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https://github.com/dyuri/repa-shader.git
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45 lines
1.3 KiB
GLSL
45 lines
1.3 KiB
GLSL
#define STEPSIZE .1
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#define DENSCALE .1
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void main() {
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// Compute the pixel's position in view space.
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vec2 fragCoord = gl_FragCoord.xy / resolution.xy;
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vec3 viewPos = vec3((fragCoord * 2.0 - 1.0), 0.5);
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viewPos.y *= -1.0; // Flip Y axis to match WebGL convention.
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vec3 camPos = vec3(.5 + m.x * .5, .5 + m.y * .5, -.25);
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vec3 camDir = vec3(1., 1., 1.);
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// Convert the pixel's position to world space.
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vec3 worldPos = camPos + viewPos * length(camDir);
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// Compute the ray direction in world space.
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vec3 rayDir = normalize(worldPos - camPos);
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// Initialize the color and transparency values.
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vec4 color = vec4(0.0);
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float alpha = 0.0;
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// Perform the ray-marching loop.
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for (float t = 0.0; t < 2.0; t += STEPSIZE) {
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// Compute the position along the ray.
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vec3 pos = camPos + rayDir * t;
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// Sample the density at the current position.
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float density = texture(test3d, pos).x * DENSCALE;
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// Accumulate the color and transparency values.
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vec4 sampleColor = vec4(1.0, 0.5, 0.2, 1.0);
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color += (1.0 - alpha) * sampleColor * density;
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alpha += (1.0 - alpha) * density;
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// Stop marching if the transparency reaches 1.0.
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if (alpha >= 1.0) {
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break;
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}
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}
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// Output the final color and transparency.
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o = vec4(color.rgb, alpha);
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}
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