核心代码如下
static const char *vertexShaderSource =
“attribute highp vec2 posAttr;\n”
“varying lowp vec4 col;\n”
“uniform highp mat4 matrix;\n”
“void main() {\n”
" col = vec4(1.0, 0.0, 0.0, 1.0);\n"
" gl_Position = matrix * vec4(posAttr, 0.0, 1.0);\n"
“}\n”;
static const char *fragmentShaderSource =
“varying lowp vec4 col;\n”
“void main() {\n”
" gl_FragColor = col;\n"
“}\n”;
void TriangleWindow::createVertexBuffer()
{
GLfloat vertices] = {
0.0f, 1.0f,
0.0f, 0.0f,
1.0f, 0.0f,
1.0f, 1.0f
};
glGenBuffers(1, &m_vbo);
glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
}
void TriangleWindow::createIndexBuffer()
{
GLfloat indexs] = {
0,1,2
};
glGenBuffers(1, &m_ibo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_ibo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indexs), indexs, GL_STATIC_DRAW);
}
void TriangleWindow::initialize()
{
createVertexBuffer();
createIndexBuffer();
}
glEnableVertexAttribArray(m_posAttr);
glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
glVertexAttribPointer(m_posAttr, 2, GL_FLOAT, GL_FALSE, 0, (const GLvoid*)0);
//glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_ibo);
//glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, 0);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(m_posAttr);
如上代码，程序能看到 三角形，但改成索引绘制时，就显示黑屏了，什么也看不到
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_ibo);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, 0);
//glDrawArrays(GL_TRIANGLES, 0, 3);
使用的是 openGL ES 2.0. 求高手解答？