Merge 'remotes/trunk'

[0ad.git] / source / renderer / OverlayRenderer.cpp

/* Copyright (C) 2015 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 "OverlayRenderer.h"

#include <boost/unordered_map.hpp>
#include "graphics/LOSTexture.h"
#include "graphics/Overlay.h"
#include "graphics/Terrain.h"
#include "graphics/TextureManager.h"
#include "lib/ogl.h"
#include "maths/MathUtil.h"
#include "maths/Quaternion.h"
#include "ps/Game.h"
#include "ps/Profile.h"
#include "renderer/Renderer.h"
#include "renderer/TexturedLineRData.h"
#include "renderer/VertexArray.h"
#include "renderer/VertexBuffer.h"
#include "renderer/VertexBufferManager.h"
#include "simulation2/Simulation2.h"
#include "simulation2/components/ICmpWaterManager.h"
#include "simulation2/system/SimContext.h"

/**
 * Key used to group quads into batches for more efficient rendering. Currently groups by the combination
 * of the main texture and the texture mask, to minimize texture swapping during rendering.
 */
struct QuadBatchKey
{
        QuadBatchKey (const CTexturePtr& texture, const CTexturePtr& textureMask)
                : m_Texture(texture), m_TextureMask(textureMask)
        { }

        bool operator==(const QuadBatchKey& other) const
        {
                return (m_Texture == other.m_Texture && m_TextureMask == other.m_TextureMask);
        }

        CTexturePtr m_Texture;
        CTexturePtr m_TextureMask;
};

/**
 * Holds information about a single quad rendering batch.
 */
class QuadBatchData : public CRenderData
{
public:
        QuadBatchData() : m_IndicesBase(0), m_NumRenderQuads(0) { }

        /// Holds the quad overlay structures requested to be rendered in this batch. Must be cleared
        /// after each frame.
        std::vector<SOverlayQuad*> m_Quads;

        /// Start index of this batch into the dedicated quad indices VertexArray (see OverlayInternals).
        size_t m_IndicesBase;
        /// Amount of quads to actually render in this batch. Potentially (although unlikely to be)
        /// different from m_Quads.size() due to restrictions on the total amount of quads that can be
        /// rendered. Must be reset after each frame.
        size_t m_NumRenderQuads;
};

struct OverlayRendererInternals
{
        typedef boost::unordered_map<QuadBatchKey, QuadBatchData> QuadBatchMap;

        OverlayRendererInternals();
        ~OverlayRendererInternals(){ }

        std::vector<SOverlayLine*> lines;
        std::vector<SOverlayTexturedLine*> texlines;
        std::vector<SOverlaySprite*> sprites;
        std::vector<SOverlayQuad*> quads;
        std::vector<SOverlaySphere*> spheres;

        QuadBatchMap quadBatchMap;

        // Dedicated vertex/index buffers for rendering all quads (to within the limits set by
        // MAX_QUAD_OVERLAYS).
        VertexArray quadVertices;
        VertexArray::Attribute quadAttributePos;
        VertexArray::Attribute quadAttributeColor;
        VertexArray::Attribute quadAttributeUV;
        VertexIndexArray quadIndices;

        /// Maximum amount of quad overlays we support for rendering. This limit is set to be able to
        /// render all quads from a single dedicated VB without having to reallocate it, which is much
        /// faster in the typical case of rendering only a handful of quads. When modifying this value,
        /// you must take care for the new amount of quads to fit in a single VBO (which is not likely
        /// to be a problem).
        static const size_t MAX_QUAD_OVERLAYS = 1024;

        // Sets of commonly-(re)used shader defines.
        CShaderDefines defsOverlayLineNormal;
        CShaderDefines defsOverlayLineAlwaysVisible;
        CShaderDefines defsQuadOverlay;

        // Geometry for a unit sphere
        std::vector<float> sphereVertexes;
        std::vector<u16> sphereIndexes;
        void GenerateSphere();

        /// Performs one-time setup. Called from CRenderer::Open, after graphics capabilities have
        /// been detected. Note that no VBOs must be created before this is called, since the shader
        /// path and graphics capabilities are not guaranteed to be stable before this point.
        void Initialize();
};

const float OverlayRenderer::OVERLAY_VOFFSET = 0.2f;

