我在代码中引用了OpenGL Superbible 6。首先,我只想在3D场景中实现对象拾取。最终我决定使用帧缓冲对象并且我成功了,然后我理解了需要解决多边形边缘锯齿问题的问题,因此,我再次重写了代码以利用GL_TEXTURE_2D_MULTISAMPLE
这是帧缓冲的初始化代码无效 window_glview::init_framebuffer()
{
//CREATE FRAMEBUFFER OBJECT
GLenum gl_error=glGetError();
glGenTextures(1,&texture_id_framebuffer_color);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE,texture_id_framebuffer_color);
glTexStorage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE,ANTIALIASING_SAMPLES,GL_RGBA8,client_area.right,client_area.bottom,GL_TRUE);
glGenTextures(1,&texture_id_framebuffer_objectid);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE,texture_id_framebuffer_objectid);
glTexStorage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE,ANTIALIASING_SAMPLES,GL_RGBA8,client_area.right,client_area.bottom,GL_TRUE);
glGenTextures(1,&texture_id_framebuffer_depth);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE,texture_id_framebuffer_depth);
glTexStorage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE,ANTIALIASING_SAMPLES,GL_DEPTH_COMPONENT32,client_area.right,client_area.bottom,GL_TRUE);
gl_error=glGetError();
glGenFramebuffers(1,&buffer_id_framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER,buffer_id_framebuffer);
gl_error=glGetError();
glFramebufferTexture(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,texture_id_framebuffer_color,0);
glFramebufferTexture(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,texture_id_framebuffer_objectid,0);
glFramebufferTexture(GL_FRAMEBUFFER,GL_DEPTH_ATTACHMENT,texture_id_framebuffer_depth,0);
GLenum draw_buffers[] =
{
GL_COLOR_ATTACHMENT0,
GL_COLOR_ATTACHMENT1
};
glDrawBuffers(2,draw_buffers);
GLenum status=glCheckFramebufferStatus(GL_FRAMEBUFFER);
if(status!=GL_FRAMEBUFFER_COMPLETE)
MessageBox(0,L"Failed to create framebuffer object",0,0);
glBindFramebuffer(GL_FRAMEBUFFER,0);
}
对于同一主题的大多数互联网列表来说,这很常见。现在这是我的绘图代码
void window_glview::paint()
{
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
//DRAW TO CUSTOM FRAMEBUFFER
glBindFramebuffer(GL_FRAMEBUFFER,buffer_id_framebuffer);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glLineWidth(1.0);
draw_viewport();
viewport_object_count=0;
draw_lights();
glLineWidth(1.5);
for (unsigned short i=0;i<mesh_count;i++)
{
draw_mesh(mesh_table[i],GL_TRIANGLES,false);
}
//DRAW TO DEFAULT
glBindFramebuffer(GL_FRAMEBUFFER,0);
//USE TEXTURE FROM FRAMEBUFFER COLOR_ATTACHMENT0
glUseProgram(program_id_screen_render);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE,texture_id_framebuffer_color);
//HERE IS A QUAD DRAWING PROCESS
glBindBuffer(GL_ARRAY_BUFFER,buffer_id_screen_quad);
glVertexAttribPointer(0,4,GL_FLOAT,GL_FALSE,24,0);
glEnableVertexAttribArray(0);
glDrawArrays(GL_QUADS,0,4);
SwapBuffers(hDC);
}
顶点着色器很简单
#version 450
layout(location=0) in vec4 _pos;
void main(void)
{
gl_Position=_pos;
}
片段着色器是为了迭代多样本而编写
的#version 450
uniform sampler2DMS screen_texture;
layout(location=0) out vec4 out_color;
void main(void)
{
ivec2 coord=ivec2(gl_FragCoord.xy);
vec4 result=vec4(0.0);
int i;
for (i=0;i<4;i++)
{
result=max(result,texelFetch(screen_texture,coord,i));
}
out_color=result;
}
我最终看到一个黑屏。如果我out_color更改为虱子out_color=vec4(1.0,0.0,0.0,1.0),我会得到红屏。
- 可能出现什么问题?
- 在帧缓冲的初始值设定项函数中,当我将GL_DEPTH_COMPONENT传递给 glTexStorage2DMultisample 时,我得到错误。我决定通过GL_DEPTH_COMPONENT16,它有效。为什么?
- 我是否应该更好地使用RENDERBUFFER进行某些处理,如果是,我如何将其读取为纹理?
渲染到 FBO 时,ID texture_id_framebuffer_color
的纹理(用于最终渲染的纹理)不会附加到 FBO:
glFramebufferTexture(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,texture_id_framebuffer_color,0);
glFramebufferTexture(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,texture_id_framebuffer_objectid,0);
一次只能将一个纹理附着到给定的连接点。因此,当您指定要附加到COLOR_ATTACHMENT0
的第二个纹理时,第一个纹理会自动取消附着。
如果要有两个附件,它们需要使用不同的附件点:
glFramebufferTexture(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,texture_id_framebuffer_color,0);
glFramebufferTexture(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT1,texture_id_framebuffer_objectid,0);