1 files changed, 155 insertions, 0 deletions
diff --git a/src/datavisualization/engine/shaders/texture3dslice.frag b/src/datavisualization/engine/shaders/texture3dslice.frag
new file mode 100644
index 00000000..c555af98
--- /dev/null
+++ b/src/datavisualization/engine/shaders/texture3dslice.frag
@@ -0,0 +1,155 @@
+#version 120
+
+varying highp vec3 pos;
+varying highp vec3 rayDir;
+
+uniform highp sampler3D textureSampler;
+uniform highp vec3 volumeSliceIndices;
+uniform highp vec4 colorIndex[256];
+uniform highp int color8Bit;
+uniform highp float alphaMultiplier;
+uniform highp int preserveOpacity;
+uniform highp vec3 minBounds;
+uniform highp vec3 maxBounds;
+
+const highp vec3 xPlaneNormal = vec3(1.0, 0, 0);
+const highp vec3 yPlaneNormal = vec3(0, 1.0, 0);
+const highp vec3 zPlaneNormal = vec3(0, 0, 1.0);
+
+void main() {
+    // Find out where ray intersects the slice planes
+    vec3 normRayDir = normalize(rayDir);
+    highp vec3 rayStart = pos;
+    highp float minT = 2.0f;
+    if (normRayDir.x != 0.0 && normRayDir.y != 0.0 && normRayDir.z != 0.0) {
+        highp vec3 boxBounds = vec3(1.0, 1.0, 1.0);
+        highp vec3 invRayDir = 1.0 / normRayDir;
+        if (normRayDir.x < 0)
+            boxBounds.x = -1.0;
+        if (normRayDir.y < 0)
+            boxBounds.y = -1.0;
+        if (normRayDir.z < 0)
+            boxBounds.z = -1.0;
+        highp vec3 t = (boxBounds - rayStart) * invRayDir;
+        minT = min(t.x, min(t.y, t.z));
+    }
+
+    highp vec3 xPoint = vec3(volumeSliceIndices.x, 0, 0);
+    highp vec3 yPoint = vec3(0, volumeSliceIndices.y, 0);
+    highp vec3 zPoint = vec3(0, 0, volumeSliceIndices.z);
+    highp float firstD = minT + 1.0;
+    highp float secondD = firstD;
+    highp float thirdD = firstD;
+    if (volumeSliceIndices.x >= -1.0) {
+        highp float dx = dot(xPoint - rayStart, xPlaneNormal) / dot(normRayDir, xPlaneNormal);
+        if (dx >= 0.0 && dx <= minT)
+            firstD = min(dx, firstD);
+    }
+    if (volumeSliceIndices.y >= -1.0) {
+        highp float dy = dot(yPoint - rayStart, yPlaneNormal) / dot(normRayDir, yPlaneNormal);
+        if (dy >= 0.0 && dy <= minT) {
+            if (dy < firstD) {
+                secondD = firstD;
+                firstD = dy;
+            } else {
+                secondD = dy;
+            }
+        }
+    }
+    if (volumeSliceIndices.z >= -1.0) {
+        highp float dz = dot(zPoint - rayStart, zPlaneNormal) / dot(normRayDir, zPlaneNormal);
+        if (dz >= 0.0) {
+            if (dz < firstD && dz <= minT) {
+                thirdD = secondD;
+                secondD = firstD;
+                firstD = dz;
+            } else if (dz < secondD){
+                thirdD = secondD;
+                secondD = dz;
+            } else {
+                thirdD = dz;
+            }
+        }
+    }
+
+    highp vec4 destColor = vec4(0.0, 0.0, 0.0, 0.0);
+    highp vec4 curColor = vec4(0.0, 0.0, 0.0, 0.0);
+    highp float totalAlpha = 0.0;
+    highp vec3 curRgb = vec3(0, 0, 0);
+    highp float curAlpha = 0.0;
+
+    // Convert intersection to texture coords
+
+    if (firstD <= minT) {
+        highp vec3 texelVec = rayStart + normRayDir * firstD;
+        if (clamp(texelVec.x, minBounds.x, maxBounds.x) == texelVec.x
+                && clamp(texelVec.y, maxBounds.y, minBounds.y) == texelVec.y
+                && clamp(texelVec.z, maxBounds.z, minBounds.z) == texelVec.z) {
+            texelVec = 0.5 * (texelVec + 1.0);
+            curColor = texture3D(textureSampler, texelVec);
+            if (color8Bit != 0)
+                curColor = colorIndex[int(curColor.r * 255.0)];
+
+            if (curColor.a > 0.0) {
+                curAlpha = curColor.a;
+                if (curColor.a == 1.0 && preserveOpacity != 0)
+                    curAlpha = 1.0;
+                else
+                    curAlpha = clamp(curColor.a * alphaMultiplier, 0.0, 1.0);
+                destColor.rgb = curColor.rgb * curAlpha;
+                totalAlpha = curAlpha;
+            }
+        }
+        if (secondD <= minT && totalAlpha < 1.0) {
+            texelVec = rayStart + normRayDir * secondD;
+            if (clamp(texelVec.x, minBounds.x, maxBounds.x) == texelVec.x
+                    && clamp(texelVec.y, maxBounds.y, minBounds.y) == texelVec.y
+                    && clamp(texelVec.z, maxBounds.z, minBounds.z) == texelVec.z) {
+                texelVec = 0.5 * (texelVec + 1.0);
+                curColor = texture3D(textureSampler, texelVec);
+                if (color8Bit != 0)
+                    curColor = colorIndex[int(curColor.r * 255.0)];
+                if (curColor.a > 0.0) {
+                    if (curColor.a == 1.0 && preserveOpacity != 0)
+                        curAlpha = 1.0;
+                    else
+                        curAlpha = clamp(curColor.a * alphaMultiplier, 0.0, 1.0);
+                    curRgb = curColor.rgb * curAlpha * (1.0 - totalAlpha);
+                    destColor.rgb += curRgb;
+                    totalAlpha += curAlpha;
+                }
+            }
+            if (thirdD <= minT && totalAlpha < 1.0) {
+                texelVec = rayStart + normRayDir * thirdD;
+                if (clamp(texelVec.x, minBounds.x, maxBounds.x) == texelVec.x
+                        && clamp(texelVec.y, maxBounds.y, minBounds.y) == texelVec.y
+                        && clamp(texelVec.z, maxBounds.z, minBounds.z) == texelVec.z) {
+                    texelVec = 0.5 * (texelVec + 1.0);
+                    curColor = texture3D(textureSampler, texelVec);
+                    if (curColor.a > 0.0) {
+                        if (color8Bit != 0)
+                            curColor = colorIndex[int(curColor.r * 255.0)];
+                        if (curColor.a == 1.0 && preserveOpacity != 0)
+                            curAlpha = 1.0;
+                        else
+                            curAlpha = clamp(curColor.a * alphaMultiplier, 0.0, 1.0);
+                        curRgb = curColor.rgb * curAlpha * (1.0 - totalAlpha);
+                        destColor.rgb += curRgb;
+                        totalAlpha += curAlpha;
+                    }
+                }
+            }
+        }
+    }
+
+    if (totalAlpha == 0.0)
+        discard;
+
+    // Brighten up the final color if there is some transparency left
+    if (totalAlpha > 0.0 && totalAlpha < 1.0)
+        destColor *= 1.0 / totalAlpha;
+
+    destColor.a = totalAlpha;
+    gl_FragColor = clamp(destColor, 0.0, 1.0);
+}
+