3D C/C++ tutorials - OpenGL 2.1 - Deferred rendering - Antialiasing
3D C/C++ tutorials -> OpenGL 2.1 -> Deferred rendering - Antialiasing
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To compile and run these tutorials some or all of these libraries are required: FreeImage 3.16.0, GLEW 1.11.0, GLUT 3.7.6 / GLUT for Dev-C++, GLM 0.9.5.4
opengl_21_tutorials_win32_framework.h
...

class COpenGLRenderer
{
protected:
    ...
    mat4x4 ..., ProjectionBiasMatrixInverse;

protected:
    CTexture Texture[3];
    CShaderProgram Preprocess, DeferredLighting, Antialiasing;
    GLuint ColorBuffers[2], NormalBuffer, DepthBuffer;
    GLuint VBO, FBO;

public:
    bool CalculateAntialiasing, Pause;
    vec3 LightColors[4], LightPositions[4];

public:
    ...

protected:
    void InitArrayBuffers();
};

...
opengl_21_tutorials_win32_framework.cpp
...

COpenGLRenderer::COpenGLRenderer()
{
    CalculateAntialiasing = true;

    Pause = false;

    Camera.SetViewMatrixPointer(&ViewMatrix);
}

COpenGLRenderer::~COpenGLRenderer()
{
}

bool COpenGLRenderer::Init()
{
    // ------------------------------------------------------------------------------------------------------------------------

    bool Error = false;

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

    if(!GLEW_ARB_texture_non_power_of_two)
    {
        ErrorLog.Append("GL_ARB_texture_non_power_of_two not supported!\r\n");
        Error = true;
    }

    if(!GLEW_ARB_depth_texture)
    {
        ErrorLog.Append("GLEW_ARB_depth_texture not supported!\r\n");
        Error = true;
    }

    if(!GLEW_EXT_framebuffer_object)
    {
        ErrorLog.Append("GL_EXT_framebuffer_object not supported!\r\n");
        Error = true;
    }

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

    char *TextureFileName[] = {"cube.jpg", "floor.jpg", "wall.jpg"};

    for(int i = 0; i < 3; i++)
    {
        Error |= !Texture[i].LoadTexture2D(TextureFileName[i]);
    }

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

    Error |= !Preprocess.Load("preprocess.vs", "preprocess.fs");
    Error |= !DeferredLighting.Load("deferredlighting.vs", "deferredlighting.fs");
    Error |= !Antialiasing.Load("antialiasing.vs", "antialiasing.fs");

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

    if(Error)
    {
        return false;
    }

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

    Preprocess.UniformLocations = new GLuint[1];
    Preprocess.UniformLocations[0] = glGetUniformLocation(Preprocess, "Texturing");

    DeferredLighting.UniformLocations = new GLuint[1];
    DeferredLighting.UniformLocations[0] = glGetUniformLocation(DeferredLighting, "ProjectionBiasMatrixInverse");

    Antialiasing.UniformLocations = new GLuint[1];
    Antialiasing.UniformLocations[0] = glGetUniformLocation(Antialiasing, "PixelSize");

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

    glUseProgram(DeferredLighting);
    glUniform1i(glGetUniformLocation(DeferredLighting, "ColorBuffer"), 0);
    glUniform1i(glGetUniformLocation(DeferredLighting, "NormalBuffer"), 1);
    glUniform1i(glGetUniformLocation(DeferredLighting, "DepthBuffer"), 2);
    glUseProgram(0);
    
    glUseProgram(Antialiasing);
    glUniform1i(glGetUniformLocation(Antialiasing, "ColorBuffer"), 0);
    glUniform1i(glGetUniformLocation(Antialiasing, "NormalBuffer"), 1);
    glUniform1i(glGetUniformLocation(Antialiasing, "DepthBuffer"), 2);
    glUseProgram(0);

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

    glGenTextures(2, ColorBuffers);
    glGenTextures(1, &NormalBuffer);
    glGenTextures(1, &DepthBuffer);

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

    glGenBuffers(1, &VBO);

    InitArrayBuffers();

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

    glGenFramebuffersEXT(1, &FBO);

