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Complete Cook-Torrance BRDF Implementation with Quality-of-Life Improvements #9

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Merged
nurusanwe merged 1 commit into from
Aug 26, 2025
Merged

Complete Cook-Torrance BRDF Implementation with Quality-of-Life Improvements #9

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450 changes: 450 additions & 0 deletions docs/stories/3.1.pure-cook-torrance-brdf-implementation.md
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56 changes: 0 additions & 56 deletions simple_test.cpp
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62 changes: 42 additions & 20 deletions src/core/point_light.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21,24 +21,32 @@ struct PointLight {
// Calculate direction vector from surface point to light source
// Geometric interpretation: normalized vector pointing from surface toward light
// Usage: needed for BRDF evaluation and n·l calculations
Vector3 sample_direction(const Point3& surface_point) const {
std::cout << "\n=== Point Light Direction Calculation ===" << std::endl;
std::cout << "Light position: (" << position.x << ", " << position.y << ", " << position.z << ")" << std::endl;
std::cout << "Surface point: (" << surface_point.x << ", " << surface_point.y << ", " << surface_point.z << ")" << std::endl;
Vector3 sample_direction(const Point3& surface_point, bool verbose = true) const {
if (verbose) {
std::cout << "\n=== Point Light Direction Calculation ===" << std::endl;
std::cout << "Light position: (" << position.x << ", " << position.y << ", " << position.z << ")" << std::endl;
std::cout << "Surface point: (" << surface_point.x << ", " << surface_point.y << ", " << surface_point.z << ")" << std::endl;
}

// Calculate displacement vector from surface to light
Vector3 displacement = position - surface_point;
std::cout << "Displacement vector: (" << displacement.x << ", " << displacement.y << ", " << displacement.z << ")" << std::endl;
if (verbose) {
std::cout << "Displacement vector: (" << displacement.x << ", " << displacement.y << ", " << displacement.z << ")" << std::endl;
}

// Calculate distance for verification
float distance = displacement.length();
std::cout << "Distance to light: " << distance << std::endl;
if (verbose) {
std::cout << "Distance to light: " << distance << std::endl;
}

// Normalize to get unit direction vector
Vector3 direction = displacement.normalize();
std::cout << "Normalized direction: (" << direction.x << ", " << direction.y << ", " << direction.z << ")" << std::endl;
std::cout << "Direction length verification: " << direction.length() << " (should be ≈ 1.0)" << std::endl;
std::cout << "=== Direction calculation complete ===" << std::endl;
if (verbose) {
std::cout << "Normalized direction: (" << direction.x << ", " << direction.y << ", " << direction.z << ")" << std::endl;
std::cout << "Direction length verification: " << direction.length() << " (should be ≈ 1.0)" << std::endl;
std::cout << "=== Direction calculation complete ===" << std::endl;
}

return direction;
}
Expand All @@ -47,39 +55,53 @@ struct PointLight {
// Physical law: inverse square law - irradiance ∝ 1/distance²
// Mathematical formula: E = (I * color) / (4π * distance²)
// Result: incident radiance for use in rendering equation
Vector3 calculate_irradiance(const Point3& surface_point) const {
std::cout << "\n=== Point Light Irradiance Calculation ===" << std::endl;
std::cout << "Light intensity: " << intensity << std::endl;
std::cout << "Light color: (" << color.x << ", " << color.y << ", " << color.z << ")" << std::endl;
Vector3 calculate_irradiance(const Point3& surface_point, bool verbose = true) const {
if (verbose) {
std::cout << "\n=== Point Light Irradiance Calculation ===" << std::endl;
std::cout << "Light intensity: " << intensity << std::endl;
std::cout << "Light color: (" << color.x << ", " << color.y << ", " << color.z << ")" << std::endl;
}

// Calculate distance from light to surface point
Vector3 displacement = position - surface_point;
float distance = displacement.length();
std::cout << "Distance to surface: " << distance << std::endl;
if (verbose) {
std::cout << "Distance to surface: " << distance << std::endl;
}

// Handle degenerate case: light at surface point
if (distance < 1e-6f) {
std::cout << "WARNING: Light and surface point are coincident - returning zero irradiance" << std::endl;
if (verbose) {
std::cout << "WARNING: Light and surface point are coincident - returning zero irradiance" << std::endl;
}
return Vector3(0, 0, 0);
}

