C4FoWAmbient.cpp

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/*
 * OpenClonk, http://www.openclonk.org
 *
 * Copyright (c) 2014-2016, The OpenClonk Team and contributors
 *
 * Distributed under the terms of the ISC license; see accompanying file
 * "COPYING" for details.
 *
 * "Clonk" is a registered trademark of Matthes Bender, used with permission.
 * See accompanying file "TRADEMARK" for details.
 *
 * To redistribute this file separately, substitute the full license texts
 * for the above references.
 */
 
#include "C4Include.h"
#include "C4ForbidLibraryCompilation.h"
#include "landscape/fow/C4FoWAmbient.h"
#include "landscape/fow/C4FoW.h"
#include "graphics/C4Draw.h"
 
namespace
{
 
template<typename LightMap>
double AmbientForPix(int x0, int y0, double R, const LightMap& light_map)
{
    double d = 0.;
 
    const int Ri = static_cast<int>(R);
    for(int y = 1; y <= Ri; ++y)
    {
        // quarter circle
        int max_x = static_cast<int>(sqrt(R * R - y * y));
        for(int x = 1; x <= max_x; ++x)
        {
            const double l = sqrt(x*x + y*y);
            assert(l <= R);
 
            if(light_map(x0 + x, y0 + y)) d += 1. / l;
            if(light_map(x0 + x, y0 - y)) d += 1. / l;
            if(light_map(x0 - x, y0 - y)) d += 1. / l;
            if(light_map(x0 - x, y0 + y)) d += 1. / l;
        }
 
        // Vertical/Horizontal lines
        const double l = static_cast<double>(y);
        if(light_map(x0 + y, y0)) d += 1. / l;
        if(light_map(x0 - y, y0)) d += 1. / l;
        if(light_map(x0, y0 + y)) d += 1. / l;
        if(light_map(x0, y0 - y)) d += 1. / l;
    }
 
    // Central pix
    if(light_map(x0, y0)) d += 2 * sqrt(M_PI); // int_0^2pi int_0^1/sqrt(pi) 1/r dr r dphi
 
    return d;
}
 
// Everything is illuminated, independent of the landscape
// This is used to obtain the normalization factor
struct LightMapFull {
    LightMapFull() = default;
    bool operator()(int x, int y) const { return true; }
};
 
struct LightMapZoom {
    LightMapZoom(const C4Landscape& landscape, double sx, double sy):
        Landscape(landscape), sx(sx), sy(sy) {}
 
    // Returns whether zoomed coordinate is LightMap or not
    bool operator()(int x, int y) const
    {
        // Landscape coordinates
        const int lx = Clamp(static_cast<int>((x + 0.5) * sx), 0, Landscape.GetWidth() - 1);
        const int ly = Clamp(static_cast<int>((y + 0.5) * sy), 0, Landscape.GetHeight() - 1);
        // LightMap check
        return ::Landscape._GetLight(lx, ly);
    }
 
    const C4Landscape& Landscape;
    const double sx;
    const double sy;
};
 
} // anonymous namespace
 
C4FoWAmbient::C4FoWAmbient() = default;
 
C4FoWAmbient::~C4FoWAmbient()
{
    Clear();
}
 
void C4FoWAmbient::Clear()
{
#ifndef USE_CONSOLE
    if(Tex != 0) glDeleteTextures(1, &Tex);
    Tex = 0;
#endif
    Resolution = Radius = FullCoverage = 0.;
    SizeX = SizeY = 0;
    LandscapeX = LandscapeY = 0;
    Brightness = 1.;
}
 
void C4FoWAmbient::CreateFromLandscape(const C4Landscape& landscape, double resolution, double radius, double full_coverage)
{
    assert(resolution >= 1.);
    assert(radius >= 1.);
    assert(full_coverage > 0 && full_coverage <= 1.);
 
    // Clear old map
    Clear();
 
    Resolution = resolution;
    Radius = radius;
    FullCoverage = full_coverage;
 
    // Number of zoomed pixels
    LandscapeX = Landscape.GetWidth();
    LandscapeY = Landscape.GetHeight();
    SizeX = std::min<unsigned int>(static_cast<unsigned int>(ceil(LandscapeX / resolution)), pDraw->MaxTexSize);
    SizeY = std::min<unsigned int>(static_cast<unsigned int>(ceil(LandscapeY / resolution)), pDraw->MaxTexSize);
 
