slices working; broken orientation

vis/shaders/4d/4d.gm.glsl

@@ -0,0 +1,73 @@
+#version 440 core
+
+layout(points) in;
+layout(triangle_strip, max_vertices=4) out;
+
+layout(std430, binding=1) buffer Positions {
+    vec4 verts[];
+};
+
+layout(std140, binding=1) uniform Matrices {
+    mat4 proj;
+    mat4 view;
+};
+
+in ivec4 vInds[];
+
+out vec4 pos;
+
+out gl_PerVertex {
+    vec4 gl_Position;
+};
+
+float unmix(float u, float v) {
+    return (u) / (u - v);
+}
+
+void emit(vec4 v) {
+    pos = v;
+    gl_Position = proj * vec4(v.xyz, 1);
+    EmitVertex();
+}
+
+void main() {
+    //    vec4 pos4[4];
+    //    for (int i = 0; i < 4; ++i) pos4[i] = view * verts[vInds[0][i]];
+    //
+    //    for (int i = 0; i < 4; ++i) emit(pos4[i]);
+    //    EndPrimitive();
+    //    return;
+
+    vec4 pos4[4];
+    for (int i = 0; i < 4; ++i) pos4[i] = view * verts[vInds[0][i]];
+
+    int lo[4], L = 0;
+    int hi[4], H = 0;
+
+    float x = 0.7;
+
+    for (int i = 0; i < 4; ++i) {
+        if (pos4[i].w+x < 0) {
+            lo[L++] = i;
+        } else {
+            hi[H++] = i;
+        }
+    }
+
+    vec4 sect[4]; int S = 0;
+    for (int l = 0; l < L; ++l)
+    for (int h = H-1; h >=0; --h) {
+        vec4 a = pos4[lo[l]];
+        vec4 b = pos4[hi[h]];
+
+        float t = unmix(a.w+x, b.w+x);
+        sect[S++] = mix(a, b, t);
+        //                sect[S++] = (0.0 - a.w) / (b.w - a.w) * (b - a) + a;
+    }
+
+    for (int s = 0; s < S; ++s) {
+        emit(sect[s]);
+    }
+
+    EndPrimitive();
+}

vis/shaders/4d/4d.vs.glsl

@@ -0,0 +1,27 @@
+#version 440 core
+
+layout(std430, binding=1) buffer Positions {
+    vec4 verts[];
+};
+
+layout(std140, binding=1) uniform Matrices {
+    mat4 proj;
+    mat4 view;
+};
+
+layout(location=0) in ivec4 inds;
+
+out ivec4 vInds;
+
+out gl_PerVertex {
+    vec4 gl_Position;
+    float gl_PointSize;
+};
+
+void main() {
+    vInds = inds;
+
+    vec4 pos = view * verts[vInds.x];
+    gl_Position = proj * vec4(pos.xyz, 1);
+    gl_PointSize = 5;
+}

vis/shaders/one-color.fs.glsl

@@ -2,11 +2,11 @@
 
 layout(location=2) uniform vec3 c;
 
-in vec4 vpos;
+in vec4 pos;
 
 out vec4 color;
 
 void main() {
-    float d = smoothstep(-2, 2, vpos.z);
+    float d = smoothstep(-2, 2, pos.z);
     color = vec4(c * d, 1);
 }