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

    LightColors[0] = vec3(1.0f, 0.0f, 0.0f);
    LightPositions[0] = vec3(0.0f, 1.5f, 0.33f);
    LightColors[1] = vec3(0.0f, 1.0f, 0.0f);
    LightPositions[1] = rotate(LightPositions[0], 120.0f, vec3(0.0f, 1.0f, 0.0f));
    LightColors[2] = vec3(0.0f, 0.0f, 1.0f);
    LightPositions[2] = rotate(LightPositions[1], 120.0f, vec3(0.0f, 1.0f, 0.0f));
    LightColors[3] = vec3(1.0f, 1.0f, 1.0f);
    LightPositions[3] = vec3(0.0f, 2.75f, -4.75f);

    for(int i = 0; i < 3; i++)
    {
        glLightfv(GL_LIGHT0 + i, GL_AMBIENT, &vec4(LightColors[i] * 0.125f, 1.0f));
        glLightfv(GL_LIGHT0 + i, GL_DIFFUSE, &vec4(LightColors[i] * 0.875f, 1.0f));
        glLightf(GL_LIGHT0 + i, GL_LINEAR_ATTENUATION, 1.0f);
        glLightf(GL_LIGHT0 + i, GL_QUADRATIC_ATTENUATION, 1.0f);
    }

    glLightfv(GL_LIGHT3, GL_AMBIENT, &vec4(LightColors[3] * 0.25f, 1.0f));
    glLightfv(GL_LIGHT3, GL_DIFFUSE, &vec4(LightColors[3] * 0.75f, 1.0f));
    glLightf(GL_LIGHT3, GL_LINEAR_ATTENUATION, 1.0f / 32.0f);
    glLightf(GL_LIGHT3, GL_QUADRATIC_ATTENUATION, 1.0f / 64.0f);

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

    Camera.Look(vec3(0.0f, 1.75f, 1.875f), vec3(0.0f, 1.5f, 0.0f));

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

    return true;

    // ------------------------------------------------------------------------------------------------------------------------
}

void COpenGLRenderer::Render(float FrameTime)
{
    // ------------------------------------------------------------------------------------------------------------------------

    GLenum Buffers[] = {GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT};

    // render scene to textures -----------------------------------------------------------------------------------------------

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, FBO);
    glDrawBuffers(2, Buffers); glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, ColorBuffers[0], 0);
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_TEXTURE_2D, NormalBuffer, 0);
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_TEXTURE_2D, DepthBuffer, 0);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);
    glLoadMatrixf(&ViewMatrix);

    glEnable(GL_DEPTH_TEST);
    glEnable(GL_CULL_FACE);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);

    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glTexCoordPointer(2, GL_FLOAT, 32, (void*)0);

    glEnableClientState(GL_NORMAL_ARRAY);
    glNormalPointer(GL_FLOAT, 32, (void*)8);

    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(3, GL_FLOAT, 32, (void*)20);

    glUseProgram(Preprocess);
    
    glUniform1i(Preprocess.UniformLocations[0], true);

    glColor3f(1.0f, 1.0f, 1.0f);

    glBindTexture(GL_TEXTURE_2D, Texture[0]);
    glDrawArrays(GL_QUADS, 0, 96);

    glBindTexture(GL_TEXTURE_2D, Texture[1]);
    glDrawArrays(GL_QUADS, 96, 4);

    glBindTexture(GL_TEXTURE_2D, Texture[2]);
    glDrawArrays(GL_QUADS, 100, 80);

    glBindTexture(GL_TEXTURE_2D, 0);

    glUniform1i(Preprocess.UniformLocations[0], false);

    glDrawArrays(GL_QUADS, 180, 4);

    glMultMatrixf(&ModelMatrix);
    glColor3f(0.33f, 0.66f, 1.0f);
    glDrawArrays(GL_QUADS, 184, 72);

    glUseProgram(0);

    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_NORMAL_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    glDisable(GL_CULL_FACE);
    glDisable(GL_DEPTH_TEST);

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    // set lights positions ------------------------------------------------------------------------------------------------------------------------

    glMatrixMode(GL_MODELVIEW);
    glLoadMatrixf(&ViewMatrix);

    for(int i = 0; i < 4; i++)
    {
        glLightfv(GL_LIGHT0 + i, GL_POSITION, &vec4(LightPositions[i], 1.0f));
    }

    // calculate lighting -----------------------------------------------------------------------------------------------------

    if(CalculateAntialiasing)
    {
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, FBO);
        glDrawBuffers(1, Buffers); glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, ColorBuffers[1], 0);
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_TEXTURE_2D, 0, 0);
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_TEXTURE_2D, 0, 0);
    }

    glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, ColorBuffers[0]);
    glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, NormalBuffer);
    glActiveTexture(GL_TEXTURE2); glBindTexture(GL_TEXTURE_2D, DepthBuffer);
    glUseProgram(DeferredLighting);
    glBegin(GL_QUADS);
        glVertex2f(0.0f, 0.0f);
        glVertex2f(1.0f, 0.0f);
        glVertex2f(1.0f, 1.0f);
        glVertex2f(0.0f, 1.0f);
    glEnd();
    glUseProgram(0);
    glActiveTexture(GL_TEXTURE2); glBindTexture(GL_TEXTURE_2D, 0);
    glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, 0);
    glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, 0);
    
    if(CalculateAntialiasing)
    {
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
    }

