104 lines
2.7 KiB
GLSL
104 lines
2.7 KiB
GLSL
#version 430
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layout (location = 1) uniform vec4 t;
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layout(local_size_x = 1, local_size_y = 1) in; // size of local work group - 1 pixel
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layout(rgba32f, binding = 0) uniform image2D img_output; // rgba32f defines internal format, image2d for random write to output texture
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const float INF = 1000000.0f;
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#include sphere.glsl
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struct Ray
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{
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vec3 origin;
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vec3 direction;
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};
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struct RayHit
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{
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vec3 position;
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float distance;
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vec3 normal;
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};
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void intersectSphere(Ray ray, inout RayHit bestHit, Sphere sphere)
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{
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vec3 d = ray.origin-sphere.center;
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float p1 = -dot(ray.direction,d);
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float p2sqr = p1*p1-dot(d,d)+sphere.radius*sphere.radius;
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if (p2sqr < 0) return;
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float p2 = sqrt(p2sqr);
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float t = p1-p2 > 0 ? p1-p2 : p1+p2;
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if (t > 0 && t < bestHit.distance)
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{
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bestHit.distance = t;
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bestHit.position = ray.origin + t*ray.direction;
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bestHit.normal = normalize(bestHit.position-sphere.center);
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}
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}
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Ray createCameraRay(vec2 uv)
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{
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// transform -1..1 -> 0..1
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//uv = uv*0.5+0.5;
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//uv.x=1-uv.x;
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// transform camera origin to world space
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// TODO: c2w matrix!! for now we just assume the camera is at the origin
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// float3 origin = mul(_CameraToWorld, float4(0.0,0.0,0.0,1.0)).xyz;
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// TODO: offset from centre of the lens for depth of field
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// float2 rd = _CameraLensRadius * randomInUnitDisk();
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// float3 offset = _CameraU * rd.x + _CameraV * rd.y;
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// ...
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float max_x = 5.0;
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float max_y = 5.0;
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Ray ray;
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ray.origin = vec3(uv.x * max_x, uv.y * max_y, 0.0);
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ray.direction = vec3(0.0,0.0,1.0); // ortho forwards
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return ray;
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}
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void main()
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{
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// base pixel colour for the image
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vec4 pixel = vec4(0.0, 0.0, 0.0, 1.0);
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// get index in global work group ie xy position
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ivec2 pixel_coords = ivec2(gl_GlobalInvocationID.xy);
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// set up ray based on pixel position, project it forward with an orthographic projection
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ivec2 dims = imageSize(img_output); // fetch image dimensions
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vec2 uv;
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uv.x = (float(pixel_coords.x * 2 - dims.x) / dims.x) * dims.x/dims.y; // account for aspect ratio
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uv.y = (float(pixel_coords.y * 2 - dims.y) / dims.y);
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Ray ray = createCameraRay(uv);
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RayHit hit;
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hit.position = vec3(0.0,0.0,0.0);
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hit.distance = INF;
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hit.normal = vec3(0.0,0.0,0.0);
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Sphere sphere;
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sphere.center = vec3(0.0,0.0,10.0);
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sphere.radius = 3.0+t.y;
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// ray-sphere intersection
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intersectSphere(ray, hit, sphere);
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if (hit.distance < INF)
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{
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pixel = vec4(t.y,1.0-t.y,1.0,1.0);
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}
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// output to a specific pixel in the image
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imageStore(img_output, pixel_coords, pixel);
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}
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