LOSTexture.cpp

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/* Copyright (C) 2012 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "precompiled.h"

#include "LOSTexture.h"

#include "graphics/ShaderManager.h"
#include "graphics/Terrain.h"
#include "lib/bits.h"
#include "ps/CLogger.h"
#include "ps/Game.h"
#include "ps/Profile.h"
#include "renderer/Renderer.h"
#include "renderer/TimeManager.h"
#include "simulation2/Simulation2.h"
#include "simulation2/components/ICmpRangeManager.h"
#include "simulation2/components/ICmpTerrain.h"

/*

The LOS bitmap is computed with one value per map vertex, based on
CCmpRangeManager's visibility information.

The bitmap is then blurred using an NxN filter (in particular a
7-tap Binomial filter as an efficient integral approximation of a Gaussian).
To implement the blur efficiently without using extra memory for a second copy
of the bitmap, we generate the bitmap with (N-1)/2 pixels of padding on each side,
then the blur shifts the image back into the corner.

The blurred bitmap is then uploaded into a GL texture for use by the renderer.

*/


// Blur with a NxN filter, where N = g_BlurSize must be an odd number.
static const size_t g_BlurSize = 7;

CLOSTexture::CLOSTexture(CSimulation2& simulation) :
    m_Simulation(simulation), m_Dirty(true), m_Texture(0), m_smoothFbo(0), m_MapSize(0), m_TextureSize(0), whichTex(true)
{
    if (CRenderer::IsInitialised() && g_Renderer.m_Options.m_SmoothLOS)
    {
        m_smoothShader = g_Renderer.GetShaderManager().LoadEffect(str_los_interp);
        CShaderProgramPtr shader = m_smoothShader->GetShader();

        if (m_smoothShader && shader)
        {
            pglGenFramebuffersEXT(1, &m_smoothFbo);
        }
        else
        {
            LOGERROR(L"Failed to load SmoothLOS shader, disabling.");
            g_Renderer.m_Options.m_SmoothLOS = false;
        }
    }
}

CLOSTexture::~CLOSTexture()
{
    if (m_Texture)
        DeleteTexture();
}

void CLOSTexture::DeleteTexture()
{
    glDeleteTextures(1, &m_Texture);
    if (CRenderer::IsInitialised() && g_Renderer.m_Options.m_SmoothLOS)
    {
        glDeleteTextures(1, &m_TextureSmooth1);
        glDeleteTextures(1, &m_TextureSmooth2);
    }
    m_Texture = 0;
}

void CLOSTexture::MakeDirty()
{
    m_Dirty = true;
}

void CLOSTexture::BindTexture(int unit)
{
    if (m_Dirty)
    {
        RecomputeTexture(unit);
        m_Dirty = false;
    }

    g_Renderer.BindTexture(unit, m_Texture);
}

GLuint CLOSTexture::GetTextureSmooth()
{
    if (CRenderer::IsInitialised() && !g_Renderer.m_Options.m_SmoothLOS)
        return GetTexture();
    else
        return whichTex ? m_TextureSmooth1 : m_TextureSmooth2;
}

void CLOSTexture::InterpolateLOS()
{
    if (CRenderer::IsInitialised() && !g_Renderer.m_Options.m_SmoothLOS)
        return;
    
    if (m_Dirty)
    {
        RecomputeTexture(0);
        m_Dirty = false;
    }
    
    GLint originalFBO;
    glGetIntegerv(GL_FRAMEBUFFER_BINDING_EXT, &originalFBO);
    
    pglBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_smoothFbo);
    pglFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, 
                   whichTex ? m_TextureSmooth2 : m_TextureSmooth1, 0);
    
    GLenum status = pglCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
    if (status != GL_FRAMEBUFFER_COMPLETE_EXT)
    {
        LOGWARNING(L"LOS framebuffer object incomplete: 0x%04X", status);
    }

    m_smoothShader->BeginPass();
    CShaderProgramPtr shader = m_smoothShader->GetShader();
    
    glDisable(GL_BLEND);
    
    shader->Bind();
    
    shader->BindTexture(str_losTex1, m_Texture);
    shader->BindTexture(str_losTex2, whichTex ? m_TextureSmooth1 : m_TextureSmooth2);
    
    shader->Uniform(str_delta, (float)g_Renderer.GetTimeManager().GetFrameDelta() * 4.0f, 0.0f, 0.0f, 0.0f);
    