OverlayRendererInternals::OverlayRendererInternals()
        : quadVertices(GL_DYNAMIC_DRAW), quadIndices(GL_STATIC_DRAW)
{
        quadAttributePos.elems = 3;
        quadAttributePos.type = GL_FLOAT;
        quadVertices.AddAttribute(&quadAttributePos);

        quadAttributeColor.elems = 4;
        quadAttributeColor.type = GL_FLOAT;
        quadVertices.AddAttribute(&quadAttributeColor);

        quadAttributeUV.elems = 2;
        quadAttributeUV.type = GL_SHORT; // don't use GL_UNSIGNED_SHORT here, TexCoordPointer won't accept it
        quadVertices.AddAttribute(&quadAttributeUV);

        // Note that we're reusing the textured overlay line shader for the quad overlay rendering. This
        // is because their code is almost identical; the only difference is that for the quad overlays
        // we want to use a vertex color stream as opposed to an objectColor uniform. To this end, the
        // shader has been set up to switch between the two behaviours based on the USE_OBJECTCOLOR define.
        defsOverlayLineNormal.Add(str_USE_OBJECTCOLOR, str_1);
        defsOverlayLineAlwaysVisible.Add(str_USE_OBJECTCOLOR, str_1);
        defsOverlayLineAlwaysVisible.Add(str_IGNORE_LOS, str_1);
}

void OverlayRendererInternals::Initialize()
{
        // Perform any initialization after graphics capabilities have been detected. Notably,
        // only at this point can we safely allocate VBOs (in contrast to e.g. in the constructor),
        // because their creation depends on the shader path, which is not reliably set before this point.

        quadVertices.SetNumVertices(MAX_QUAD_OVERLAYS * 4);
        quadVertices.Layout(); // allocate backing store

        quadIndices.SetNumVertices(MAX_QUAD_OVERLAYS * 6);
        quadIndices.Layout(); // allocate backing store

        // Since the quads in the vertex array are independent and always consist of exactly 4 vertices per quad, the
        // indices are always the same; we can therefore fill in all the indices once and pretty much forget about
        // them. We then also no longer need its backing store, since we never change any indices afterwards.
        VertexArrayIterator<u16> index = quadIndices.GetIterator();
        for (size_t i = 0; i < MAX_QUAD_OVERLAYS; ++i)
        {
                *index++ = i*4 + 0;
                *index++ = i*4 + 1;
                *index++ = i*4 + 2;
                *index++ = i*4 + 2;
                *index++ = i*4 + 3;
                *index++ = i*4 + 0;
        }
        quadIndices.Upload();
        quadIndices.FreeBackingStore();
}

static size_t hash_value(const QuadBatchKey& d)
{
        size_t seed = 0;
        boost::hash_combine(seed, d.m_Texture);
        boost::hash_combine(seed, d.m_TextureMask);
        return seed;
}

OverlayRenderer::OverlayRenderer()
{
        m = new OverlayRendererInternals();
}

OverlayRenderer::~OverlayRenderer()
{
        delete m;
}

void OverlayRenderer::Initialize()
{
        m->Initialize();
}

void OverlayRenderer::Submit(SOverlayLine* line)
{
        ENSURE(line->m_Coords.size() % 3 == 0);

        m->lines.push_back(line);
}

void OverlayRenderer::Submit(SOverlayTexturedLine* line)
{
        // Simplify the rest of the code by guaranteeing non-empty lines
        if (line->m_Coords.empty())
                return;

        ENSURE(line->m_Coords.size() % 2 == 0);

        m->texlines.push_back(line);
}

void OverlayRenderer::Submit(SOverlaySprite* overlay)
{
        m->sprites.push_back(overlay);
}

void OverlayRenderer::Submit(SOverlayQuad* overlay)
{
        m->quads.push_back(overlay);
}

void OverlayRenderer::Submit(SOverlaySphere* overlay)
{
        m->spheres.push_back(overlay);
}

void OverlayRenderer::EndFrame()
{
        m->lines.clear();
        m->texlines.clear();
        m->sprites.clear();
        m->quads.clear();
        m->spheres.clear();

        // this should leave the capacity unchanged, which is okay since it
        // won't be very large or very variable

