Question

我尝试用fbo制作android ndk opengl es2。但是得到了黑屏。以下是代码。

init fbo

glGenFramebuffers(1, &FBO);
glGenRenderbuffers(1, &RBO);
glGenTextures(1, &FTextureID);

glBindFramebuffer(GL_FRAMEBUFFER, FBO);
glBindRenderbuffer(GL_RENDERBUFFER, RBO);

glRenderbufferStorage(GL_RENDERBUFFER, GL_RGB, m_width, m_height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, RBO);


glBindTexture(GL_TEXTURE_2D, FTextureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
glGenerateMipmap(FTextureID);

glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, FTextureID, 0);
glBindTexture(GL_TEXTURE_2D, 0);

if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
    std::cout << "ERROR::POSTPROCESSOR: Failed to initialize FBO" << std::endl;

glBindRenderbuffer(GL_RENDERBUFFER, 0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);

init_render_data();

m_post_processor_shader.set_int("scene", 0, GL_TRUE);

init_render_data

    GLuint VBO;
GLfloat vertices[] = {
    // Pos        // Tex
    -1.0f, -1.0f, 0.0f, 0.0f,
     1.0f,  1.0f, 1.0f, 1.0f,
    -1.0f,  1.0f, 0.0f, 1.0f,

    -1.0f, -1.0f, 0.0f, 0.0f,
     1.0f, -1.0f, 1.0f, 0.0f,
     1.0f,  1.0f, 1.0f, 1.0f
};

m_vertex_handle = glGetAttribLocation(m_post_processor_shader.get_id(), "vertex");
__android_log_print(ANDROID_LOG_INFO, "[Breakout][post_processor]", "glGetAttribLocation(\"vertex\") = %d\n",
                    m_vertex_handle);

glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);


glEnableVertexAttribArray(m_vertex_handle);
glVertexAttribPointer(m_vertex_handle, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid*)0);
glBindBuffer(GL_ARRAY_BUFFER, 0);

类着色器。 set_int和使用功能

shader& shader::use()
{
    glUseProgram(m_id);
    return *this;
}

void shader::set_int(const GLchar* name, GLuint value, GLboolean use_shader)
{
    if(use_shader)
        use();

    glUniform1f(glGetUniformLocation(m_id, name), value);
}

着色器

顶点

attribute vec4 vertex;

varying vec2 TexCoords;
void main()
{
    gl_Position = vec4(vertex.xy, 0.0f, 1.0f);
    TexCoords = vertex.zw;
}

片段

precision mediump float;

varying vec2 TexCoords;
uniform sampler2D scene;

void main()
{ 
     gl_FragColor = texture2D(scene, TexCoords);
}

渲染

glBindFramebuffer(GL_FRAMEBUFFER, FBO);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

//render scene

glBindFramebuffer(GL_FRAMEBUFFER, 0);
glBindTexture(GL_TEXTURE_2D, 0);

//render texture from fbo
m_post_processor_shader.use();

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, FTextureID);

glBindBuffer(GL_ARRAY_BUFFER, m_VBO);
glEnableVertexAttribArray(m_vertex_handle);
glVertexAttribPointer(m_vertex_handle, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid*)0);

glDrawArrays(GL_TRIANGLES, 0, 6);
glBindBuffer(GL_ARRAY_BUFFER, 0);

着色器编译和链接正确。 fbo创建正确的

glCheckFramebufferStatus(GL_FRAMEBUFFER)返回GL_FRAMEBUFFER_COMPLETE。

场景绘制正确（无fbo）。与fbo黑屏。我能问什么问题吗？

Answer 1

我发现了错误。顶点缓冲区对象的init_render_data变量名称中的值为VBO

GLuint VBO; 
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);

在渲染函数中，我使用变量m_VBO

glBindBuffer(GL_ARRAY_BUFFER, m_VBO);

还有这整个错误

android opengl es2与fbo的渲染得到了黑ck screnn

1 个答案: