98 lines
3.1 KiB
C++
98 lines
3.1 KiB
C++
#include <glog/logging.h>
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#include <GL/gl.h>
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#include "FlatLayerVisualisation.hpp"
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using namespace std;
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using namespace fmri;
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static inline void computeColor(float intensity, float limit, float* destination)
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{
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const float saturation = min(-log(abs(intensity) / limit) / 10.0f, 1.0f);
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if (intensity > 0) {
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destination[0] = saturation;
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destination[1] = saturation;
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destination[2] = 1;
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} else {
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destination[0] = 1;
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destination[1] = saturation;
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destination[2] = saturation;
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}
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}
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FlatLayerVisualisation::FlatLayerVisualisation(const fmri::LayerData &layer) :
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faceCount(layer.numEntries() * 4),
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vertexBuffer(new float[faceCount * 3]),
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colorBuffer(new float[faceCount * 3]),
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indexBuffer(new int[faceCount * 3])
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{
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auto& shape = layer.shape();
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CHECK_EQ(shape.size(), 2) << "layer should be flat!" << endl;
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CHECK_EQ(shape[0], 1) << "Only single images supported." << endl;
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const auto limit = (int) layer.numEntries();
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auto data = layer.data();
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const auto [minElem, maxElem] = minmax_element(data, data + limit);
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auto scalingMax = max(abs(*minElem), abs(*maxElem));
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int v = 0;
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for (int i = 0; i < limit; ++i) {
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setVertexPositions(i, vertexBuffer.get() + 12 * i);
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const int vertexBase = i * 4;
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// Define the colors for the vertices
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for (int c = 0; c < 4; ++c) {
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computeColor(data[i], scalingMax, &colorBuffer[12 * i + 3 * c]);
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}
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// Create the index set for the faces
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// Simply connect all vertices in ascending order and it works.
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indexBuffer[v++] = vertexBase;
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indexBuffer[v++] = vertexBase + 1;
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indexBuffer[v++] = vertexBase + 2;
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indexBuffer[v++] = vertexBase;
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indexBuffer[v++] = vertexBase + 1;
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indexBuffer[v++] = vertexBase + 3;
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indexBuffer[v++] = vertexBase;
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indexBuffer[v++] = vertexBase + 2;
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indexBuffer[v++] = vertexBase + 3;
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indexBuffer[v++] = vertexBase + 1;
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indexBuffer[v++] = vertexBase + 2;
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indexBuffer[v++] = vertexBase + 3;
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}
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assert(v == faceCount * 3);
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}
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void FlatLayerVisualisation::render()
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{
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glEnableClientState(GL_VERTEX_ARRAY);
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glEnableClientState(GL_COLOR_ARRAY);
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glVertexPointer(3, GL_FLOAT, 0, vertexBuffer.get());
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glColorPointer(3, GL_FLOAT, 0, colorBuffer.get());
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glDrawElements(GL_TRIANGLES, faceCount * 3, GL_UNSIGNED_INT, indexBuffer.get());
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glDisableClientState(GL_VERTEX_ARRAY);
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glDisableClientState(GL_COLOR_ARRAY);
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}
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void FlatLayerVisualisation::setVertexPositions(int vertexNo, float *destination)
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{
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int j = 0;
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const float zOffset = -2 * vertexNo;
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// Create the 4 vertices for the pyramid
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destination[j++] = -0.5f;
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destination[j++] = 0;
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destination[j++] = 0.5f + zOffset;
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destination[j++] = 0;
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destination[j++] = 0;
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destination[j++] = -0.5f + zOffset;
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destination[j++] = 0;
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destination[j++] = 1;
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destination[j++] = 0 + zOffset;
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destination[j++] = 0.5;
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destination[j++] = 0;
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destination[j++] = 0.5 + zOffset;
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}
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