        // Empty the batch rendering data structures, but keep their key mappings around for the next frames
        for (OverlayRendererInternals::QuadBatchMap::iterator it = m->quadBatchMap.begin(); it != m->quadBatchMap.end(); ++it)
        {
                QuadBatchData& quadBatchData = (it->second);
                quadBatchData.m_Quads.clear();
                quadBatchData.m_NumRenderQuads = 0;
                quadBatchData.m_IndicesBase = 0;
        }
}

void OverlayRenderer::PrepareForRendering()
{
        PROFILE3("prepare overlays");

        // This is where we should do something like sort the overlays by
        // color/sprite/etc for more efficient rendering

        for (size_t i = 0; i < m->texlines.size(); ++i)
        {
                SOverlayTexturedLine* line = m->texlines[i];
                if (!line->m_RenderData)
                {
                        line->m_RenderData = shared_ptr<CTexturedLineRData>(new CTexturedLineRData());
                        line->m_RenderData->Update(*line);
                        // We assume the overlay line will get replaced by the caller
                        // if terrain changes, so we don't need to detect that here and
                        // call Update again. Also we assume the caller won't change
                        // any of the parameters after first submitting the line.
                }
        }

        // Group quad overlays by their texture/mask combination for efficient rendering
        // TODO: consider doing this directly in Submit()
        for (size_t i = 0; i < m->quads.size(); ++i)
        {
                SOverlayQuad* const quad = m->quads[i];

                QuadBatchKey textures(quad->m_Texture, quad->m_TextureMask);
                QuadBatchData& batchRenderData = m->quadBatchMap[textures]; // will create entry if it doesn't already exist

                // add overlay to list of quads
                batchRenderData.m_Quads.push_back(quad);
        }

        const CVector3D vOffset(0, OverlayRenderer::OVERLAY_VOFFSET, 0);

        // Write quad overlay vertices/indices to VA backing store
        VertexArrayIterator<CVector3D> vertexPos = m->quadAttributePos.GetIterator<CVector3D>();
        VertexArrayIterator<CVector4D> vertexColor = m->quadAttributeColor.GetIterator<CVector4D>();
        VertexArrayIterator<short[2]> vertexUV = m->quadAttributeUV.GetIterator<short[2]>();

        size_t indicesIdx = 0;
        size_t totalNumQuads = 0;

        for (OverlayRendererInternals::QuadBatchMap::iterator it = m->quadBatchMap.begin(); it != m->quadBatchMap.end(); ++it)
        {
                QuadBatchData& batchRenderData = (it->second);
                batchRenderData.m_NumRenderQuads = 0;

                if (batchRenderData.m_Quads.empty())
                        continue;

                // Remember the current index into the (entire) indices array as our base offset for this batch
                batchRenderData.m_IndicesBase = indicesIdx;

                // points to the index where each iteration's vertices will be appended
                for (size_t i = 0; i < batchRenderData.m_Quads.size() && totalNumQuads < OverlayRendererInternals::MAX_QUAD_OVERLAYS; i++)
                {
                        const SOverlayQuad* quad = batchRenderData.m_Quads[i];

                        // TODO: this is kind of ugly, the iterator should use a type that can have quad->m_Color assigned
                        // to it directly
                        const CVector4D quadColor(quad->m_Color.r, quad->m_Color.g, quad->m_Color.b, quad->m_Color.a);

                        *vertexPos++ = quad->m_Corners[0] + vOffset;
                        *vertexPos++ = quad->m_Corners[1] + vOffset;
                        *vertexPos++ = quad->m_Corners[2] + vOffset;
                        *vertexPos++ = quad->m_Corners[3] + vOffset;

                        (*vertexUV)[0] = 0;
                        (*vertexUV)[1] = 0;
                        ++vertexUV;
                        (*vertexUV)[0] = 0;
                        (*vertexUV)[1] = 1;
                        ++vertexUV;
                        (*vertexUV)[0] = 1;
                        (*vertexUV)[1] = 1;
                        ++vertexUV;
                        (*vertexUV)[0] = 1;
                        (*vertexUV)[1] = 0;
                        ++vertexUV;

                        *vertexColor++ = quadColor;
                        *vertexColor++ = quadColor;
                        *vertexColor++ = quadColor;
                        *vertexColor++ = quadColor;