    glPushAttrib(GL_VIEWPORT_BIT); 
    glViewport(0, 0, m_TextureSize, m_TextureSize);
    
    glBegin(GL_QUADS);
        glColor4f(1.f, 1.f, 1.f, 1.f);
        glTexCoord2f(1.0, 1.0); glVertex2f(1,1);
        glTexCoord2f(0.0, 1.0); glVertex2f(-1,1);       
        glTexCoord2f(0.0, 0.0); glVertex2f(-1,-1);
        glTexCoord2f(1.0, 0.0); glVertex2f(1,-1);
    glEnd();
    
    glPopAttrib(); 
    shader->Unbind();
    m_smoothShader->EndPass();
    
    pglFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, 0, 0);
    
    pglBindFramebufferEXT(GL_FRAMEBUFFER_EXT, originalFBO);
    
    whichTex = !whichTex;
}


GLuint CLOSTexture::GetTexture()
{
    if (m_Dirty)
    {
        RecomputeTexture(0);
        m_Dirty = false;
    }

    return m_Texture;
}

const CMatrix3D& CLOSTexture::GetTextureMatrix()
{
    ENSURE(!m_Dirty);
    return m_TextureMatrix;
}

const float* CLOSTexture::GetMinimapTextureMatrix()
{
    ENSURE(!m_Dirty);
    return &m_MinimapTextureMatrix._11;
}

void CLOSTexture::ConstructTexture(int unit)
{
    CmpPtr<ICmpTerrain> cmpTerrain(m_Simulation, SYSTEM_ENTITY);
    if (!cmpTerrain)
        return;

    m_MapSize = cmpTerrain->GetVerticesPerSide();

    m_TextureSize = (GLsizei)round_up_to_pow2((size_t)m_MapSize + g_BlurSize - 1);

    glGenTextures(1, &m_Texture);

    // Initialise texture with SoD colour, for the areas we don't
    // overwrite with glTexSubImage2D later
    u8* texData = new u8[m_TextureSize * m_TextureSize * 4];
    memset(texData, 0x00, m_TextureSize * m_TextureSize * 4);
    
    if (CRenderer::IsInitialised() && g_Renderer.m_Options.m_SmoothLOS)
    {
        glGenTextures(1, &m_TextureSmooth1);
        glGenTextures(1, &m_TextureSmooth2);
        
        g_Renderer.BindTexture(unit, m_TextureSmooth1);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_TextureSize, m_TextureSize, 0, GL_ALPHA, GL_UNSIGNED_BYTE, texData);
        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);

        g_Renderer.BindTexture(unit, m_TextureSmooth2);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_TextureSize, m_TextureSize, 0, GL_ALPHA, GL_UNSIGNED_BYTE, texData);
        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);
    }
    
    g_Renderer.BindTexture(unit, m_Texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, m_TextureSize, m_TextureSize, 0, GL_ALPHA, GL_UNSIGNED_BYTE, texData);
    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);
    
    delete[] texData;   
    
    {
        // Texture matrix: We want to map
        //   world pos (0, y, 0)  (i.e. first vertex)
        //     onto texcoord (0.5/texsize, 0.5/texsize)  (i.e. middle of first texel);
        //   world pos ((mapsize-1)*cellsize, y, (mapsize-1)*cellsize)  (i.e. last vertex)
        //     onto texcoord ((mapsize-0.5) / texsize, (mapsize-0.5) / texsize)  (i.e. middle of last texel)

        float s = (m_MapSize-1) / (float)(m_TextureSize * (m_MapSize-1) * TERRAIN_TILE_SIZE);
        float t = 0.5f / m_TextureSize;
        m_TextureMatrix.SetZero();
        m_TextureMatrix._11 = s;
        m_TextureMatrix._23 = s;
        m_TextureMatrix._14 = t;
        m_TextureMatrix._24 = t;
        m_TextureMatrix._44 = 1;
    }