#ifndef USE_CONSOLE
    glGenTextures(1, &Tex);
    glBindTexture(GL_TEXTURE_2D, Tex);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, SizeX, SizeY, 0, GL_RED, GL_FLOAT, nullptr);
 
    const C4TimeMilliseconds begin = C4TimeMilliseconds::Now();
    UpdateFromLandscape(landscape, C4Rect(0, 0, Landscape.GetWidth(), Landscape.GetHeight()));
    uint32_t dt = C4TimeMilliseconds::Now() - begin;
    LogF("Created %ux%u ambient map in %g secs", SizeX, SizeY, dt / 1000.);
#endif
}
 
void C4FoWAmbient::UpdateFromLandscape(const C4Landscape& landscape, const C4Rect& update)
{
#ifndef USE_CONSOLE
    // Nothing to do?
    if(update.Wdt == 0 || update.Hgt == 0) return;
 
    assert(Tex != 0);
 
    // Factor to go from zoomed to landscape coordinates
    const double zoom_x = static_cast<double>(Landscape.GetWidth()) / SizeX;
    const double zoom_y = static_cast<double>(Landscape.GetHeight()) / SizeY;
    // Update region in zoomed coordinates
    const unsigned int left = std::max(static_cast<int>( (update.x - Radius) / zoom_x), 0);
    const unsigned int right = std::min(static_cast<unsigned int>( (update.x + update.Wdt + Radius) / zoom_x), SizeX - 1) + 1;
    const unsigned int top = std::max(static_cast<int>( (update.y - Radius) / zoom_y), 0);
    const unsigned int bottom = std::min(static_cast<unsigned int>( (update.y + update.Hgt + Radius) / zoom_y), SizeY - 1) + 1;
    assert(right > left);
    assert(bottom > top);
    // Zoomed radius
    const double R = Radius / sqrt(zoom_x * zoom_y);
    // Normalization factor with the full circle
    // The analytic result is 2*R*M_PI, and this number is typically close to it
    const double norm = AmbientForPix(0, 0, R, LightMapFull()) * FullCoverage;
    // Create the ambient map
    LightMapZoom light_mapZoom(landscape, zoom_x, zoom_y);
    float* ambient = new float[(right - left) * (bottom - top)];
    for(unsigned int y = top; y < bottom; ++y)
    {
        for(unsigned int x = left; x < right; ++x)
        {
            ambient[(y - top) * (right - left) + (x - left)] = std::min(AmbientForPix(x, y, R, light_mapZoom) / norm, 1.0);
        }
    }
 
#if 0
    CSurface8 debug(SizeX, SizeY);
    for(unsigned int y = 0; y < SizeY; ++y)
    {
        for(unsigned int x = 0; x < SizeX; ++x)
        {
            debug.SetPix(x, y, int(ambient[y * SizeX + x] * 255. + 0.5));
        }
    }
 
    CStdPalette pal;
    for(int i = 0; i < 256; ++i)
        pal.Colors[i] = i + (i << 8) + (i << 16);
    debug.Save("Ambient.bmp", &pal);
#endif
 
    // Update the texture
    glBindTexture(GL_TEXTURE_2D, Tex);
    glTexSubImage2D(GL_TEXTURE_2D, 0, left, top, (right - left), (bottom - top), GL_RED, GL_FLOAT, ambient);
    delete[] ambient;
#endif
}
 
void C4FoWAmbient::GetFragTransform(const FLOAT_RECT& vpRect, const C4Rect& clipRect, const C4Rect& outRect, float ambientTransform[6]) const
{
    C4FragTransform trans;
    // Invert Y coordinate
    trans.Scale(1, -1);
    trans.Translate(0, outRect.Hgt);
    // Clip offset
    trans.Translate(-clipRect.x, -clipRect.y);
    // Clip normalization (0,0 -> 1,1)
    trans.Scale(1.0f / clipRect.Wdt, 1.0f / clipRect.Hgt);
    // Viewport normalization
    trans.Scale(vpRect.right - vpRect.left, vpRect.bottom - vpRect.top);
    // Viewport offset
    trans.Translate(vpRect.left, vpRect.top);
    // Landscape normalization
    trans.Scale(1.0f / LandscapeX, 1.0f / LandscapeY);
 
    // Extract matrix
    trans.Get2x3(ambientTransform);
}