                        indicesIdx += 6;

                        totalNumQuads++;
                        batchRenderData.m_NumRenderQuads++;
                }
        }

        m->quadVertices.Upload();
        // don't free the backing store! we'll overwrite it on the next frame to save a reallocation.

        m->quadVertices.PrepareForRendering();
}

void OverlayRenderer::RenderOverlaysBeforeWater()
{
        PROFILE3_GPU("overlays (before)");

#if CONFIG2_GLES
#warning TODO: implement OverlayRenderer::RenderOverlaysBeforeWater for GLES
#else
        pglActiveTextureARB(GL_TEXTURE0);
        glDisable(GL_TEXTURE_2D);
        glEnable(GL_BLEND);

        // Ignore z so that we draw behind terrain (but don't disable GL_DEPTH_TEST
        // since we still want to write to the z buffer)
        glDepthFunc(GL_ALWAYS);

        for (size_t i = 0; i < m->lines.size(); ++i)
        {
                SOverlayLine* line = m->lines[i];
                if (line->m_Coords.empty())
                        continue;

                ENSURE(line->m_Coords.size() % 3 == 0);

                glColor4fv(line->m_Color.FloatArray());
                glLineWidth((float)line->m_Thickness);

                glInterleavedArrays(GL_V3F, sizeof(float)*3, &line->m_Coords[0]);
                glDrawArrays(GL_LINE_STRIP, 0, (GLsizei)line->m_Coords.size()/3);
        }

        glDisableClientState(GL_VERTEX_ARRAY);

        glLineWidth(1.f);
        glDepthFunc(GL_LEQUAL);
        glDisable(GL_BLEND);
#endif
}

void OverlayRenderer::RenderOverlaysAfterWater()
{
        PROFILE3_GPU("overlays (after)");

        RenderTexturedOverlayLines();
        RenderQuadOverlays();
        RenderSphereOverlays();
}

void OverlayRenderer::RenderTexturedOverlayLines()
{
#if CONFIG2_GLES
#warning TODO: implement OverlayRenderer::RenderTexturedOverlayLines for GLES
        return;
#endif
        if (m->texlines.empty())
                return;

        ogl_WarnIfError();

        pglActiveTextureARB(GL_TEXTURE0);
        glEnable(GL_TEXTURE_2D);
        glEnable(GL_BLEND);
        glDepthMask(0);

        const char* shaderName;
        if (g_Renderer.GetRenderPath() == CRenderer::RP_SHADER)
                shaderName = "arb/overlayline";
        else
                shaderName = "fixed:overlayline";

        CLOSTexture& los = g_Renderer.GetScene().GetLOSTexture();

        CShaderManager& shaderManager = g_Renderer.GetShaderManager();
        CShaderProgramPtr shaderTexLineNormal(shaderManager.LoadProgram(shaderName, m->defsOverlayLineNormal));
        CShaderProgramPtr shaderTexLineAlwaysVisible(shaderManager.LoadProgram(shaderName, m->defsOverlayLineAlwaysVisible));

        // ----------------------------------------------------------------------------------------

        if (shaderTexLineNormal)
        {
                shaderTexLineNormal->Bind();
                shaderTexLineNormal->BindTexture(str_losTex, los.GetTexture());
                shaderTexLineNormal->Uniform(str_losTransform, los.GetTextureMatrix()[0], los.GetTextureMatrix()[12], 0.f, 0.f);

                // batch render only the non-always-visible overlay lines using the normal shader
                RenderTexturedOverlayLines(shaderTexLineNormal, false);

                shaderTexLineNormal->Unbind();
        }

        // ----------------------------------------------------------------------------------------

        if (shaderTexLineAlwaysVisible)
        {
                shaderTexLineAlwaysVisible->Bind();
                // TODO: losTex and losTransform are unused in the always visible shader; see if these can be safely omitted
                shaderTexLineAlwaysVisible->BindTexture(str_losTex, los.GetTexture());
                shaderTexLineAlwaysVisible->Uniform(str_losTransform, los.GetTextureMatrix()[0], los.GetTextureMatrix()[12], 0.f, 0.f);

