page flip turing

mousePos = event.position-global_position  

and

 material.set_shader_parameter("scale",global_scale)

in script needed, and the COLOR is not correct if using a texture with various ALPHA, need to be improved

Shader code

shader_type canvas_item;
uniform vec2 scale;
uniform vec2 mouse_pos = vec2(-1.,-1.);

vec2 Line2point(vec2 linePoint,vec2 lineDire,vec2 point) {
	lineDire = normalize(lineDire);
	vec2 line2Ori = - linePoint - dot(-linePoint,lineDire)*lineDire;
	vec2 p2Ori = - point - dot(-point,lineDire)*lineDire;
	return line2Ori-p2Ori;
	}
vec4 ColorWithA(vec4 oldCol,vec4 newCol){
	vec4 finalCol;
	if((newCol.a + oldCol.a)>=1.)
	{
		finalCol.rgb = newCol.rgb ;
		finalCol.a =1.0;
	}
	else{
		finalCol.rgb = newCol.a/(newCol.a + oldCol.a)*newCol.rgb + oldCol.a/(newCol.a + oldCol.a)*oldCol.rgb;
		finalCol.a = oldCol.a +newCol.a;
		}
	return 	finalCol;	
	}

void fragment() {
	vec2 uv = UV;
//	vec2 mouse_uv = mouse_pos ;
	
	//拉伸变形校正
	float scale_min = scale.x/scale.y;
	vec2 uv_max = vec2(scale_min,1.);
	float trueScale;
	if(scale.y<scale.x){
		scale_min = scale.y/scale.x;
		uv.y = uv.y * scale_min;
		uv_max = vec2(1.,scale_min);
//		mouse_uv = mouse_pos * TEXTURE_PIXEL_SIZE /scale.x;
		trueScale = scale.x;
		}
	else{
		uv.x = uv.x*scale_min;
//		mouse_uv = mouse_pos * TEXTURE_PIXEL_SIZE /scale.y;
		trueScale = scale.y;
	}
	
	COLOR= texture(TEXTURE,uv);

	
	//鼠标响应
	vec2 pPos = uv / TEXTURE_PIXEL_SIZE * trueScale;
	if (mouse_pos.x>-0.0001)
	{
		vec2 left_bottom = vec2(0.,uv_max.y/TEXTURE_PIXEL_SIZE.y * trueScale);
		vec2 midpoint = (mouse_pos - left_bottom)/2. + left_bottom;
//		vec2 midDirect = vec2(-1.,-1.)/1.414;
		vec2 midDirect = normalize(vec2(-(mouse_pos-left_bottom).y,(mouse_pos-left_bottom).x));
		//bg

		//pageback
		vec2 sharpPoint = vec2(0.,midpoint.y - midDirect.y/midDirect.x * midpoint.x);
		vec2 flipEdgeDire = normalize(sharpPoint - mouse_pos);
		//pagebackBottom
		vec2 sharpPointB = vec2(midpoint.x-midDirect.x/midDirect.y * (midpoint-left_bottom).y,left_bottom.y);
		vec2 flipEdgeDireB = normalize(sharpPointB - mouse_pos);
		
		//圆柱
		float cyOriOff = length(mouse_pos-left_bottom);
		if (cyOriOff>100.) cyOriOff = 100.;//圆柱向里面缩进
		float cyR = cyOriOff*2./PI;
		float pageHDire = PI/6.;
		vec2 midlineToP = Line2point(midpoint,midDirect,pPos);
		vec2 sideEdgeToP = Line2point(mouse_pos,flipEdgeDire,pPos);
		vec2 BottomEdgeToP = Line2point(mouse_pos,flipEdgeDireB,pPos);

		vec2 cyOriToP = midlineToP - normalize(mouse_pos- left_bottom)*cyOriOff;
		vec2 cyEdgeToP = midlineToP - normalize(mouse_pos- left_bottom)*(cyOriOff-cyR);

		bool atBG = (cyOriToP).x<=-0.01;
		bool atPageBack = !atBG&&(sideEdgeToP.y>0.)&&(BottomEdgeToP.x<=0.);
//		bool atCy = (cyOriToP).x<=0.;
		bool atCy = cyEdgeToP.x >=0. && (cyOriToP).x<=0.;
		bool atCyPage = false;
		vec2 uvCy ;
		vec2 uvCyB ;
		
		
		float shadow = 1.;
		if (atCy){
			vec2 cyOri = pPos-cyOriToP;
			vec2 trueDis = cyR*  asin(length(cyOriToP)/cyR)*normalize(cyOriToP);
			vec2 truePos = cyOri+trueDis;
				
			vec2 sideEdgeToTP = Line2point(mouse_pos,flipEdgeDire,truePos);
			vec2 BottomEdgeToTP = Line2point(mouse_pos,flipEdgeDireB,truePos);
			uvCyB = truePos * TEXTURE_PIXEL_SIZE /trueScale;
			shadow *= 1.-pow(length(trueDis)/(cyR*PI/2.),3.);
			
			if ((BottomEdgeToTP.x<0.)&& (sideEdgeToTP.y>0.))
				{
					atCyPage = true;
					uvCy = vec2(length(sideEdgeToTP),left_bottom.y-length(BottomEdgeToTP))*TEXTURE_PIXEL_SIZE /trueScale;
				}
			
			if ((uvCyB.x > uv_max.x)||(uvCyB.y > uv_max.y)||(uvCyB.x <= 0.)|| (uvCyB.y <= 0.))	
				atCy =false;
		}
		
		
		//色彩
		COLOR = vec4(0.);
		//page
		if(!atBG && !atCy){
			vec4 color =  texture(TEXTURE,uv);
			COLOR = ColorWithA(COLOR,color);
		}
//		//cyBottom
		if(atCy)
			{
				vec4 color =  texture(TEXTURE,uvCyB);
//				COLOR.a = 1.;
				COLOR = ColorWithA(COLOR,color);
				COLOR.xyz = COLOR.xyz * shadow;
			}
		if (atCyPage){	
				vec4 color =  texture(TEXTURE,uvCy);
				color.xyz *=0.8;
				COLOR = ColorWithA(COLOR,color);
//				COLOR = color;
				COLOR.xyz = COLOR.xyz*shadow;					
		}
		else if(atPageBack)
			{
				uv = vec2(length(sideEdgeToP),left_bottom.y-length(BottomEdgeToP))*TEXTURE_PIXEL_SIZE /trueScale;
				vec4 color =  texture(TEXTURE,uv);
				color.xyz *=0.8;
				COLOR = ColorWithA(COLOR,color);
			}

		//bg
		vec4 color = COLOR;
		color.xy = uv;
		color.a =1.0;
		COLOR = ColorWithA(color,COLOR);

//		COLOR.xy = (vec2(midLineDis)*.01);
		
		}
	
	// Place fragment code here.

//	FRAGCOORD.xy;
}

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