cup_edit/thermion_dart/test/projection_tests.dart

@Timeout(const Duration(seconds: 600))
import 'dart:async';
import 'dart:io';
import 'dart:math';
import 'dart:typed_data';
import 'package:test/test.dart';
import 'package:thermion_dart/src/utils/src/texture_projection.dart';
import 'package:thermion_dart/thermion_dart.dart';
import 'helpers.dart';

Future<Texture> createTextureFromImage(TestHelper testHelper) async {
  final image = await FilamentApp.instance!.decodeImage(
      File("${testHelper.testDir}/assets/cube_texture2_512x512.png")
          .readAsBytesSync());
  final texture = await FilamentApp.instance!
      .createTexture(await image.getWidth(), await image.getHeight());
  await texture.setLinearImage(
      image, PixelDataFormat.RGBA, PixelDataType.FLOAT);
  return texture;
}

Future<ThermionAsset> _makeCube(
    TestHelper testHelper, ThermionViewer viewer) async {
  final cube = await testHelper.createCube(viewer);
  var ubershader = await cube.getMaterialInstanceAt();
  await ubershader.setDepthCullingEnabled(true);
  await ubershader.setDepthWriteEnabled(true);
  await ubershader.setCullingMode(CullingMode.BACK);
  await ubershader.setParameterInt("baseColorIndex", 0);

  return cube;
}

void main() async {
  final testHelper = TestHelper("projection");
  await testHelper.setup();

  group('projection', () {
    test('project texture & UV unwrap', () async {
      await testHelper.withViewer((viewer) async {
        final camera = await viewer.getActiveCamera();
        await viewer.view.setFrustumCullingEnabled(false);
        await camera.setLensProjection(near: 0.75, far: 100);
        final vp = await viewer.view.getViewport();
        final (width, height) = (vp.width, vp.height);
        final dist = 5.0;
        await camera.lookAt(
          Vector3(
            -0.5,
            dist,
            dist,
          ),
        );

        final cube = await _makeCube(testHelper, viewer);
        final ubershader = await cube.getMaterialInstanceAt();
        final originalTexture = await createTextureFromImage(testHelper);
        final sampler = await FilamentApp.instance!.createTextureSampler();

        await ubershader.setParameterTexture(
            "baseColorMap", originalTexture, sampler);

        var textureProjection =
            await TextureProjection.create(viewer.view, testHelper.swapChain);

        await FilamentApp.instance!.setClearOptions(0, 0, 0, 1,
            clearStencil: 0, discard: false, clear: true);

        final divisions = 8;
        final projectedImage =
            await FilamentApp.instance!.createImage(width, height, 4);
        final projectedTexture = await FilamentApp.instance!.createTexture(
          width,
          height,
          textureFormat: TextureFormat.RGBA32F,
        );

        var images = <Float32List>[];

        for (int i = 0; i < divisions; i++) {
          await camera.lookAt(
            Vector3(
              sin(i / divisions * pi) * dist,
              dist,
              cos(i / divisions * pi) * dist,
            ),
          );

          await textureProjection.project(cube);
          final depth = textureProjection.getDepthWritePixelBuffer();
          await savePixelBufferToBmp(
              depth, width, height, "${testHelper.outDir.path}/depth_$i.bmp");
          final projected = textureProjection.getProjectedPixelBuffer();
          await savePixelBufferToBmp(projected, width, height,
              "${testHelper.outDir.path}/projected_$i.bmp");
          await cube.setMaterialInstanceAt(ubershader);

          final data = await projectedImage.getData();
          data.setRange(0, data.length, projected.buffer.asFloat32List());

          images.add(projected.buffer.asFloat32List());

          await projectedTexture.setLinearImage(
            projectedImage,
            PixelDataFormat.RGBA,
            PixelDataType.FLOAT,
          );

          await ubershader.setParameterTexture(
            "baseColorMap",
            projectedTexture,
            sampler,
          );

          await testHelper.capture(viewer.view, "capture_uv_retextured_$i");

          await ubershader.setParameterTexture(
              "baseColorMap", originalTexture, sampler);
        }

// Improved blending - treating black pixels as transparent
final blendedImage = Float32List(width * height * 4);
final weightSums = List<double>.filled(width * height, 0.0);

// For each image
for (final image in images) {
  // For each pixel in the image
  for (int p = 0; p < width * height; p++) {
    final baseIdx = p * 4;
    final r = image[baseIdx];
    final g = image[baseIdx + 1];
    final b = image[baseIdx + 2];
    final alpha = image[baseIdx + 3];
    
    // Check if pixel is black (all color channels near zero)
    final isBlack = (r < 0.01 && g < 0.01 && b < 0.01);
    
    // Only include pixels that are non-black AND have non-zero alpha
    if (!isBlack && alpha > 0) {
      // Weight contribution by alpha value
      final weight = alpha;
      blendedImage[baseIdx] += r * weight;
      blendedImage[baseIdx + 1] += g * weight;
      blendedImage[baseIdx + 2] += b * weight;
      blendedImage[baseIdx + 3] += weight;
      
      // Track total weights for normalization
      weightSums[p] += weight;
    }
  }
}

// Normalize by the accumulated weights
for (int p = 0; p < width * height; p++) {
  final baseIdx = p * 4;
  final weightSum = weightSums[p];
  
  if (weightSum > 0) {
    blendedImage[baseIdx] /= weightSum;
    blendedImage[baseIdx + 1] /= weightSum;
    blendedImage[baseIdx + 2] /= weightSum;
    // Set alpha to full for pixels that had contributions
    blendedImage[baseIdx + 3] = 1.0;
  } else {
    // For pixels with no contributions, ensure they're fully transparent
    blendedImage[baseIdx] = 0;
    blendedImage[baseIdx + 1] = 0;
    blendedImage[baseIdx + 2] = 0;
    blendedImage[baseIdx + 3] = 0;
  }
}
        // Set the blended data to the projectedImage
        final data = await projectedImage.getData();
        data.setRange(0, data.length, blendedImage);

        await savePixelBufferToBmp(blendedImage.buffer.asUint8List(), width,
            height, "${testHelper.outDir.path}/blended.bmp",
            hasAlpha: true, isFloat: true);

        // Update the texture with the blended image
        await projectedTexture.setLinearImage(
          projectedImage,
          PixelDataFormat.RGBA,
          PixelDataType.FLOAT,
        );

        // Set the blended texture as the material parameter
        await ubershader.setParameterTexture(
          "baseColorMap",
          projectedTexture,
          sampler,
        );

        // Capture 120 frames orbiting around the cube
        final orbitFrames = 120;
        for (int frame = 0; frame < orbitFrames; frame++) {
          // Calculate camera position based on frame
          final angle = frame / orbitFrames * 2 * pi;
          await camera.lookAt(
            Vector3(
              sin(angle) * dist,
              dist * 0.8, // Slightly lower height
              cos(angle) * dist,
            ),
          );

          // Capture each frame with a sequential number
          await testHelper.capture(viewer.view,
              "capture_uv_blended_orbit_${frame.toString().padLeft(3, '0')}");
        }
      }, createRenderTarget: true);
    });
  });
}