uses SDLh, uTypes, GLunit;

procedure initModule;

procedure freeModule;

procedure DrawRect              (rect: TSDL_Rect; r, g, b, a: Byte; Fill: boolean);

procedure RenderClear           ();

procedure RenderSetClearColor      (r, g, b, a: real);

procedure RenderSetup();

// TODO everything below this should not need a public interface

uses {$IFNDEF PAS2C} StrUtils, {$ENDIF}SysUtils, uVariables, uUtils, uConsts

     {$IFDEF GL2}, uMatrix, uConsole{$ENDIF};

{$IFDEF GL2}

var

    shaderMain: GLuint;

    shaderWater: GLuint;

{$ENDIF}

procedure RenderClear();

begin

    glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);

end;

procedure RenderSetClearColor(r, g, b, a: real);

begin

    glClearColor(r, g, b, a);

end;

{$IFDEF GL2}

function CompileShader(shaderFile: string; shaderType: GLenum): GLuint;

var

    shader: GLuint;

    f: Textfile;

    source, line: AnsiString;

    sourceA: Pchar;

    lengthA: GLint;

    compileResult: GLint;

    logLength: GLint;

    log: PChar;

begin

    Assign(f, PathPrefix + cPathz[ptShaders] + '/' + shaderFile);

    filemode:= 0; // readonly

    Reset(f);

    if IOResult <> 0 then

    begin

        AddFileLog('Unable to load ' + shaderFile);

        halt(-1);

    end;

    source:='';

    while not eof(f) do

    begin

        ReadLn(f, line);

        source:= source + line + #10;

    end;

    Close(f);

    WriteLnToConsole('Compiling shader: ' + PathPrefix + cPathz[ptShaders] + '/' + shaderFile);

    sourceA:=PChar(source);

    lengthA:=Length(source);

    shader:=glCreateShader(shaderType);

    glShaderSource(shader, 1, @sourceA, @lengthA);

    glCompileShader(shader);

    glGetShaderiv(shader, GL_COMPILE_STATUS, @compileResult);

    glGetShaderiv(shader, GL_INFO_LOG_LENGTH, @logLength);

    if logLength > 1 then

    begin

        log := GetMem(logLength);

        glGetShaderInfoLog(shader, logLength, nil, log);

        WriteLnToConsole('========== Compiler log  ==========');

        WriteLnToConsole(shortstring(log));

        WriteLnToConsole('===================================');

        FreeMem(log, logLength);

    end;

    if compileResult <> GL_TRUE then

    begin

        WriteLnToConsole('Shader compilation failed, halting');

        halt(-1);

    end;

    CompileShader:= shader;

end;

function CompileProgram(shaderName: string): GLuint;

var

    program_: GLuint;

    vs, fs: GLuint;

    linkResult: GLint;

    logLength: GLint;

    log: PChar;

begin

    program_:= glCreateProgram();

    vs:= CompileShader(shaderName + '.vs', GL_VERTEX_SHADER);

    fs:= CompileShader(shaderName + '.fs', GL_FRAGMENT_SHADER);

    glAttachShader(program_, vs);

    glAttachShader(program_, fs);

    glBindAttribLocation(program_, aVertex, PChar('vertex'));

    glBindAttribLocation(program_, aTexCoord, PChar('texcoord'));

    glBindAttribLocation(program_, aColor, PChar('color'));

    glLinkProgram(program_);

    glDeleteShader(vs);

    glDeleteShader(fs);

    glGetProgramiv(program_, GL_LINK_STATUS, @linkResult);

    glGetProgramiv(program_, GL_INFO_LOG_LENGTH, @logLength);

    if logLength > 1 then

    begin

        log := GetMem(logLength);

        glGetProgramInfoLog(program_, logLength, nil, log);

        WriteLnToConsole('========== Compiler log  ==========');

        WriteLnToConsole(shortstring(log));

        WriteLnToConsole('===================================');

        FreeMem(log, logLength);

    end;

    if linkResult <> GL_TRUE then

    begin

        WriteLnToConsole('Linking program failed, halting');

        halt(-1);

    end;

    CompileProgram:= program_;

end;

{$ENDIF}

procedure RenderSetup();

var AuxBufNum: LongInt = 0;

    tmpstr: ansistring;

    tmpint: LongInt;

    tmpn: LongInt;

begin

    // suppress hint/warning

    AuxBufNum:= AuxBufNum;

    // get the max (h and v) size for textures that the gpu can support

    glGetIntegerv(GL_MAX_TEXTURE_SIZE, @MaxTextureSize);

    if MaxTextureSize <= 0 then

        begin

        MaxTextureSize:= 1024;

        AddFileLog('OpenGL Warning - driver didn''t provide any valid max texture size; assuming 1024');

        end

    else if (MaxTextureSize < 1024) and (MaxTextureSize >= 512) then

        begin

        cReducedQuality := cReducedQuality or rqNoBackground;

        AddFileLog('Texture size too small for backgrounds, disabling.');

        end;

    // everyone loves debugging

    // find out which gpu we are using (for extension compatibility maybe?)

