Question

我正在修补Joost van Dongen的 Interior mapping shader，我正试图实现自我遮蔽。我仍然无法弄清楚阴影投射光矢量需要的坐标。你可以看到有点工作的演示at here我附加了光线位置，偏移到相机位置只是为了看看发生了什么但是显然它看起来也不正确。着色器代码如下。在片段着色器中查找SHADOWS DEV。有问题的载体是： shad_E 和 shad_I 。

顶点着色器：

varying vec3 oP; // surface position in object space
varying vec3 oE; // position of the eye in object space
varying vec3 oI; // incident ray direction in object space

varying vec3 shad_E; // shadow light position
varying vec3 shad_I; // shadow direction

uniform vec3 lightPosition;

void main() {

    // inverse veiw matrix
    mat4 modelViewMatrixInverse = InverseMatrix( modelViewMatrix );

    // surface position in object space
    oP = position;

    // position of the eye in object space
    oE = modelViewMatrixInverse[3].xyz;

    // incident ray direction in object space
    oI = oP - oE; 

     // link the light position to camera for testing
     // need to find a way for world space directional light to work
    shad_E = oE - lightPosition;

     // light vector
    shad_I = oP - shad_E;

    gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
}

片段着色器：

varying vec3 oP; // surface position in object space
varying vec3 oE; // position of the eye in object space
varying vec3 oI; // incident ray direction in object space

varying vec3 shad_E; // shadow light position
varying vec3 shad_I; // shadow direction

uniform vec3 wallFreq;

uniform float wallsBias;

uniform vec3 wallCeilingColor;
uniform vec3 wallFloorColor;
uniform vec3 wallXYColor;
uniform vec3 wallZYColor;

float checker(vec2 uv, float checkSize) {
  float fmodResult = mod( floor(checkSize * uv.x) + floor(checkSize * uv.y), 2.0);

  if (fmodResult < 1.0) {
    return 1.0;
  } else {
    return 0.85;
  }
}

void main() {

    // INTERIOR MAPPING by Joost van Dongen
    // http://interiormapping.oogst3d.net/
    // email: joost@ronimo-games.com
    // Twitter: @JoostDevBlog

    vec3 wallFrequencies = wallFreq / 2.0 - wallsBias;

    //calculate wall locations
    vec3 walls = ( floor( oP * wallFrequencies) + step( vec3( 0.0 ), oI )) / wallFrequencies;

    //how much of the ray is needed to get from the oE to each of the walls
    vec3 rayFractions = ( walls - oE) / oI;

    //texture-coordinates of intersections
    vec2 intersectionXY = (oE + rayFractions.z * oI).xy;
    vec2 intersectionXZ = (oE + rayFractions.y * oI).xz;
    vec2 intersectionZY = (oE + rayFractions.x * oI).zy;

    //use the intersection as the texture coordinates for the ceiling
    vec3 ceilingColour = wallCeilingColor * checker( intersectionXZ, 2.0 );
    vec3 floorColour = wallFloorColor * checker( intersectionXZ, 2.0 );
    vec3 verticalColour = mix(floorColour, ceilingColour, step(0.0, oI.y));
    vec3 wallXYColour = wallXYColor * checker( intersectionXY, 2.0 );
    vec3 wallZYColour = wallZYColor * checker( intersectionZY, 2.0 );

    // SHADOWS DEV // SHADOWS DEV // SHADOWS DEV // SHADOWS DEV //

    vec3 shad_P = oP;  // just surface position in object space
    vec3 shad_walls = ( floor( shad_P * wallFrequencies) + step( vec3( 0.0 ), shad_I )) / wallFrequencies;
    vec3 shad_rayFr = ( shad_walls - shad_E ) / shad_I;

    // Cast shadow from ceiling planes (intersectionXZ)

    wallZYColour *= mix( 0.3, 1.0, step( shad_rayFr.x, shad_rayFr.y ));
    verticalColour *= mix( 0.3, 1.0, step( rayFractions.y, shad_rayFr.y ));
    wallXYColour *= mix( 0.3, 1.0, step( shad_rayFr.z, shad_rayFr.y ));

    // SHADOWS DEV // SHADOWS DEV // SHADOWS DEV // SHADOWS DEV //

    // intersect walls
    float xVSz = step(rayFractions.x, rayFractions.z);
    vec3 interiorColour = mix(wallXYColour, wallZYColour, xVSz);
    float rayFraction_xVSz = mix(rayFractions.z, rayFractions.x, xVSz);
    float xzVSy = step(rayFraction_xVSz, rayFractions.y);

    interiorColour = mix(verticalColour, interiorColour, xzVSy);

    gl_FragColor.xyz = interiorColour;  

}

Answer 1

基于我对你想要实现的内容的非常有限的理解，似乎你需要获取眼睛矢量和它所撞击的内部平面之间的交点的位置，然后将其追溯到光线。 / p>

要追溯到光线，您首先必须检查与眼睛矢量相交的内部平面是否从光线的角度向后，这将使其处于阴影中。如果它是朝前的那么你必须从房间内射线投射到灯光并检查与任何其他内部平面的交叉点。

内部映射着色器自阴影

1 个答案: