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OpenGL projection matrix/view matrix/model matrix

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OpenGL projection matrix/view matrix/model matrix
« on: November 10, 2020, 23:50:37 »
Since there are few tutorials for OpenGL in java I followed this tutorial in c++ and make some adaptations: http://www.opengl-tutorial.org/beginners-tutorials/tutorial-2-the-first-triangle/
I successfully loaded shaders like that:
Code: [Select]
package me.mikey.engine;

import java.io.File;
import java.io.FileNotFoundException;
import java.nio.IntBuffer;
import java.util.Scanner;

import org.lwjgl.BufferUtils;
import org.lwjgl.PointerBuffer;


import static org.lwjgl.opengl.GL.*;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.opengl.GL15.*;
import static org.lwjgl.opengl.GL20.*;
import static org.lwjgl.opengl.GL30.*;




public class loadShader {
int LoadShaders(String vertex_file_path, String fragment_file_path) throws FileNotFoundException{

// Create the shaders
int VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
int FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);

// Read the Vertex Shader code from the file
String VertexShaderCode;
File fileVertex = new File(vertex_file_path);
Scanner scVertex = new Scanner(fileVertex);
 
   

scVertex.useDelimiter("\\Z");
VertexShaderCode = scVertex.next();

// Read the Fragment Shader code from the file
String FragmentShaderCode;
File fileFragment = new File(fragment_file_path);
Scanner scFragment = new Scanner(fileFragment);
 
   

scFragment.useDelimiter("\\Z");
FragmentShaderCode = scFragment.next();

int Result = GL_FALSE;
int InfoLogLength = 0;

// Compile Vertex Shader
System.out.println("Compiling shader: " + vertex_file_path);

glShaderSource(VertexShaderID, VertexShaderCode);
glCompileShader(VertexShaderID);
IntBuffer ResultBuffer = BufferUtils.createIntBuffer(1);
IntBuffer InfoLogLengthBuffer = BufferUtils.createIntBuffer(1);
// Check Vertex Shader
glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, ResultBuffer);
glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, InfoLogLengthBuffer);


// Compile Fragment Shader

System.out.println("Compiling shader: " + fragment_file_path);

glShaderSource(FragmentShaderID, FragmentShaderCode);
glCompileShader(FragmentShaderID);

// Check Fragment Shader
glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, ResultBuffer);
glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, InfoLogLengthBuffer);


// Link the program
System.out.println("Linking program");
int ProgramID = glCreateProgram();
glAttachShader(ProgramID, VertexShaderID);
glAttachShader(ProgramID, FragmentShaderID);
glLinkProgram(ProgramID);

// Check the program
glGetProgramiv(ProgramID, GL_LINK_STATUS, ResultBuffer);
glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, InfoLogLengthBuffer);


glDetachShader(ProgramID, VertexShaderID);
glDetachShader(ProgramID, FragmentShaderID);

glDeleteShader(VertexShaderID);
glDeleteShader(FragmentShaderID);

return ProgramID;
}
}

Maybe not the most pretty way, however it works I have a blue triangle. Now I want to add space into my 3d renderer. The third tutorial is about matrices, but they use a c++ library called glm which I guess it stands for graphics library math or something. I researched and found that lwjgl used to have a solution for matrices in version 2, but now we need to find another way. I found JOML, but I don't want to download it from some reasons that I can't specify. I decided to make my own matrices and vector classes. I used a class with 4 floats for vec4 and a class with 4x4 2d array for matrices. I added the operations(mat4x4 * mat4x4, mat4x4*vec4, vec4 + vec*, and the translate and scale of a matrix using a vec3) I can't figure out how to make the rotation matrix, the projection matrix and the view matrix. I know that the following code is very very messy, full of garbage, please don't judge me for that. I never created a library before and I don't know exactly how static, final and all of these modifiers work:
Code: [Select]
package math;

public class mat4 {
public float[][] mat = new float[4][4];


public vec4 multiplyWithVec(vec4 vector) {
vec4 result = new vec4(0f, 0f, 0f, 0f);

result.x = this.mat[0][0] * vector.x + this.mat[0][1] * vector.y + this.mat[0][2] * vector.z + this.mat[0][3] * vector.w;
result.y = this.mat[1][0] * vector.x + this.mat[1][1] * vector.y + this.mat[1][2] * vector.z + this.mat[1][3] * vector.w;
result.z = this.mat[2][0] * vector.x + this.mat[2][1] * vector.y + this.mat[2][2] * vector.z + this.mat[2][3] * vector.w;
result.w = this.mat[3][0] * vector.x + this.mat[3][1] * vector.y + this.mat[3][2] * vector.z + this.mat[3][3] * vector.w;
return result;

}
public mat4 multiplyWithMat(mat4 mat4x4) {
mat4 result = new mat4();
for(int n = 0;n<4;n++) {
for(int i = 0;i<4;i++) {
for(int j = 0;j<4;j++) {
result.mat[i][n] += this.mat[i][j] * mat4x4.mat[j][n];
}
}
}
return result;

}
public void translate(vec3 vector) {

this.mat[0][0] = 1;
this.mat[1][1] = 1;
this.mat[2][2] = 1;
this.mat[0][3] = vector.x;
this.mat[1][3] = vector.y;
this.mat[2][3] = vector.z;
this.mat[3][3] = 1;




}
public mat4 scale(vec3 scale) {
mat4 result = new mat4();
result.mat[0][0] = scale.x;
result.mat[1][1] = scale.y;
result.mat[2][2] = scale.z;
result.mat[3][3] = 1;

return result;
}



}

Code: [Select]
package math;

public class vec3 {
public float x, y, z;
public vec3(float x, float y, float z) {
this.x = x;
this.y = y;
this.z = z;

}
}
Code: [Select]
package math;

public class vec4 {
public float x, y, z, w;
public vec4(float x, float y, float z, float w) {
this.x = x;
this.y = y;
this.z = z;
this.w = w;
}


}