    // calculate antialiasing -------------------------------------------------------------------------------------------------

    if(CalculateAntialiasing)
    {
        glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, ColorBuffers[1]);
        glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, NormalBuffer);
        glActiveTexture(GL_TEXTURE2); glBindTexture(GL_TEXTURE_2D, DepthBuffer);
        glUseProgram(Antialiasing);
        glBegin(GL_QUADS);
            glVertex2f(0.0f, 0.0f);
            glVertex2f(1.0f, 0.0f);
            glVertex2f(1.0f, 1.0f);
            glVertex2f(0.0f, 1.0f);
        glEnd();
        glUseProgram(0);
        glActiveTexture(GL_TEXTURE2); glBindTexture(GL_TEXTURE_2D, 0);
        glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, 0);
        glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, 0);
    }

    // rotate object and lights -----------------------------------------------------------------------------------------------

    if(!Pause)
    {
        static float a = 0.0f;

        ModelMatrix = translate(0.0f, 1.5f, 0.0f) * rotate(a, vec3(0.0f, 1.0f, 0.0f)) * rotate(a, vec3(1.0f, 0.0f, 0.0f));

        a += 22.5f * FrameTime;

        for(int i = 0; i < 3; i++)
        {
            LightPositions[i] = rotate(LightPositions[i], -180.0f * FrameTime, vec3(0.0f, 1.0f, 0.0f));
        }
    }

    // ------------------------------------------------------------------------------------------------------------------------
}

void COpenGLRenderer::Resize(int Width, int Height)
{
    this->Width = Width;
    this->Height = Height;

    glViewport(0, 0, Width, Height);

    ProjectionMatrix = perspective(45.0f, (float)Width / (float)Height, 0.125f, 512.0f);

    glMatrixMode(GL_PROJECTION);
    glLoadMatrixf(&ProjectionMatrix);

    ProjectionBiasMatrixInverse = inverse(ProjectionMatrix) * BiasMatrixInverse;

    for(int i = 0; i < 2; i++)
    {
        glBindTexture(GL_TEXTURE_2D, ColorBuffers[i]);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, Width, Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
        glBindTexture(GL_TEXTURE_2D, 0);
    }

    glBindTexture(GL_TEXTURE_2D, NormalBuffer);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, Width, Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
    glBindTexture(GL_TEXTURE_2D, 0);

    glBindTexture(GL_TEXTURE_2D, DepthBuffer);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT24, Width, Height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
    glBindTexture(GL_TEXTURE_2D, 0);

    glUseProgram(DeferredLighting);
    glUniformMatrix4fv(DeferredLighting.UniformLocations[0], 1, GL_FALSE, &ProjectionBiasMatrixInverse);
    glUseProgram(0);

    glUseProgram(Antialiasing);
    glUniform2f(Antialiasing.UniformLocations[0], 1.0f / (float)Width, 1.0f / (float)Height);
    glUseProgram(0);
}

void COpenGLRenderer::Destroy()
{
    for(int i = 0; i < 3; i++)
    {
        Texture[i].Destroy();
    }

    Preprocess.Destroy();
    DeferredLighting.Destroy();
    Antialiasing.Destroy();

    glDeleteBuffers(1, &VBO);

    glDeleteTextures(2, ColorBuffers);
    glDeleteTextures(1, &NormalBuffer);
    glDeleteTextures(1, &DepthBuffer);

    if(GLEW_EXT_framebuffer_object)
    {
        glDeleteFramebuffersEXT(1, &FBO);
    }
}

void COpenGLRenderer::InitArrayBuffers()
{
    CBuffer buffer;

    ...