    {
        // Minimap matrix: We want to map UV (0,0)-(1,1) onto (0,0)-(mapsize/texsize, mapsize/texsize)

        float s = m_MapSize / (float)m_TextureSize;
        m_MinimapTextureMatrix.SetZero();
        m_MinimapTextureMatrix._11 = s;
        m_MinimapTextureMatrix._22 = s;
        m_MinimapTextureMatrix._44 = 1;
    }
}

void CLOSTexture::RecomputeTexture(int unit)
{
    // If the map was resized, delete and regenerate the texture
    if (m_Texture)
    {
        CmpPtr<ICmpTerrain> cmpTerrain(m_Simulation, SYSTEM_ENTITY);
        if (cmpTerrain && m_MapSize != (ssize_t)cmpTerrain->GetVerticesPerSide())
            DeleteTexture();
    }

    bool recreated = false;
    if (!m_Texture)
    {
        ConstructTexture(unit);
        recreated = true;
    }

    PROFILE("recompute LOS texture");

    std::vector<u8> losData;
    losData.resize(GetBitmapSize(m_MapSize, m_MapSize));

    CmpPtr<ICmpRangeManager> cmpRangeManager(m_Simulation, SYSTEM_ENTITY);
    if (!cmpRangeManager)
        return;

    ICmpRangeManager::CLosQuerier los(cmpRangeManager->GetLosQuerier(g_Game->GetPlayerID()));

    GenerateBitmap(los, &losData[0], m_MapSize, m_MapSize);

    if (CRenderer::IsInitialised() && g_Renderer.m_Options.m_SmoothLOS && recreated)
    {
        g_Renderer.BindTexture(unit, m_TextureSmooth1);     
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, m_MapSize + g_BlurSize - 1, m_MapSize + g_BlurSize - 1, GL_ALPHA, GL_UNSIGNED_BYTE, &losData[0]);
        g_Renderer.BindTexture(unit, m_TextureSmooth2);     
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, m_MapSize + g_BlurSize - 1, m_MapSize + g_BlurSize - 1, GL_ALPHA, GL_UNSIGNED_BYTE, &losData[0]);
    }

    g_Renderer.BindTexture(unit, m_Texture);
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, m_MapSize + g_BlurSize - 1, m_MapSize + g_BlurSize - 1, GL_ALPHA, GL_UNSIGNED_BYTE, &losData[0]);
}

size_t CLOSTexture::GetBitmapSize(size_t w, size_t h)
{
    return (w + g_BlurSize - 1) * (h + g_BlurSize - 1);
}

void CLOSTexture::GenerateBitmap(ICmpRangeManager::CLosQuerier los, u8* losData, size_t w, size_t h)
{
    const size_t rowSize = w + g_BlurSize-1; // size of losData rows

    u8 *dataPtr = losData;

    // Initialise the top padding
    for (size_t j = 0; j < g_BlurSize/2; ++j)
        for (size_t i = 0; i < rowSize; ++i)
            *dataPtr++ = 0;

    for (size_t j = 0; j < h; ++j)
    {
        // Initialise the left padding
        for (size_t i = 0; i < g_BlurSize/2; ++i)
            *dataPtr++ = 0;

        // Fill in the visibility data
        for (size_t i = 0; i < w; ++i)
        {
            if (los.IsVisible_UncheckedRange(i, j))
                *dataPtr++ = 255;
            else if (los.IsExplored_UncheckedRange(i, j))
                *dataPtr++ = 127;
            else
                *dataPtr++ = 0;
        }

        // Initialise the right padding
        for (size_t i = 0; i < g_BlurSize/2; ++i)
            *dataPtr++ = 0;
    }

    // Initialise the bottom padding
    for (size_t j = 0; j < g_BlurSize/2; ++j)
        for (size_t i = 0; i < rowSize; ++i)
            *dataPtr++ = 0;

    // Horizontal blur:

    for (size_t j = g_BlurSize/2; j < h + g_BlurSize/2; ++j)
    {
        for (size_t i = 0; i < w; ++i)
        {
            u8* d = &losData[i+j*rowSize];
            *d = (
                1*d[0] +
                6*d[1] +
                15*d[2] +
                20*d[3] +
                15*d[4] +
                6*d[5] +
                1*d[6]
            ) / 64;
        }
    }

    // Vertical blur:

    for (size_t j = 0; j < h; ++j)
    {
        for (size_t i = 0; i < w; ++i)
        {
            u8* d = &losData[i+j*rowSize];
            *d = (
                1*d[0*rowSize] +
                6*d[1*rowSize] +
                15*d[2*rowSize] +
                20*d[3*rowSize] +
                15*d[4*rowSize] +
                6*d[5*rowSize] +
                1*d[6*rowSize]
            ) / 64;
        }
    }
}