                // batch render only the always-visible overlay lines using the LoS-ignored shader
                RenderTexturedOverlayLines(shaderTexLineAlwaysVisible, true);

                shaderTexLineAlwaysVisible->Unbind();
        }

        // ----------------------------------------------------------------------------------------

        // TODO: the shaders should probably be responsible for unbinding their textures
        g_Renderer.BindTexture(1, 0);
        g_Renderer.BindTexture(0, 0);

        CVertexBuffer::Unbind();

        glDepthMask(1);
        glDisable(GL_BLEND);
}

void OverlayRenderer::RenderTexturedOverlayLines(CShaderProgramPtr shader, bool alwaysVisible)
{
        for (size_t i = 0; i < m->texlines.size(); ++i)
        {
                SOverlayTexturedLine* line = m->texlines[i];

                // render only those lines matching the requested alwaysVisible status
                if (!line->m_RenderData || line->m_AlwaysVisible != alwaysVisible)
                        continue;

                ENSURE(line->m_RenderData);
                line->m_RenderData->Render(*line, shader);
        }
}

void OverlayRenderer::RenderQuadOverlays()
{
#if CONFIG2_GLES
#warning TODO: implement OverlayRenderer::RenderQuadOverlays for GLES
        return;
#endif
        if (m->quadBatchMap.empty())
                return;

        ogl_WarnIfError();

        pglActiveTextureARB(GL_TEXTURE0);
        glEnable(GL_TEXTURE_2D);
        glEnable(GL_BLEND);
        glDepthMask(0);

        const char* shaderName;
        if (g_Renderer.GetRenderPath() == CRenderer::RP_SHADER)
                shaderName = "arb/overlayline";
        else
                shaderName = "fixed:overlayline";

        CLOSTexture& los = g_Renderer.GetScene().GetLOSTexture();

        CShaderManager& shaderManager = g_Renderer.GetShaderManager();
        CShaderProgramPtr shader(shaderManager.LoadProgram(shaderName, m->defsQuadOverlay));

        // ----------------------------------------------------------------------------------------

        if (shader)
        {
                shader->Bind();
                shader->BindTexture(str_losTex, los.GetTexture());
                shader->Uniform(str_losTransform, los.GetTextureMatrix()[0], los.GetTextureMatrix()[12], 0.f, 0.f);

                // Base offsets (in bytes) of the two backing stores relative to their owner VBO
                u8* indexBase = m->quadIndices.Bind();
                u8* vertexBase = m->quadVertices.Bind();
                GLsizei indexStride = m->quadIndices.GetStride();
                GLsizei vertexStride = m->quadVertices.GetStride();

                for (OverlayRendererInternals::QuadBatchMap::iterator it = m->quadBatchMap.begin(); it != m->quadBatchMap.end(); ++it)
                {
                        QuadBatchData& batchRenderData = it->second;
                        const size_t batchNumQuads = batchRenderData.m_NumRenderQuads;

                        // Careful; some drivers don't like drawing calls with 0 stuff to draw.
                        if (batchNumQuads == 0)
                                continue;

                        const QuadBatchKey& maskPair = it->first;

                        shader->BindTexture(str_baseTex, maskPair.m_Texture->GetHandle());
                        shader->BindTexture(str_maskTex, maskPair.m_TextureMask->GetHandle());

                        int streamflags = shader->GetStreamFlags();

                        if (streamflags & STREAM_POS)
                                shader->VertexPointer(m->quadAttributePos.elems, m->quadAttributePos.type, vertexStride, vertexBase + m->quadAttributePos.offset);

                        if (streamflags & STREAM_UV0)
                                shader->TexCoordPointer(GL_TEXTURE0, m->quadAttributeUV.elems, m->quadAttributeUV.type, vertexStride, vertexBase + m->quadAttributeUV.offset);

                        if (streamflags & STREAM_UV1)
                                shader->TexCoordPointer(GL_TEXTURE1, m->quadAttributeUV.elems, m->quadAttributeUV.type, vertexStride, vertexBase + m->quadAttributeUV.offset);

                        if (streamflags & STREAM_COLOR)
                                shader->ColorPointer(m->quadAttributeColor.elems, m->quadAttributeColor.type, vertexStride, vertexBase + m->quadAttributeColor.offset);

