GLSL ray casting shadertoy code.rtf

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{\fonttbl\f0\fswiss\fcharset0 Helvetica;}
{\colortbl;\red255\green255\blue255;}
{\*\expandedcolortbl;;}
\margl1440\margr1440\vieww10800\viewh8400\viewkind0
\pard\tx566\tx1133\tx1700\tx2267\tx2834\tx3401\tx3968\tx4535\tx5102\tx5669\tx6236\tx6803\pardirnatural\partightenfactor0

\f0\fs24 \cf0 const vec4  skyColor  = vec4(1.0, 1.0, 1.0, 1.00);\
const float PI = 3.14159265f;\
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struct Ray\
\{\
    vec3 origin;\
    vec3 direction;\
    vec3 energy;\
\};\
Ray CreateRay(vec3 origin, vec3 direction)\
\{\
    Ray ray;\
    ray.origin = origin;\
    ray.direction = direction;\
    ray.energy = vec3(1.0, 1.0, 1.0);\
    return ray;\
\}\
\
Ray CreateCameraRay(vec2 coord)\
\{\
    vec2 uv = (coord * 2.0 - iResolution.xy) / iResolution.y;\
    vec2 mo = iMouse.xy / iResolution.y * 3.5;\
    if (mo == vec2(0)) mo = vec2(0,1.75);\
    vec3 ro = 5.0 * vec3(sin(mo.x), 2.0-mo.y, cos(mo.x));\
    vec3 z = normalize(ro);\
    vec3 x = normalize(cross(vec3(0.0, 1.0, 0.0), z));\
    vec3 rd = mat3(x, cross(z, x), z) * vec3(uv, -1.0);\
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    return CreateRay(ro, rd);\
\}\
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struct RayHit\
\{\
    vec3 position;\
    float distance;\
    vec3 normal;\
\};\
RayHit CreateRayHit()\
\{\
    RayHit hit;\
    hit.position = vec3(0.0f, 0.0f, 0.0f);\
    hit.distance = 9999.0;\
    hit.normal = vec3(0.0f, 0.0f, 0.0f);\
    return hit;\
\}\
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void IntersectGroundPlane(Ray ray, inout RayHit bestHit, vec3 pn, float pd)\
\{\
    \
    // Calculate distance along the ray where the ground plane is intersected\
    float denominator = dot(ray.direction, pn);\
    float t = -(dot(ray.origin, pn) + pd) / denominator;\
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    if (t > 0.0 && t < bestHit.distance)\
    \{\
    \
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        bestHit.distance = t;\
        bestHit.position = ray.origin + t * ray.direction;\
        bestHit.normal = pn;\
    \}\
\}\
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void IntersectSphere(Ray ray, inout RayHit bestHit, vec4 sphere)\
\{\
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    float t = -1.0;\
    float a = dot(ray.direction, ray.direction);\
    vec3 s0_r0 = ray.origin - sphere.xyz;\
    float b = 2.0 * dot(ray.direction, s0_r0);\
    float c = dot(s0_r0, s0_r0) - (sphere.a * sphere.a);\
    if (!(b*b - 4.0*a*c < 0.0)) \{\
        t = (-b - sqrt((b*b) - 4.0*a*c))/(2.0*a);\
    \}\
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    if (t > 0.0 && t < bestHit.distance)\
    \{\
        bestHit.distance = t;\
        bestHit.position = ray.origin + t * ray.direction;\
        bestHit.normal = normalize(bestHit.position - sphere.xyz);\
    \}\
\}\
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const vec4 groundplane = vec4(0.0,1.0,0.0,5.0);//normal vector.xyz,distance from origin\
//const vec4 groundplane2 = vec4(0.58,0.99,0.0,7.0); //45\'b0 angle\
//const vec4 groundplane2 = vec4(1.0,0.0,0.0,7.0); //90\'b0 angle\
const vec4 sphere1 = vec4(0.0,0.0,0.0,1.0);//position.xyz, radius\
const vec4 sphere2 = vec4(-7.0,-10.0,10.0,8.0);\
const vec4 sphere3 = vec4(5.0,4.0,-10.0,7.0);\
\
RayHit Trace(Ray ray)\
\{\
    RayHit bestHit = CreateRayHit();\
    IntersectGroundPlane(ray, bestHit,groundplane.xyz,groundplane.a);\
    IntersectSphere(ray, bestHit, sphere1);\
    IntersectSphere(ray, bestHit, sphere2);\
    IntersectSphere(ray, bestHit, sphere3);\
    //IntersectGroundPlane(ray, bestHit,groundplane2.xyz,groundplane2.a);\
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    return bestHit;\
\}\
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vec3 Shade(inout Ray ray, RayHit hit)\
\{\
    if (hit.distance < 9900.0)\
    \{\
        vec3 specular = vec3(1.0f, 0.78f, 0.34f);//shinny gold\
        \
        \
        // Reflect the ray and multiply energy with specular reflection\
        ray.origin = hit.position + hit.normal * 0.001f;\
        ray.direction = reflect(ray.direction, hit.normal);\
        ray.energy *= specular;\
        \
        //color\
        return vec3(0.0, 0.0, 0.0);// Return nothing/ silver\
        //return vec3(1.0f, 0.78f, 0.34f);//gold\
        //return vec3(0.0, 0.0, 1.0);// blue\
/*\
        // Return the normal/ rainbow\
        return hit.normal;\
        //return hit.normal * 0.5f + 0.5f;\
*/\
        \
    \}\
    else\
    \{\
        // Erase the ray's energy - the sky doesn't reflect anything\
        ray.energy = vec3(0.12);\
/*\
        //For 2D texture only\
        float theta = acos(ray.direction.y) / -PI;\
        float phi = atan(ray.direction.x, -ray.direction.z) / -PI * 0.5f;\
        return texture(iChannel0, vec2(phi, theta)).xyz;\
*/\
        return texture(iChannel0, ray.direction).xyz;//texture\
        //return ray.direction* 0.5 + 0.5;//uv rainbow\
    \}\
\}\
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void mainImage( out vec4 fragColor, in vec2 fragCoord )\
\{\
    \
    Ray ray = CreateCameraRay(fragCoord);\
    \
    vec3 result = vec3(0.0, 0.0, 0.0);\
    \
    for (int i = 0; i < 8; i++)\
    \{\
        RayHit hit = Trace(ray);\
        result += ray.energy * Shade(ray, hit);\
        if (!any(greaterThan(ray.energy,vec3(0.001)))) break;\
        \
    \}\
    fragColor = vec4(result,1.0);\
   \
/*\
    //flat color no reflection\
    RayHit hit = Trace(ray);\
    vec3 result = Shade(ray, hit);//modify Shade function\
    fragColor = vec4(result,1.0);\
*/    \
    \
    //fragColor = texture(iChannel0, ray.direction);\
    //fragColor = vec4(ray.direction* 0.5f + 0.5f, 1.0f);\
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\}}