diff options
| author | Mathias Froehlich <Mathias.Froehlich@web.de> | 2011-01-31 07:34:20 +0100 |
|---|---|---|
| committer | Mathias Froehlich <Mathias.Froehlich@web.de> | 2011-01-31 07:34:20 +0100 |
| commit | debc0308161e2a7b6203e84d853933072730c196 (patch) | |
| tree | 0fbf615aa792b4c68693c941fa675bb68f56824e /transmittance.glsl | |
initial
Diffstat (limited to 'transmittance.glsl')
| -rw-r--r-- | transmittance.glsl | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/transmittance.glsl b/transmittance.glsl new file mode 100644 index 0000000..36ca327 --- /dev/null +++ b/transmittance.glsl @@ -0,0 +1,67 @@ +/**
+ * Precomputed Atmospheric Scattering
+ * Copyright (c) 2008 INRIA
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * Author: Eric Bruneton
+ */
+
+// computes transmittance table T using Eq (5)
+
+#ifdef _VERTEX_
+
+void main() {
+ gl_Position = gl_Vertex;
+}
+
+#else
+
+float opticalDepth(float H, float r, float mu) {
+ float result = 0.0;
+ float dx = limit(r, mu) / float(TRANSMITTANCE_INTEGRAL_SAMPLES);
+ float xi = 0.0;
+ float yi = exp(-(r - Rg) / H);
+ for (int i = 1; i <= TRANSMITTANCE_INTEGRAL_SAMPLES; ++i) {
+ float xj = float(i) * dx;
+ float yj = exp(-(sqrt(r * r + xj * xj + 2.0 * xj * r * mu) - Rg) / H);
+ result += (yi + yj) / 2.0 * dx;
+ xi = xj;
+ yi = yj;
+ }
+ return mu < -sqrt(1.0 - (Rg / r) * (Rg / r)) ? 1e9 : result;
+}
+
+void main() {
+ float r, muS;
+ getTransmittanceRMu(r, muS);
+ vec3 depth = betaR * opticalDepth(HR, r, muS) + betaMEx * opticalDepth(HM, r, muS);
+ gl_FragColor = vec4(exp(-depth), 0.0); // Eq (5)
+}
+
+#endif
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