NoopMathKt

NoopMathKt is a bare bones linear algebra Kotlin library with emphasis on integration with OpenGL.

Specifics

NoopMathKt stores matrices column-major. So, for a Mat4, the first 4 elements make up the first column of the matrix. For a Mat4, elements at index 0, 4, 8, and 12 make up the first row of the matrix. Vectors are treated as column vectors. This decision is strictly to maintain the standard conventions of mathematics and OpenGL itself.

NoopMathKt is agnostic to left-hand/right-hand. It's just a linear algebra number cruncher. Multiply two matrices and it will do matrix multiplication. As simple as that.

Use

Gradle

// build.gradle.kts

repositories {
    ...
    mavenCentral()
    maven("https://jitpack.io")
    ...
}

dependencies {
    ...
    implementation("com.github.lucodivo:NoopMathKt:v0.2.4-alpha") // or latest
    ...
}

Create a Camera Matrix

val translationMat = Mat4(
    1.0f, 0.0f, 0.0f, 0.0f,
    0.0f, 1.0f, 0.0f, 0.0f,
    0.0f, 0.0f, 1.0f, 0.0f,
    -position.x, -position.y, -position.z, 1.0f)

val measureMat = Mat4(
    xAxis.x, yAxis.x, zAxis.x, 0.0f,
    xAxis.y, yAxis.y, zAxis.y, 0.0f,
    xAxis.z, yAxis.z, zAxis.z, 0.0f,
    0.0f, 0.0f, 0.0f, 1.0f)

// Matrices should be read from right to left
// translate object, so that the camera lies at the origin
// measure the position of the object in the direction the camera is facing
val camerasMat = measureMat * translationMat

Uniform Helper Functions

fun setUniform(name: String, value: Vec2) = glUniform2fv(glGetUniformLocation(id, name), 1, value.elements, 0)
fun setUniform(name: String, value: Vec3) = glUniform3fv(glGetUniformLocation(id, name), 1, value.elements, 0)
fun setUniform(name: String, value: Vec4) = glUniform4fv(glGetUniformLocation(id, name), 1, value.elements, 0)

fun setUniform(name: String, value: Mat2) = glUniformMatrix2fv(glGetUniformLocation(id, name), 1, false, value.elements, 0)
fun setUniform(name: String, value: Mat3) = glUniformMatrix3fv(glGetUniformLocation(id, name), 1, false, value.elements, 0)
fun setUniform(name: String, value: Mat4) = glUniformMatrix4fv(glGetUniformLocation(id, name), 1, false, value.elements, 0)