////  GLBackendTexture.cpp//  libraries/gpu/src/gpu////  Created by Sam Gateau on 1/19/2015.//  Copyright 2014 High Fidelity, Inc.////  Distributed under the Apache License, Version 2.0.//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html//#include "GLBackend.h"#include "GLTexture.h" using namespace gpu;using namespace gpu::gl;  GLuint GLBackend::getTextureID(const TexturePointer& texture) {    GLTexture* object = syncGPUObject(texture);     if (!object) {        return 0;    }     return object->_id;} GLTexture* GLBackend::syncGPUObject(const TexturePointer& texturePointer) {    const Texture& texture = *texturePointer;    // Special case external textures    if (TextureUsageType::EXTERNAL == texture.getUsageType()) {        Texture::ExternalUpdates updates = texture.getUpdates();        if (!updates.empty()) {            Texture::ExternalRecycler recycler = texture.getExternalRecycler();            Q_ASSERT(recycler);            // Discard any superfluous updates            while (updates.size() > 1) {                const auto& update = updates.front();                // Superfluous updates will never have been read, but we want to ensure the previous                 // writes to them are complete before they're written again, so return them with the                 // same fences they arrived with.  This can happen on any thread because no GL context                 // work is involved                recycler(update.first, update.second);                updates.pop_front();            }             // The last texture remaining is the one we'll use to create the GLTexture            const auto& update = updates.front();            // Check for a fence, and if it exists, inject a wait into the command stream, then destroy the fence            if (update.second) {                GLsync fence = static_cast<GLsync>(update.second);                glWaitSync(fence, 0, GL_TIMEOUT_IGNORED);                glDeleteSync(fence);            }             // Create the new texture object (replaces any previous texture object)            new GLExternalTexture(shared_from_this(), texture, update.first);        }         // Return the texture object (if any) associated with the texture, without extensive logic        // (external textures are         return Backend::getGPUObject<GLTexture>(texture);    }     return nullptr;} void GLBackend::do_generateTextureMips(const Batch& batch, size_t paramOffset) {    const auto& resourceTexture = batch._textures.get(batch._params[paramOffset + 0]._uint);    if (!resourceTexture) {        return;    }     // DO not transfer the texture, this call is expected for rendering texture    GLTexture* object = syncGPUObject(resourceTexture);    if (!object) {        return;    }     object->generateMips();} void GLBackend::do_generateTextureMipsWithPipeline(const Batch& batch, size_t paramOffset) {    TexturePointer resourceTexture = batch._textures.get(batch._params[paramOffset + 0]._uint);    if (!resourceTexture) {        return;    }     // Always make sure the GLObject is in sync    GLTexture* object = syncGPUObject(resourceTexture);    if (object) {        GLuint to = object->_texture;        glActiveTexture(GL_TEXTURE0 + gpu::slot::texture::MipCreationInput);        glBindTexture(object->_target, to);        (void)CHECK_GL_ERROR();    } else {        return;    }     auto numMips = batch._params[paramOffset + 1]._int;    if (numMips < 0) {        numMips = resourceTexture->getNumMips();    } else {        numMips = std::min(numMips, (int)resourceTexture->getNumMips());    }     if (_mipGenerationFramebufferId == 0) {        glGenFramebuffers(1, &_mipGenerationFramebufferId);        Q_ASSERT(_mipGenerationFramebufferId > 0);    }     glBindFramebuffer(GL_FRAMEBUFFER, _mipGenerationFramebufferId);    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, 0);     for (int level = 1; level < numMips; level++) {        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, object->_id, level);        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, level - 1);        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, level - 1);         const auto mipDimensions = resourceTexture->evalMipDimensions(level);        glViewport(0, 0, mipDimensions.x, mipDimensions.y);        draw(GL_TRIANGLE_STRIP, 4, 0);    }    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, numMips - 1);    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, 0, 0);    glBindFramebuffer(GL_FRAMEBUFFER, 0);     resetOutputStage();    // Restore viewport    ivec4& vp = _transform._viewport;    glViewport(vp.x, vp.y, vp.z, vp.w);}