Category Archives: Modern OpenGL

Modern OpenGL

Texture Animation

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Texture Animation
5974008442.zip
// init 중간생략..

 for (int i=0; i<7; i++)
 {
  char filename[255];
  sprintf(filename, “tacgun0%d.rgb”, i);
        texture[i] = InitTexture(filename);
 }


// draw 중간생략..

 glActiveTexture(GL_TEXTURE0);
 glBindTexture(GL_TEXTURE_2D, texture[currentTex]);
 drawSquare();
 glBindTexture(GL_TEXTURE_2D, 0);

// update

void update()
{
 static int currentTime, deltaTime, prevTime = 0;
 currentTime = glutGet(GLUT_ELAPSED_TIME);
 deltaTime = currentTime – prevTime;
 prevTime = currentTime;
 currentTex = (GLuint) ((float)currentTime * 0.01) % 7;
 glutPostRedisplay();
}

Modern OpenGL

ModernOpenGL Mipmap

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Automatic mipmap generation


Mipmaps of a texture can be automatically generated with the glGenerateMipmap​ function. OpenGL 3.0 or greater is required for this function (or the extension GL_ARB_framebuffer_object). The function works quite simply; when you call it for a texture, mipmaps are generated for that texture:
http://www.opengl.org/wiki/Common_Mistakes#Automatic_mipmap_generation




  glTexImage2D(GL_TEXTURE_2D, 0, numComponents == 3 ? GL_RGB : GL_RGBA, imageWidth, imageHeight,  0, numComponents == 3 ? GL_RGB : GL_RGBA, GL_UNSIGNED_BYTE, imagePtr);
  glGenerateMipmap(GL_TEXTURE_2D); // Generate mipmaps now!!
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 4);



 

Modern OpenGL

OpenGL Texture Mapping Filtering & Environment Parameters

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Wrapping parameters (CLAMP | CLAMP_TO_EDGE | GL_REPEAT | GL_MIRRORED_REPEAT)


// Square Vertices Texture Coordinates
 squareTextureCoords.push_back(glm::vec2(-1.0f, -1.0f));
 squareTextureCoords.push_back(glm::vec2(3.0f, -1.0f));
 squareTextureCoords.push_back(glm::vec2(3.0f, 3.0f));
 squareTextureCoords.push_back(glm::vec2(-1.0f, 3.0f));

//(왼쪽 아래)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

//(오른쪽 아래)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

//(왼쪽 위)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

//(오른쪽 위)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT);
사용자 삽입 이미지4500481641.cpp

Magnification/Minification/Mipmap filter parameters (NEAREST | LINEAR)

//(위왼쪽)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);

//(위오른쪽)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

//(아래왼쪽)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

//(아래오른쪽)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
사용자 삽입 이미지3006233632.cpp

Modern OpenGL

TextureSquare

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//—-textureSquare.cpp
// 중간생략…
GLuint SetSquareData()
{
 // Vertice Positions
 squareVertices.push_back(glm::vec3(-0.75f, -0.75f, 0.0f));
 squareVertices.push_back(glm::vec3(0.75f, -0.75f, 0.0f));
 squareVertices.push_back(glm::vec3(0.75f, 0.75f, 0.0f));
 squareVertices.push_back(glm::vec3(-0.75f, 0.75f, 0.0f));
 // Vertices Textures
 squareTextureCoords.push_back(glm::vec2(0.0f, 0.0f));
 squareTextureCoords.push_back(glm::vec2(1.0f, 0.0f));
 squareTextureCoords.push_back(glm::vec2(1.0f, 1.0f));
 squareTextureCoords.push_back(glm::vec2(0.0f, 1.0f));
 // Vertice Indices
 squareIndices.push_back(0);
 squareIndices.push_back(1);
 squareIndices.push_back(2);
 squareIndices.push_back(0);
 squareIndices.push_back(2);
 squareIndices.push_back(3);


 // VAO
 GLuint vao;
 glGenVertexArrays(1, &vao);
 glBindVertexArray(vao);


 // VBO
 GLuint vbo[2];
 glGenBuffers(2, &vbo[0]);
 glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
 glBufferData(GL_ARRAY_BUFFER, 4*sizeof(glm::vec3), &squareVertices[0], GL_STATIC_DRAW);
 glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
 glEnableVertexAttribArray(0);
 glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
 glBufferData(GL_ARRAY_BUFFER, 4*sizeof(glm::vec2), &squareTextureCoords[0], GL_STATIC_DRAW);
 glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, 0);
 glEnableVertexAttribArray(1);


 // IBO
 GLuint ibo;
 glGenBuffers(1, &ibo);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6*sizeof(int), &squareIndices[0], GL_STATIC_DRAW);


 squareVertices.clear();
 squareTextureCoords.clear();


 return vao;
}




//————-TransformVertexShader.vert
#version 330


// Input vertex data
layout (location = 0) in vec3 vPosition; // vertex position (in model space)
layout (location = 1) in vec2 vTexCoord; // texture coordinate (in model space)


// Output data will be interpolated for each fragment.
out vec2 TexCoordPass;


// Values that stay constant for the whole mesh.
uniform mat4 gMVP;


void main()
{
 // Output position of the vertex, in clip space : gMVP * position
 gl_Position =  gMVP * vec4(vPosition,1);


 TexCoordPass = vTexCoord;
}




//———-TextureFragmentShader.frag
#version 330


// Interpolated values from the vertex shaders
in vec2 TexCoordPass;


// Ouput data
out vec4 Color;


// Values that stay constant for the whole mesh.
uniform sampler2D gTextureSampler;


void main()
{
 // Output color = color of the texture at the specified UV
 Color = texture2D(gTextureSampler, TexCoordPass);
}


사용자 삽입 이미지8018458209.frag