commit f6cac1f6ef3f56384b72010cbebf0d850fb43675 Author: Leszek Koltunski Date: Fri Nov 18 17:17:25 2016 +0000 rearrange comments diff --git a/src/main/res/raw/main_vertex_shader.glsl b/src/main/res/raw/main_vertex_shader.glsl index ed65634..0d34baf 100644 --- a/src/main/res/raw/main_vertex_shader.glsl +++ b/src/main/res/raw/main_vertex_shader.glsl @@ -17,32 +17,32 @@ // along with Distorted. If not, see . // ////////////////////////////////////////////////////////////////////////////////////////////// -uniform vec3 u_objD; // half of object width x half of object height X half the depth; - // point (0,0,0) is the center of the object +uniform vec3 u_objD; // half of object width x half of object height X half the depth; + // point (0,0,0) is the center of the object -uniform float u_Depth; // max absolute value of v.z ; beyond that the vertex would be culled by the near or far planes. - // I read OpenGL ES has a built-in uniform variable gl_DepthRange.near = n, - // .far = f, .diff = f-n so maybe u_Depth is redundant - // Update: this struct is only available in fragment shaders +uniform float u_Depth; // max absolute value of v.z ; beyond that the vertex would be culled by the near or far planes. + // I read OpenGL ES has a built-in uniform variable gl_DepthRange.near = n, + // .far = f, .diff = f-n so maybe u_Depth is redundant + // Update: this struct is only available in fragment shaders -uniform mat4 u_MVPMatrix; // A constant representing the combined model/view/projection matrix. -uniform mat4 u_MVMatrix; // A constant representing the combined model/view matrix. +uniform mat4 u_MVPMatrix; // A constant representing the combined model/view/projection matrix. +uniform mat4 u_MVMatrix; // A constant representing the combined model/view matrix. -attribute vec3 a_Position; // Per-vertex position information we will pass in. -attribute vec3 a_Normal; // Per-vertex normal information we will pass in. -attribute vec2 a_TexCoordinate; // Per-vertex texture coordinate information we will pass in. +attribute vec3 a_Position; // Per-vertex position information we will pass in. +attribute vec3 a_Normal; // Per-vertex normal information we will pass in. +attribute vec2 a_TexCoordinate; // Per-vertex texture coordinate information we will pass in. -varying vec3 v_Position; // -varying vec3 v_Normal; // -varying vec2 v_TexCoordinate; // +varying vec3 v_Position; // +varying vec3 v_Normal; // +varying vec2 v_TexCoordinate; // -uniform int vNumEffects; // total number of vertex effects +uniform int vNumEffects; // total number of vertex effects #if NUM_VERTEX>0 -uniform int vType[NUM_VERTEX]; // their types. -uniform vec4 vUniforms[3*NUM_VERTEX]; // i-th effect is 3 consecutive vec4's: [3*i], [3*i+1], [3*i+2]. - // The first vec4 is the Interpolated values, - // next is half cache half Center, the third - the Region. +uniform int vType[NUM_VERTEX]; // their types. +uniform vec4 vUniforms[3*NUM_VERTEX];// i-th effect is 3 consecutive vec4's: [3*i], [3*i+1], [3*i+2]. + // The first vec4 is the Interpolated values, + // next is half cache half Center, the third - the Region. #endif #if NUM_VERTEX>0 @@ -163,38 +163,46 @@ void restrictZ(inout float v) // // Deform the whole shape of the Object by force V // -// If the point of application (Sx,Sy) is on the edge of the Object, then: +// If the point of application (Sx,Sy) is on the upper edge of the Object, then: // a) ignore Vz // b) change shape of the whole Object in the following way: -// Suppose the upper-left corner of the Object rectangle is point L, upper-right - R, force vector V is applied to point M on the upper edge, -// width of the Object = w, height = h, |LM| = Wl, |MR| = Wr, force vector V=(Vx,Vy). Also let H = h/(h+Vy) +// Suppose the upper-left corner of the Object rectangle is point L, upper-right - R, force vector V +// is applied to point M on the upper edge, width of the Object = w, height = h, |LM| = Wl, |MR| = Wr, +// force vector V=(Vx,Vy). Also let H = h/(h+Vy) // // Let now L' and R' be points such that vec(LL') = Wr/w * vec(V) and vec(RR') = Wl/w * vec(V) // now let Vl be a point on the line segment L --> M+vec(V) such that Vl(y) = L'(y) // and let Vr be a point on the line segment R --> M+vec(V) such that Vr(y) = R'(y) // -// Now define points Fl and Fr, the points L and R will be moved to under force V, with Fl(y)=L'(y) and Fr(y)=R'(y) and |VrFr|/|VrR'| = |VlFl|/|VlL'| = H +// Now define points Fl and Fr, the points L and R will be moved to under force V, with Fl(y)=L'(y) +// and Fr(y)=R'(y) and |VrFr|/|VrR'| = |VlFl|/|VlL'| = H // Now notice that |VrR'| = |VlL'| = Wl*Wr / w ( a little geometric puzzle! ) // // Then points L,R under force V move by vectors vec(Fl), vec(Fr) where // vec(Fl) = (Wr/w) * [ (Vx+Wl)-Wl*H, Vy ] = (Wr/w) * [ Wl*Vy / (h+Vy) + Vx, Vy ] // vec(Fr) = (Wl/w) * [ (Vx-Wr)+Wr*H, Vy ] = (Wl/w) * [-Wr*Vy / (h+Vy) + Vx, Vy ] // -// Lets now denote M+vec(V) = M'. The line segment LMR gets distorted to the curve Fl-M'-Fr. Let's now arbitrarilly decide that: +// Lets now denote M+vec(V) = M'. The line segment LMR gets distorted to the curve Fl-M'-Fr. Let's +// now arbitrarilly decide that: // a) at point Fl the curve has to be parallel to line LM' // b) at point M' - to line LR // c) at point Fr - to line M'R // -// Now if Fl=(flx,fly) , M'=(mx,my) , Fr=(frx,fry); direction vector at Fl is (vx,vy) and at M' is (+c,0) where +c is some positive constant, then -// the parametric equations of the Fl--->M' section of the curve (which has to satisfy (X(0),Y(0)) = Fl, (X(1),Y(1))=M', (X'(0),Y'(0)) = (vx,vy), (X'(1),Y'(1)) = (+c,0)) is +// Now if Fl=(flx,fly) , M'=(mx,my) , Fr=(frx,fry); direction vector at Fl is (vx,vy) and at M' +// is (+c,0) where +c is some positive constant, then the parametric equations of the Fl--->M' +// section of the curve (which has to satisfy (X(0),Y(0)) = Fl, (X(1),Y(1))=M', +// (X'(0),Y'(0)) = (vx,vy), (X'(1),Y'(1)) = (+c,0) ) is // // X(t) = ( (mx-flx)-vx )t^2 + vx*t + flx (*) // Y(t) = ( vy - 2(my-fly) )t^3 + ( 3(my-fly) -2vy )t^2 + vy*t + fly // -// Here we have to have X'(1) = 2(mx-flx)-vx which is positive <==> vx<2(mx-flx). We also have to have vy<2(my-fly) so that Y'(t)>0 (this is a must otherwise we have local loops!) -// Similarly for the Fr--->M' part of the curve we have the same equation except for the fact that this time we have to have X'(1)<0 so now we have to have vx>2(mx-flx). +// Here we have to have X'(1) = 2(mx-flx)-vx which is positive <==> vx<2(mx-flx). We also have to +// have vy<2(my-fly) so that Y'(t)>0 (this is a must otherwise we have local loops!) +// Similarly for the Fr--->M' part of the curve we have the same equation except for the fact that +// this time we have to have X'(1)<0 so now we have to have vx>2(mx-flx). // -// If we are stretching the left or right edge of the bitmap then the only difference is that we have to have (X'(1),Y'(1)) = (0,+-c) with + or - c depending on which part of the curve +// If we are stretching the left or right edge of the bitmap then the only difference is that we +// have to have (X'(1),Y'(1)) = (0,+-c) with + or - c depending on which part of the curve // we are tracing. Then the parametric equation is // // X(t) = ( vx - 2(mx-flx) )t^3 + ( 3(mx-flx) -2vx )t^2 + vx*t + flx @@ -202,8 +210,9 @@ void restrictZ(inout float v) // // If we are dragging the top edge: // -// Now point (x,u_objD.x) on the top edge will move by vector (X(t),Y(t)) where those functions are given by (*) and -// t = x < dSx ? (u_objD.x+x)/(u_objD.x+dSx) : (u_objD.x-x)/(u_objD.x-dSx) (this is 'vec2 time' below in the code) +// Now point (x,u_objD.x) on the top edge will move by vector (X(t),Y(t)) where those functions +// are given by (*) and t = x < dSx ? (u_objD.x+x)/(u_objD.x+dSx) : (u_objD.x-x)/(u_objD.x-dSx) +// (this is 'vec2 time' below in the code). // Any point (x,y) will move by vector (a*X(t),a*Y(t)) where a is (y+u_objD.y)/(2*u_objD.y) void deform(in int effect, inout vec4 v)