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** This file is part of the examples of the Qt Toolkit.
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#include "serverbufferrenderer.h"

#include <QtGui/QOpenGLVertexArrayObject>
#include <QtGui/QOpenGLShaderProgram>

static const GLfloat uv_coords[] = {
    0,0,
    0,1,
    1,0,
    1,1,
};

static const GLfloat vertex_coords[] = {
    -1,-1,0,
    -1,1,0,
    1,-1,0,
    1,1,0,
};

static const char vertex_shader[] =
    "attribute vec3 vertexCoord;"
    "attribute vec2 textureCoord;"
    "uniform mat4 transform;"
    "varying mediump vec2 uv;"
    "void main() {"
    "   uv = textureCoord;"
    "   gl_Position = transform * vec4(vertexCoord,1);"
    "}";

static const char fragment_shader[] =
    "varying mediump vec2 uv;"
    "uniform sampler2D textureSampler;"
    "void main() {"
    "   gl_FragColor = texture2D(textureSampler, uv);"
    "}";

ServerBufferRenderer::ServerBufferRenderer(QWaylandServerBuffer *serverBuffer)
    : QOpenGLFunctions(QOpenGLContext::currentContext())
    , m_server_buffer(serverBuffer)
    , m_texture(0)
    , m_vao(new QOpenGLVertexArrayObject())
    , m_program(new QOpenGLShaderProgram())
    , m_vertexbuffer(0)
    , m_texture_coords(0)

{
    Q_ASSERT(serverBuffer);
    if (serverBuffer->userData()) {
        qWarning("ServerBufferRenderer: Will over QWaylandServerBuffers %p userdata %p", serverBuffer, serverBuffer->userData());
    }
    serverBuffer->setUserData(this);
    m_vao->create();
    m_vao->bind();

    m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, vertex_shader);
    m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, fragment_shader);
    if (!m_program->link()) {
        qDebug() << m_program->log();
    }

    glGenTextures(1,&m_texture);
    glBindTexture(GL_TEXTURE_2D, m_texture);
    serverBuffer->bindTextureToBuffer();

    glGenBuffers(1, &m_vertexbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, m_vertexbuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertex_coords), vertex_coords, GL_STATIC_DRAW);
    m_program->setAttributeBuffer("vertexCoord", GL_FLOAT, 0, 3, 0);

    glGenBuffers(1, &m_texture_coords);
    glBindBuffer(GL_ARRAY_BUFFER, m_texture_coords);
    glBufferData(GL_ARRAY_BUFFER, sizeof(uv_coords), uv_coords, GL_STATIC_DRAW);
    m_program->setAttributeBuffer("textureCoord", GL_FLOAT, 0, 2, 0);

    m_program->enableAttributeArray("vertexCoord");
    m_program->enableAttributeArray("textureCoord");

    m_vao->release();
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

void ServerBufferRenderer::render(const QMatrix4x4 &transform)
{
    m_vao->bind();

    m_program->bind();
    m_program->setUniformValue("transform", transform);

    glBindTexture(GL_TEXTURE_2D, m_texture);

    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

    m_vao->release();
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}