// Apply inverse square law: irradiance ∝ 1/distance²
// Factor of 4π comes from solid angle of complete sphere
float distance_squared = distance * distance;
float falloff_factor = 1.0f / (4.0f * M_PI * distance_squared);
std::cout << "Distance squared: " << distance_squared << std::endl;
std::cout << "Falloff factor (1/4πd²): " << falloff_factor << std::endl;
if (verbose) {
std::cout << "Distance squared: " << distance_squared << std::endl;
std::cout << "Falloff factor (1/4πd²): " << falloff_factor << std::endl;
}

// Calculate final irradiance: intensity * color * falloff
Vector3 irradiance = color * (intensity * falloff_factor);
std::cout << "Final irradiance: (" << irradiance.x << ", " << irradiance.y << ", " << irradiance.z << ")" << std::endl;
if (verbose) {
std::cout << "Final irradiance: (" << irradiance.x << ", " << irradiance.y << ", " << irradiance.z << ")" << std::endl;
}

// Verify irradiance is non-negative
if (irradiance.x < 0 || irradiance.y < 0 || irradiance.z < 0) {
std::cout << "WARNING: Negative irradiance detected - this violates physical laws" << std::endl;
if (verbose) {
std::cout << "WARNING: Negative irradiance detected - this violates physical laws" << std::endl;
}
}

std::cout << "=== Irradiance calculation complete ===" << std::endl;
if (verbose) {
std::cout << "=== Irradiance calculation complete ===" << std::endl;
}
return irradiance;
}

Expand Down
35 changes: 27 additions & 8 deletions src/core/progress_reporter.hpp
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Expand Up @@ -36,6 +36,7 @@ class ProgressReporter {
std::chrono::steady_clock::time_point start_time;
std::chrono::steady_clock::time_point last_update_time;
PerformanceTimer* timer;
bool quiet_mode;

// Progress reporting configuration
int reporting_granularity_percent = 5; // Report every 5%
Expand All @@ -51,18 +52,25 @@ class ProgressReporter {
size_t current_memory_usage = 0;

public:
ProgressReporter(int total_pixels, PerformanceTimer* performance_timer)
ProgressReporter(int total_pixels, PerformanceTimer* performance_timer, bool quiet_mode = false)
: total_pixels(total_pixels), completed_pixels(0), last_reported_percentage(-1),
timer(performance_timer) {
timer(performance_timer), quiet_mode(quiet_mode) {
start_time = std::chrono::steady_clock::now();
last_update_time = start_time;

std::cout << "\n=== Progress Reporting Initialized ===" << std::endl;
std::cout << "Total pixels to render: " << total_pixels << std::endl;
std::cout << "Progress reporting granularity: every " << reporting_granularity_percent << "%" << std::endl;
std::cout << "Minimum reporting interval: " << minimum_reporting_interval_seconds << " seconds" << std::endl;
std::cout << "Educational insights: Performance scaling and ETA calculation enabled" << std::endl;
std::cout << "=== Begin Rendering Progress ===" << std::endl;
// Adjust reporting granularity for quiet mode
if (quiet_mode) {
reporting_granularity_percent = 10; // Report every 10% in quiet mode
}

if (!quiet_mode) {
std::cout << "\n=== Progress Reporting Initialized ===" << std::endl;
std::cout << "Total pixels to render: " << total_pixels << std::endl;
std::cout << "Progress reporting granularity: every " << reporting_granularity_percent << "%" << std::endl;
std::cout << "Minimum reporting interval: " << minimum_reporting_interval_seconds << " seconds" << std::endl;
std::cout << "Educational insights: Performance scaling and ETA calculation enabled" << std::endl;
std::cout << "=== Begin Rendering Progress ===" << std::endl;
}
}

// Update progress with completed pixel count and optional memory usage
Expand Down Expand Up @@ -94,6 +102,17 @@ class ProgressReporter {

// Print detailed progress update with educational insights
void print_progress_update(float progress_percentage, float elapsed_seconds) const {
if (quiet_mode) {
// Simple progress display for quiet mode
std::cout << "Progress: " << static_cast<int>(progress_percentage) << "%";
if (completed_pixels == total_pixels) {
std::cout << " - Complete!" << std::endl;
} else {
std::cout << std::endl;
}
return;
}

std::cout << "\n--- Rendering Progress Update ---" << std::endl;
std::cout << std::fixed << std::setprecision(1);
std::cout << "Progress: " << progress_percentage << "% ("
Expand Down
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