                        shader->AssertPointersBound();
                        glDrawElements(GL_TRIANGLES, (GLsizei)(batchNumQuads * 6), GL_UNSIGNED_SHORT, indexBase + indexStride * batchRenderData.m_IndicesBase);

                        g_Renderer.GetStats().m_DrawCalls++;
                        g_Renderer.GetStats().m_OverlayTris += batchNumQuads*2;
                }

                shader->Unbind();
        }

        // ----------------------------------------------------------------------------------------

        // TODO: the shader should probably be responsible for unbinding its textures
        g_Renderer.BindTexture(1, 0);
        g_Renderer.BindTexture(0, 0);

        CVertexBuffer::Unbind();

        glDepthMask(1);
        glDisable(GL_BLEND);
}

void OverlayRenderer::RenderForegroundOverlays(const CCamera& viewCamera)
{
        PROFILE3_GPU("overlays (fg)");

#if CONFIG2_GLES
#warning TODO: implement OverlayRenderer::RenderForegroundOverlays for GLES
#else
        pglActiveTextureARB(GL_TEXTURE0);
        glEnable(GL_TEXTURE_2D);
        glEnable(GL_BLEND);
        glDisable(GL_DEPTH_TEST);

        CVector3D right = -viewCamera.m_Orientation.GetLeft();
        CVector3D up = viewCamera.m_Orientation.GetUp();

        glColor4f(1.0f, 1.0f, 1.0f, 1.0f);

        glEnableClientState(GL_VERTEX_ARRAY);
        glEnableClientState(GL_TEXTURE_COORD_ARRAY);

        CShaderProgramPtr shader;
        CShaderTechniquePtr tech;

        if (g_Renderer.GetRenderPath() == CRenderer::RP_SHADER)
        {
                tech = g_Renderer.GetShaderManager().LoadEffect(str_foreground_overlay);
                tech->BeginPass();
                shader = tech->GetShader();
        }

        float uvs[8] = { 0,1, 1,1, 1,0, 0,0 };

        if (g_Renderer.GetRenderPath() == CRenderer::RP_SHADER)
                shader->TexCoordPointer(GL_TEXTURE0, 2, GL_FLOAT, sizeof(float)*2, &uvs[0]);
        else
                glTexCoordPointer(2, GL_FLOAT, sizeof(float)*2, &uvs);

        for (size_t i = 0; i < m->sprites.size(); ++i)
        {
                SOverlaySprite* sprite = m->sprites[i];

                if (g_Renderer.GetRenderPath() == CRenderer::RP_SHADER)
                        shader->BindTexture(str_baseTex, sprite->m_Texture);
                else
                        sprite->m_Texture->Bind();

                shader->Uniform(str_colorMul, sprite->m_Color);

                CVector3D pos[4] = {
                        sprite->m_Position + right*sprite->m_X0 + up*sprite->m_Y0,
                        sprite->m_Position + right*sprite->m_X1 + up*sprite->m_Y0,
                        sprite->m_Position + right*sprite->m_X1 + up*sprite->m_Y1,
                        sprite->m_Position + right*sprite->m_X0 + up*sprite->m_Y1
                };

                if (g_Renderer.GetRenderPath() == CRenderer::RP_SHADER)
                        shader->VertexPointer(3, GL_FLOAT, sizeof(float)*3, &pos[0].X);
                else
                        glVertexPointer(3, GL_FLOAT, sizeof(float)*3, &pos[0].X);

                glDrawArrays(GL_QUADS, 0, (GLsizei)4);

                g_Renderer.GetStats().m_DrawCalls++;
                g_Renderer.GetStats().m_OverlayTris += 2;
        }

        if (g_Renderer.GetRenderPath() == CRenderer::RP_SHADER)
                tech->EndPass();

