基于索引绘制glDrawElement

GPU:
vertex shader

uniform mediump mat4 uViewProjMatrix;varying lowp vec4 vColor;void main(void){    gl_Position = uViewProjMatrix * vec4(aPosition.x, aPosition.y, 0.0, 1.0);    vColor = vec4(aPosition.x * 0.5 + 0.5, aPosition.y * 0.5 + 0.5, 0.0, 1.0);}

frag shader

#version 100precision highp float;varying lowp vec4 vColor;void main(void){    gl_FragColor = vColor;}

cpu:
init()

initRendering(void) {    NV_APP_BASE_SHARED_INIT();    NvAssetLoaderAddSearchPath("tutorial/Basic");    mProgram = NvGLSLProgram::createFromFiles("shaders/plain.vert", "shaders/plain.frag");    static const float position[] = {        -1.0f, -1.0f,        1.0f, -1.0f,        -1.0f, 1.0f,        1.0f, 1.0f,    };    //-----------基于索引绘制    static const GLushort plane_indices[] =    {        0, 1, 2, 3    };    glGenBuffers(1, &_index_buffer);    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _index_buffer);    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(plane_indices), plane_indices, GL_STATIC_DRAW);    //--------------    glGenBuffers(1, &_quad_vbo);    glBindBuffer(GL_ARRAY_BUFFER, _quad_vbo);    glBufferData(GL_ARRAY_BUFFER, sizeof(position), NULL, GL_STATIC_DRAW);    glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(position), position);    glGenVertexArrays(1, &_vao);    glBindVertexArray(_vao);    GLint naPosition = mProgram->getAttribLocation("aPosition");    glVertexAttribPointer(naPosition, 2, GL_FLOAT, GL_FALSE, 0, 0);    glEnableVertexAttribArray(0);    glBindVertexArray(0);    glDisableVertexAttribArray(0);}

draw()

draw(void){    CHECK_GL_ERROR();    glClearColor(0.0f, 0.25f, 0.3f, 1.0f);    glClearDepth(1.0f);    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);    CHECK_GL_ERROR();    nv::matrix4f projection_matrix;    nv::perspective(projection_matrix, 3.14f * 0.25f, m_width/(float)m_height, 0.1f, 30.0f);    nv::matrix4f camera_matrix = projection_matrix * m_transformer->getModelViewMat();    CHECK_GL_ERROR();    mProgram->enable();    mProgram->setUniformMatrix4fv("uViewProjMatrix", camera_matrix._array, 1, GL_FALSE);    CHECK_GL_ERROR();    //-----------------------------------------    glBindVertexArray(_vao);    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _index_buffer);    glDrawElements(GL_TRIANGLE_STRIP, 4, GL_UNSIGNED_SHORT,NULL);    glBindVertexArray(0);    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);    //------------------------------------------    CHECK_GL_ERROR();    mProgram->disable();}