    AddFileLog('OpenGL-- Renderer: ' + shortstring(pchar(glGetString(GL_RENDERER))));

    AddFileLog('  |----- Vendor: ' + shortstring(pchar(glGetString(GL_VENDOR))));

    AddFileLog('  |----- Version: ' + shortstring(pchar(glGetString(GL_VERSION))));

    AddFileLog('  |----- Texture Size: ' + inttostr(MaxTextureSize));

{$IFDEF USE_VIDEO_RECORDING}

    glGetIntegerv(GL_AUX_BUFFERS, @AuxBufNum);

    AddFileLog('  |----- Number of auxiliary buffers: ' + inttostr(AuxBufNum));

{$ENDIF}

{$IFNDEF PAS2C}

    AddFileLog('  \----- Extensions: ');

    // fetch extentions and store them in string

    tmpstr := StrPas(PChar(glGetString(GL_EXTENSIONS)));

    tmpn := WordCount(tmpstr, [' ']);

    tmpint := 1;

    repeat

    begin

        // print up to 3 extentions per row

        // ExtractWord will return empty string if index out of range

        AddFileLog(TrimRight(

            ExtractWord(tmpint, tmpstr, [' ']) + ' ' +

            ExtractWord(tmpint+1, tmpstr, [' ']) + ' ' +

            ExtractWord(tmpint+2, tmpstr, [' '])

        ));

        tmpint := tmpint + 3;

    end;

    until (tmpint > tmpn);

{$ENDIF}

    AddFileLog('');

    defaultFrame:= 0;

{$IFDEF USE_VIDEO_RECORDING}

    if GameType = gmtRecord then

    begin

        if glLoadExtension('GL_EXT_framebuffer_object') then

        begin

            CreateFramebuffer(defaultFrame, depthv, texv);

            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, defaultFrame);

            AddFileLog('Using framebuffer for video recording.');

        end

        else if AuxBufNum > 0 then

        begin

            glDrawBuffer(GL_AUX0);

            glReadBuffer(GL_AUX0);

            AddFileLog('Using auxiliary buffer for video recording.');

        end

        else

        begin

            glDrawBuffer(GL_BACK);

            glReadBuffer(GL_BACK);

            AddFileLog('Warning: off-screen rendering is not supported; using back buffer but it may not work.');

        end;

    end;

{$ENDIF}

{$IFDEF GL2}

{$IFDEF PAS2C}

    err := glewInit();

    if err <> GLEW_OK then

    begin

        WriteLnToConsole('Failed to initialize GLEW.');

        halt;

    end;

{$ENDIF}

{$IFNDEF PAS2C}

    if not Load_GL_VERSION_2_0 then

        halt;

{$ENDIF}

    shaderWater:= CompileProgram('water');

    glUseProgram(shaderWater);

    glUniform1i(glGetUniformLocation(shaderWater, pchar('tex0')), 0);

    uWaterMVPLocation:= glGetUniformLocation(shaderWater, pchar('mvp'));

    shaderMain:= CompileProgram('default');

    glUseProgram(shaderMain);

    glUniform1i(glGetUniformLocation(shaderMain, pchar('tex0')), 0);

    uMainMVPLocation:= glGetUniformLocation(shaderMain, pchar('mvp'));

    uMainTintLocation:= glGetUniformLocation(shaderMain, pchar('tint'));

    uCurrentMVPLocation:= uMainMVPLocation;

    Tint(255, 255, 255, 255);

    UpdateModelviewProjection;

{$ENDIF}

{$IFNDEF USE_S3D_RENDERING}

    if (cStereoMode = smHorizontal) or (cStereoMode = smVertical) or (cStereoMode = smAFR) then

    begin

        // prepare left and right frame buffers and associated textures

        if glLoadExtension('GL_EXT_framebuffer_object') then

            begin

            CreateFramebuffer(framel, depthl, texl);

            CreateFramebuffer(framer, depthr, texr);

            // reset

            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, defaultFrame)

            end

        else

            cStereoMode:= smNone;

    end;

{$ENDIF}

// set view port to whole window

glViewport(0, 0, cScreenWidth, cScreenHeight);

{$IFDEF GL2}

    uMatrix.initModule;

    hglMatrixMode(MATRIX_MODELVIEW);

    // prepare default translation/scaling

    hglLoadIdentity();

    hglScalef(2.0 / cScreenWidth, -2.0 / cScreenHeight, 1.0);

    hglTranslatef(0, -cScreenHeight / 2, 0);

    EnableTexture(True);

    glEnableVertexAttribArray(aVertex);

    glEnableVertexAttribArray(aTexCoord);

    glGenBuffers(1, @vBuffer);

    glGenBuffers(1, @tBuffer);

    glGenBuffers(1, @cBuffer);

{$ELSE}

    glMatrixMode(GL_MODELVIEW);

    // prepare default translation/scaling

    glLoadIdentity();

    glScalef(2.0 / cScreenWidth, -2.0 / cScreenHeight, 1.0);

    glTranslatef(0, -cScreenHeight / 2, 0);

    // disable/lower perspective correction (will not need it anyway)

    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);

    // disable dithering

    glDisable(GL_DITHER);

    // enable common states by default as they save a lot

    glEnable(GL_TEXTURE_2D);

    glEnableClientState(GL_VERTEX_ARRAY);

    glEnableClientState(GL_TEXTURE_COORD_ARRAY);

{$ENDIF}

    // enable alpha blending

    glEnable(GL_BLEND);

    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    // disable/lower perspective correction (will not need it anyway)

end;