        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY);

        glEnable(GL_DEPTH_TEST);
        glDisable(GL_BLEND);
        glDisable(GL_TEXTURE_2D);
#endif
}

static void TessellateSphereFace(const CVector3D& a, u16 ai,
                                                                 const CVector3D& b, u16 bi,
                                                                 const CVector3D& c, u16 ci,
                                                                 std::vector<float>& vertexes, std::vector<u16>& indexes, int level)
{
        if (level == 0)
        {
                indexes.push_back(ai);
                indexes.push_back(bi);
                indexes.push_back(ci);
        }
        else
        {
                CVector3D d = (a + b).Normalized();
                CVector3D e = (b + c).Normalized();
                CVector3D f = (c + a).Normalized();
                int di = vertexes.size() / 3; vertexes.push_back(d.X); vertexes.push_back(d.Y); vertexes.push_back(d.Z);
                int ei = vertexes.size() / 3; vertexes.push_back(e.X); vertexes.push_back(e.Y); vertexes.push_back(e.Z);
                int fi = vertexes.size() / 3; vertexes.push_back(f.X); vertexes.push_back(f.Y); vertexes.push_back(f.Z);
                TessellateSphereFace(a,ai, d,di, f,fi, vertexes, indexes, level-1);
                TessellateSphereFace(d,di, b,bi, e,ei, vertexes, indexes, level-1);
                TessellateSphereFace(f,fi, e,ei, c,ci, vertexes, indexes, level-1);
                TessellateSphereFace(d,di, e,ei, f,fi, vertexes, indexes, level-1);
        }
}

static void TessellateSphere(std::vector<float>& vertexes, std::vector<u16>& indexes, int level)
{
        /* Start with a tetrahedron, then tessellate */
        float s = sqrtf(0.5f);
#define VERT(a,b,c) vertexes.push_back(a); vertexes.push_back(b); vertexes.push_back(c);
        VERT(-s,  0, -s);
        VERT( s,  0, -s);
        VERT( s,  0,  s);
        VERT(-s,  0,  s);
        VERT( 0, -1,  0);
        VERT( 0,  1,  0);
#define FACE(a,b,c) \
        TessellateSphereFace( \
                CVector3D(vertexes[a*3], vertexes[a*3+1], vertexes[a*3+2]), a, \
                CVector3D(vertexes[b*3], vertexes[b*3+1], vertexes[b*3+2]), b, \
                CVector3D(vertexes[c*3], vertexes[c*3+1], vertexes[c*3+2]), c, \
                vertexes, indexes, level);
        FACE(0,4,1);
        FACE(1,4,2);
        FACE(2,4,3);
        FACE(3,4,0);
        FACE(1,5,0);
        FACE(2,5,1);
        FACE(3,5,2);
        FACE(0,5,3);
#undef FACE
#undef VERT
}

void OverlayRendererInternals::GenerateSphere()
{
        if (sphereVertexes.empty())
                TessellateSphere(sphereVertexes, sphereIndexes, 3);
}

void OverlayRenderer::RenderSphereOverlays()
{
        PROFILE3_GPU("overlays (spheres)");

#if CONFIG2_GLES
#warning TODO: implement OverlayRenderer::RenderSphereOverlays for GLES
#else
        if (g_Renderer.GetRenderPath() != CRenderer::RP_SHADER)
                return;

        if (m->spheres.empty())
                return;

        glDisable(GL_TEXTURE_2D);
        glEnable(GL_BLEND);
        glDepthMask(0);

        glEnableClientState(GL_VERTEX_ARRAY);

        CShaderProgramPtr shader;
        CShaderTechniquePtr tech;

        tech = g_Renderer.GetShaderManager().LoadEffect(str_overlay_solid);
        tech->BeginPass();
        shader = tech->GetShader();

        m->GenerateSphere();

        shader->VertexPointer(3, GL_FLOAT, 0, &m->sphereVertexes[0]);

        for (size_t i = 0; i < m->spheres.size(); ++i)
        {
                SOverlaySphere* sphere = m->spheres[i];

                CMatrix3D transform;
                transform.SetIdentity();
                transform.Scale(sphere->m_Radius, sphere->m_Radius, sphere->m_Radius);
                transform.Translate(sphere->m_Center);

                shader->Uniform(str_transform, transform);

                shader->Uniform(str_color, sphere->m_Color);

                glDrawElements(GL_TRIANGLES, m->sphereIndexes.size(), GL_UNSIGNED_SHORT, &m->sphereIndexes[0]);

                g_Renderer.GetStats().m_DrawCalls++;
                g_Renderer.GetStats().m_OverlayTris = m->sphereIndexes.size()/3;
        }

        tech->EndPass();

        glDisableClientState(GL_VERTEX_ARRAY);

        glDepthMask(1);
        glDisable(GL_BLEND);
#endif
}