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, buffer.GetDataSize(), buffer.GetData(), GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    buffer.Empty();
}

...

void COpenGLView::OnKeyDown(UINT Key)
{
    switch(Key)
    {
        case VK_F1:
            OpenGLRenderer.CalculateAntialiasing = !OpenGLRenderer.CalculateAntialiasing;
            break;

        ...
    }
}

...
antialiasing.vs
#version 120

void main()
{
    gl_TexCoord[0] = gl_Vertex;
    gl_Position = gl_Vertex * 2.0 - 1.0;
}
antialiasing.fs
#version 120

uniform sampler2D ColorBuffer, NormalBuffer, DepthBuffer;
uniform vec2 PixelSize;

vec2 Offsets[8] = vec2[](
    vec2(-1.0,  1.0),
    vec2( 0.0,  1.0),
    vec2( 1.0,  1.0),
    vec2( 1.0,  0.0),
    vec2( 1.0, -1.0),
    vec2( 0.0, -1.0),
    vec2(-1.0, -1.0),
    vec2(-1.0,  0.0)
);

void main()
{
    vec2 TexCoords[8];

    for(int i = 0; i < 8; i++)
    {  
        TexCoords[i] = gl_TexCoord[0].st + Offsets[i] * PixelSize;
    }

    float Depth = texture2D(DepthBuffer, gl_TexCoord[0].st).r;

    vec4 Depths1, Depths2;

    Depths1.x = texture2D(DepthBuffer, TexCoords[0]).r;
    Depths1.y = texture2D(DepthBuffer, TexCoords[1]).r;
    Depths1.z = texture2D(DepthBuffer, TexCoords[2]).r;
    Depths1.w = texture2D(DepthBuffer, TexCoords[3]).r;
    Depths2.x = texture2D(DepthBuffer, TexCoords[4]).r;
    Depths2.y = texture2D(DepthBuffer, TexCoords[5]).r;
    Depths2.z = texture2D(DepthBuffer, TexCoords[6]).r;
    Depths2.w = texture2D(DepthBuffer, TexCoords[7]).r;

    vec4 DepthDeltas1 = abs(Depths1 - Depth);
    vec4 DepthDeltas2 = abs(Depth - Depths2);

    vec4 MinDepthDeltas = max(min(DepthDeltas1, DepthDeltas2), 0.00001);
    vec4 MaxDepthDeltas = max(DepthDeltas1, DepthDeltas2);

    vec4 DepthResults = step(MinDepthDeltas * 25.0, MaxDepthDeltas);

    vec3 Normal = normalize(texture2D(NormalBuffer, gl_TexCoord[0].st).rgb * 2.0 - 1.0);

    vec4 Dots1, Dots2;

    Dots1.x = dot(normalize(texture2D(NormalBuffer, TexCoords[0]).rgb * 2.0 - 1.0), Normal);         
    Dots1.y = dot(normalize(texture2D(NormalBuffer, TexCoords[1]).rgb * 2.0 - 1.0), Normal);
    Dots1.z = dot(normalize(texture2D(NormalBuffer, TexCoords[2]).rgb * 2.0 - 1.0), Normal);
    Dots1.w = dot(normalize(texture2D(NormalBuffer, TexCoords[3]).rgb * 2.0 - 1.0), Normal);
    Dots2.x = dot(normalize(texture2D(NormalBuffer, TexCoords[4]).rgb * 2.0 - 1.0), Normal);
    Dots2.y = dot(normalize(texture2D(NormalBuffer, TexCoords[5]).rgb * 2.0 - 1.0), Normal);
    Dots2.z = dot(normalize(texture2D(NormalBuffer, TexCoords[6]).rgb * 2.0 - 1.0), Normal);
    Dots2.w = dot(normalize(texture2D(NormalBuffer, TexCoords[7]).rgb * 2.0 - 1.0), Normal);

    vec4 DotDeltas = abs(Dots1 - Dots2);

    vec4 NormalResults = step(0.4, DotDeltas);

    vec4 Results = max(NormalResults, DepthResults);

    float EdgeWeight = (Results.x + Results.y + Results.z + Results.w) * 0.25;

    if(EdgeWeight > 0.0)
    {
        vec3 Color = texture2D(ColorBuffer, gl_TexCoord[0].st).rgb;
        vec3 ColorsSum = vec3(0.0);

        for(int i = 0; i < 8; i++)
        {
            ColorsSum += texture2D(ColorBuffer, TexCoords[i]).rgb;
        }

        gl_FragColor = vec4(mix(Color, ColorsSum * 0.125, EdgeWeight), 1.0);
    }
    else
    {
        gl_FragColor = texture2D(ColorBuffer, gl_TexCoord[0].st);
    }
}
Download
deferred_rendering_antialiasing.zip (Visual Studio 2005 Professional)

© 2010 - 2016 Bc. Michal Belanec, michalbelanec@centrum.sk
Last update June 25, 2016
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