setUniformTexture("u_Env", _texture);
}

void Skybox::reload()
{
    initBuffers();
}

NS_CC_END