cosmos_sketch.cpp

/*

### cosmos_sketch

To compile, use the command

```bash
clang++ cosmos_sketch.cpp -o cosmos_sketch -std=c++11 -lOpenCL
```

To run, use the command

```bash
./cosmos_sketch <frames> [bodies=24576]
```

This will cause cosmos_sketch to output a bunch of ugly rendered frames to the
directory that it was started in. These rendered frames will be image files,
produced by rendering the corresponding simulation frames generated by running
cosmos_simulate.

## Even more speed

To speed up simulations and renders even more, compile with

```bash
clang++ cosmos_tool.cpp -o cosmos_tool -std=c++11 -lOpenCL -Ofast -march=native
```

*/

#include <iostream>
#include <sstream>
#include <fstream>

#include <ctime>

#include <memory>

// Include stb_image_write.

#define STB_IMAGE_WRITE_IMPLEMENTATION

#include "stb_image_write.h"

// Include OpenCL.

#ifdef __APPLE__

#define CL_SILENCE_DEPRECATION

#include <OpenCL/OpenCL.h>

#else

#include <CL/cl.h>

#endif

// Include the thermal colormap.

#include "thermal_colormap.h"

// Entry point.

int main(int argc, char** argv)
{
	// Parse command line arguments.

	if (argc != 2)
	{
		std::cout << "Usage: " << argv[0] << " <frames> [bodies=24576]" << std::endl;

		return EXIT_FAILURE;
	}

	int frames = atoi(argv[1]);

	int n = 24576;

	if (argc == 3)
	{
		n = atoi(argv[2]);
	}

	// Allocate a buffer to hold the frame body data.

	cl_float4* bodies = (cl_float4*)malloc(n * sizeof(cl_float4));

	// PARAM: The dimensions of the image (which is square).

	int res = 800;

	// Allocate a buffer to hold the rendered frame.

	unsigned char* img = (unsigned char*)malloc(res * res * 3 * sizeof(unsigned char));

	int stride_in_bytes = res * 3;

	// Start the render!

	for (int i = 0; i < frames; i++)
	{
		// Get the starting time.

		clock_t frame_start = clock();

		// Load the current frame.

		std::stringstream name_builder;

		name_builder << "frame_" << i << ".dat";

		std::ifstream frame(name_builder.str());

		frame.read((char*)bodies, n * sizeof(cl_float4));

		frame.close();

		// PARAM: The zoom factor.

		float inv_scale = i / 60.0f;

		// Clear the frame.

		memset(img, 0, res * res * 3 * sizeof(unsigned char));

		// Render the first pass of the bodies.

		for (int i = 0; i < n; i++)
		{
			int x = bodies[i].s[0] / inv_scale + res / 2;
			int y = bodies[i].s[1] / inv_scale + res / 2;

			if (x >= 0 && y >= 0 && x < res && y < res)
			{
				img[y * stride_in_bytes + x * 3] = std::min(255.0f, img[y * stride_in_bytes + x * 3] + 4096 / inv_scale);
			}
		}

		// Render the second pass of the bodies.

		for (int i = 0; i < n; i++)
		{
			int x = bodies[i].s[0] / inv_scale + res / 2;
			int y = bodies[i].s[1] / inv_scale + res / 2;

			if (x >= 0 && y >= 0 && x < res && y < res)
			{
				int value = img[y * stride_in_bytes + x * 3];
				
				img[y * stride_in_bytes + x * 3 + 0] = __thermal_data[value].r * 255;
				img[y * stride_in_bytes + x * 3 + 1] = __thermal_data[value].g * 255;
				img[y * stride_in_bytes + x * 3 + 2] = __thermal_data[value].b * 255;
			}
		}

		// Save the image.

		std::stringstream out_name_builder;

		out_name_builder << "sketch_" << i << ".png";

		stbi_write_png(out_name_builder.str().c_str(), res, res, 3, img, stride_in_bytes);

		// Get the ending time.

		clock_t frame_end = clock();

		// Print the frame elapsed time.

		std::cout << "Frame " << i << " sketched in " << float(frame_end - frame_start) / float(CLOCKS_PER_SEC) << " s" << std::endl;
	}

	return EXIT_SUCCESS;
}