//
//  GLCameraBlurFilter.cpp
//  OpenSpades
//
//  Created by yvt on 7/22/13.
//  Copyright (c) 2013 yvt.jp. All rights reserved.
//



#include "GLCameraBlurFilter.h"
#include "IGLDevice.h"
#include "../Core/Math.h"
#include <vector>
#include "GLQuadRenderer.h"
#include "GLProgram.h"
#include "GLProgramAttribute.h"
#include "GLProgramUniform.h"
#include "GLRenderer.h"
#include "../Core/Debug.h"

namespace spades {
	namespace draw {
		GLCameraBlurFilter::GLCameraBlurFilter(GLRenderer *renderer):
		renderer(renderer){
			prevMatrix = Matrix4::Identity();
		}
		
#define M(r,c) (d.m[(r)+(c)*4])
		
		static Matrix4 ReverseMatrix(Matrix4 d){
			return Matrix4(M(1,2)*M(2,1)-M(1,1)*M(2,2),
						   M(1,0)*M(2,2)-M(1,2)*M(2,0),
						   M(1,1)*M(2,0)-M(1,0)*M(2,1),
						   0,
						   M(0,1)*M(2,2)-M(0,2)*M(2,1),
						   M(0,2)*M(2,0)-M(0,0)*M(2,2),
						   M(0,0)*M(2,1)-M(0,1)*M(2,0),
						   0,
						   0, 0, 0, 0,
						   M(0,2)*M(1,1)-M(0,1)*M(1,2),
						   M(0,0)*M(1,2)-M(0,2)*M(1,0),
						   M(0,1)*M(1,0)-M(0,0)*M(1,1),
						   1);
		}
		
		static float MyACos(float v){
			if(v >= 1.f)
				return 0.f;
			else
				return acosf(v);
		}
		
		GLColorBuffer GLCameraBlurFilter::Filter(GLColorBuffer input) {
			SPADES_MARK_FUNCTION();
			
			
			IGLDevice *dev = renderer->GetGLDevice();
			GLQuadRenderer qr(dev);
			
			dev->Enable(IGLDevice::Blend, false);
			
			GLProgram *program = renderer->RegisterProgram("Shaders/PostFilters/CameraBlur.program");
			static GLProgramAttribute programPosition("positionAttribute");
			static GLProgramUniform programTexture("texture");
			static GLProgramUniform programDepthTexture("depthTexture");
			static GLProgramUniform programReverseMatrix("reverseMatrix");
			static GLProgramUniform programShutterTimeScale("shutterTimeScale");
			
			programPosition(program);
			programTexture(program);
			programDepthTexture(program);
			programReverseMatrix(program);
			programShutterTimeScale(program);
			
			const client::SceneDefinition& def = renderer->GetSceneDef();
			Matrix4 newMatrix = Matrix4::Identity();
			newMatrix.m[0] = def.viewAxis[0].x;
			newMatrix.m[1] = def.viewAxis[1].x;
			newMatrix.m[2] = def.viewAxis[2].x;
			newMatrix.m[4] = def.viewAxis[0].y;
			newMatrix.m[5] = def.viewAxis[1].y;
			newMatrix.m[6] = def.viewAxis[2].y;
			newMatrix.m[8] = def.viewAxis[0].z;
			newMatrix.m[9] = def.viewAxis[1].z;
			newMatrix.m[10] = def.viewAxis[2].z;
			
			// othrogonal matrix can be reversed fast
			Matrix4 inverseNewMatrix = newMatrix.Transposed();
			Matrix4 diffMatrix = prevMatrix * inverseNewMatrix;
			prevMatrix = newMatrix;
			Matrix4 reverseMatrix = ReverseMatrix(diffMatrix);
			
			if(diffMatrix.m[0] < .3f ||
			   diffMatrix.m[5] < .3f ||
			   diffMatrix.m[10] < .3f){
				// too much change, skip camera blur
				return input;
			}
			
			float movePixels = MyACos(diffMatrix.m[0]);
			movePixels = std::max(movePixels, MyACos(diffMatrix.m[5]));
			movePixels = std::max(movePixels, MyACos(diffMatrix.m[10]));
			movePixels = tanf(movePixels) / tanf(def.fovX * .5f);
			movePixels *= (float)dev->ScreenWidth() * .5f;
			movePixels *= .3f;
			if(movePixels < 1.f){
				// too less change, skip camera blur
				return input;
			}
			
			movePixels /= 3.f;
			int levels = (int)ceilf(logf(movePixels) / logf(5.f));
			if(levels <= 0)
				levels = 1;
			float shutterTimeScale = .3f;
			
			program->Use();
			
			programTexture.SetValue(0);
			programDepthTexture.SetValue(1);
			programReverseMatrix.SetValue(reverseMatrix);
			
			// composite to the final image
			GLColorBuffer buf = input;
			
			qr.SetCoordAttributeIndex(programPosition());
			dev->ActiveTexture(1);
			dev->BindTexture(IGLDevice::Texture2D, renderer->GetFramebufferManager()->GetDepthTexture());
			dev->ActiveTexture(0);
			
			for(int i = 0; i < levels; i++){
				GLColorBuffer output = input.GetManager()->CreateBufferHandle();
				programShutterTimeScale.SetValue(shutterTimeScale);
				dev->BindTexture(IGLDevice::Texture2D, buf.GetTexture());
				dev->BindFramebuffer(IGLDevice::Framebuffer, output.GetFramebuffer());
				dev->Viewport(0, 0, output.GetWidth(), output.GetHeight());
				qr.Draw();
				dev->BindTexture(IGLDevice::Texture2D, 0);
				shutterTimeScale /= 5.f;
				buf = output;
			}
			
			dev->ActiveTexture(1);
			dev->BindTexture(IGLDevice::Texture2D, 0);
			dev->ActiveTexture(0);
			
			
			return buf;
		}
	}
}