使用实例化绘图时渲染为纹理
我有几个对象正在绘制，一些使用“常规”方法，一些使用glDrawArraysInstanced ，一切都很好。
我试图通过使用Frame Buffers渲染纹理来添加一些后期处理，但是当我这样做时，如果我绘制实例化对象，我会得到以下结果：
（你可以看到混乱的实际项目）。
如果我评论实例化对象的draw方法，一切都很好。
是否可以使用带渲染的实例化绘图来创建纹理？
一些代码：
实例化对象
void LifeMeter::draw(mat4 wvp)
{
// Set the program to be used in subsequent lines:
glUseProgram(program);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture);
glUniform1i(glGetUniformLocation(program, "texSampler"), /*GL_TEXTURE*/0);
glBindVertexArray(_vao);
glUniformMatrix4fv (glGetUniformLocation(program, "wvp") , 1, GL_FALSE, value_ptr(wvp));
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vec4)*amountOfLives, positions);
glDrawArraysInstanced(GL_TRIANGLE_STRIP, 0, 4, amountOfLives);
// Unbind the Vertex Array object
glBindVertexArray(0);
// Cleanup, not strictly necessary
glUseProgram(0);
}
后处理缓冲区
void PPBuffer::init(int screen_width, int screen_height)
{
// buffer
// The framebuffer, which regroups 0, 1, or more textures, and 0 or 1 depth buffer.
glGenFramebuffers(1, &fbo);
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
/* Texture */
// The texture we're going to render to
glGenTextures(1, &fbo_texture);
// "Bind" the newly created texture : all future texture functions will modify this texture
glBindTexture(GL_TEXTURE_2D, fbo_texture);
glTexImage2D(GL_TEXTURE_2D, 0,GL_RGBA,screen_width, screen_height, 0,GL_RGBA, GL_UNSIGNED_BYTE, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glBindTexture(GL_TEXTURE_2D, 0);
// depth buffer
glGenRenderbuffers(1, &rbo_depth);
glBindRenderbuffer(GL_RENDERBUFFER, rbo_depth);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, screen_width, screen_height );
glBindRenderbuffer(GL_RENDERBUFFER, 0);
/* Framebuffer to link everything together */
glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, fbo_texture, 0); //use more of these for MRT
// glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, fbo_texture1, 0);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rbo_depth);
// Set the list of draw buffers.
GLenum DrawBuffers[1] = {GL_COLOR_ATTACHMENT0};
glDrawBuffers(1,DrawBuffers);
// for MRT: glDrawBuffers(2,{GL_COLOR_ATTACHMENT0,GL_COLOR_ATTACHMENT1});
GLenum status;
if ((status = glCheckFramebufferStatus(GL_FRAMEBUFFER)) != GL_FRAMEBUFFER_COMPLETE) {
fprintf(stderr, "glCheckFramebufferStatus: error %d", status);
exit(0);
}
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// vertices
GLfloat fbo_vertices[] = {
-1, -1,
1, -1,
-1, 1,
1, 1,
};
// Create and bind the object's Vertex Array Object:
glGenVertexArrays(1, &_vao);
glBindVertexArray(_vao);
glGenBuffers(1, &vbo_fbo_vertices);
glBindBuffer(GL_ARRAY_BUFFER, vbo_fbo_vertices);
glBufferData(GL_ARRAY_BUFFER, sizeof(fbo_vertices), fbo_vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
// shader
programManager::sharedInstance()
.createProgram("pp",
SHADERS_DIR "postproc.v.glsl",
SHADERS_DIR "postproc.f.glsl");
program_postproc = programManager::sharedInstance().programWithID("pp");
attribute_v_coord_postproc = glGetAttribLocation(program_postproc, "v_coord");
uniform_fbo_texture = glGetUniformLocation(program_postproc, "fbo_texture");
}
void PPBuffer::setup() {
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
}
void PPBuffer::render() {
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glClearColor(0.3, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glUseProgram(program_postproc);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, fbo_texture);
glUniform1i(uniform_fbo_texture, /*GL_TEXTURE*/0);
glBindVertexArray(_vao);
glEnableVertexAttribArray(attribute_v_coord_postproc);
glBindBuffer(GL_ARRAY_BUFFER, vbo_fbo_vertices);
glVertexAttribPointer(
attribute_v_coord_postproc, // attribute
2, // number of elements per vertex, here (x,y)
GL_FLOAT, // the type of each element
GL_FALSE, // take our values as-is
0, // no extra data between each position
0 // offset of first element
);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glDisableVertexAttribArray(attribute_v_coord_postproc);
glBindBuffer(GL_ARRAY_BUFFER,0);
glBindVertexArray(0);
glUseProgram(0);
}
显示功能
void display(void)
{
_ppbuffer.setup();
// Clear the screen buffer
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
glEnable(GL_DEPTH_TEST);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_TEXTURE_2D);
// tell the model to draw itself...
shuttle->draw(); // Regular object
lifeMeter->draw(Projection ); // Instanced object
_ppbuffer.render();
// Swap those buffers so someone will actually see the results... //
glutSwapBuffers();
}
我解决了这个问题，所以如果有人绊倒这个问题，问题就在于blending功能。
删除线
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
解决了这个问题。 因为我可以没有他们生活，我很满意。
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