我已经使用FrameBuffer和Texture实现了一个简单的延迟渲染器。
绘图看起来像这样:
代码(C#):
private void Setup()
{
{
_shader = new Shader();
_shader.AddShader( ShaderType.VertexShader , vertShaderSource );
_shader.AddShader( ShaderType.FragmentShader , fragShaderSource );
_shader.CompileAndLink();
_vertexArray = new VertexArray();
_vertexArray.Bind();
_vertexBuffer = new VertexBuffer();
_vertexBuffer.SetLayout<float>();
_vertexBuffer.Bind();
_vertexBuffer.Update( ObjectData );
_indexBuffer = new IndexBuffer();
_indexBuffer.SetLayout<int>();
_indexBuffer.Bind();
_indexBuffer.Update( ObjectIndices );
GL.VertexAttribPointer( index: 0 , size: 3 , VertexAttribPointerType.Float , normalized: false ,
stride: sizeof( float ) * 3 , offset: 0 );
GL.EnableVertexAttribArray( 0 );
_uniformBuffer = new UniformBuffer();
_uniformBuffer.SetLayout<uUniformBlock>();
_uniformBuffer.Bind();
_uniformBuffer.Reserve( 1 );
_shader.BindUniformBuffer( _uniformBuffer , nameof( uUniformBlock ) , UNIFORM_BLOCK_BINDING_uUniformBlock );
_vertexArray.Unbind();
_vertexBuffer.Unbind();
_uniformBuffer.Unbind();
}
// Quad
{
_frameBuffer = new FrameBuffer();
_frameBuffer.Bind();
_quadTexture = new Texture( TextureTarget.Texture2D , this.Width , this.Height );
_quadTexture.Bind();
GL.GenerateMipmap( GenerateMipmapTarget.Texture2D );
_frameBuffer.Attach( FramebufferAttachment.ColorAttachment0 , _quadTexture );
_frameBuffer.CheckStatus();
_quadShader = new Shader();
_quadShader.AddShader( ShaderType.VertexShader , quadVertShaderSource );
_quadShader.AddShader( ShaderType.FragmentShader , quadFragShaderSource );
_quadShader.CompileAndLink();
_quadVertexArray = new VertexArray();
_quadVertexArray.Bind();
_quadVertexBuffer = new VertexBuffer();
_quadVertexBuffer.SetLayout<float>();
_quadVertexBuffer.Bind();
_quadVertexBuffer.Update( QuadData );
// Pos X Y
GL.VertexAttribPointer( index: 0 , size: 2 , VertexAttribPointerType.Float , normalized: false ,
stride: sizeof( float ) * 4 , offset: sizeof( float ) * 0 );
GL.EnableVertexAttribArray( 0 );
// TexCoord U V
GL.VertexAttribPointer( index: 1 , size: 2 , VertexAttribPointerType.Float , normalized: false ,
stride: sizeof( float ) * 4 , offset: sizeof( float ) * 2 );
GL.EnableVertexAttribArray( 1 );
_quadVertexArray.Unbind();
_quadVertexBuffer.Unbind();
_quadTexture.Unbind();
}
}
private double _totalTime = 0.0;
protected override void OnRenderFrame( FrameEventArgs args )
{
base.OnRenderFrame( args );
GL.Clear( ClearBufferMask.ColorBufferBit );
_totalTime += args.Time;
var color = new Vector3( (float)Math.Sin( _totalTime * 2.0 ) ,
(float)Math.Cos( _totalTime * 3.0 ) ,
(float)Math.Tan( _totalTime * 1.0 ) );
var uniformBlackData = new uUniformBlock() {
uR = color.X ,
uG = color.Y ,
uB = color.Z ,
};
// first pass
{
_frameBuffer.Bind();
GL.Clear( ClearBufferMask.ColorBufferBit );
GL.ClearColor( 0.2f , 0.3f , 0.3f , 1.0f );
_shader.Activate();
// _shader.SetUniform( "uColor" , color );
_vertexArray.Bind();
_uniformBuffer.Bind(); // TODO: is this needed?
_uniformBuffer.Update( uniformBlackData );
GL.DrawElements( PrimitiveType.Triangles , count: ObjectIndices.Length ,
DrawElementsType.UnsignedInt , IntPtr.Zero );
_vertexArray.Unbind();
}
// second pass
{
FrameBuffer.BindDefaultFrameBuffer();
GL.Clear( ClearBufferMask.ColorBufferBit );
GL.ClearColor( 1.0f , 0.0f , 1.0f , 1.0f );
_quadShader.Activate();
GL.ActiveTexture( TextureUnit.Texture0 + 0 );
_quadShader.SetUniform( "uTexture0" , 0 );
_quadVertexArray.Bind();
_quadTexture.Bind();
GL.DrawArrays( PrimitiveType.Triangles , 0 , 6 );
_quadVertexArray.Unbind();
}
base.SwapBuffers();
}
它看起来像这样:
但是,我希望结果是相反的-互换了灰色和洋红色的颜色。
被渲染为具有灰色背景的纹理和第二相四边形纹理是否不应该被洋红色包围(因为其略小于窗口大小)?
这幅图片是正确的还是我的理解不够准确?
答案 0 :(得分:1)
在清除缓冲区之前,您必须设置清除颜色:
GL.Clear( ClearBufferMask.ColorBufferBit );
GL.ClearColor( 0.2f , 0.3f , 0.3f , 1.0f );
GL.ClearColor( 0.2f , 0.3f , 0.3f , 1.0f );
GL.Clear( ClearBufferMask.ColorBufferBit );
GL.ClearColor
指定GL.Clear( ClearBufferMask.ColorBufferBit )
用于填充帧缓冲区中像素的颜色。
请参见OpenGL Wiki页面glClear
:
glClear
将窗口的位平面区域设置为先前由glClearColor
,glClearDepth
和glClearStencil
选择的值。 [...]