DemoBox.kt

import org.openrndr.WindowMultisample
import org.openrndr.application
import org.openrndr.color.ColorRGBa
import org.openrndr.draw.CullTestPass
import org.openrndr.draw.DrawPrimitive
import org.openrndr.draw.colorBuffer
import org.openrndr.draw.shadeStyle
import org.openrndr.extra.camera.Orbital
import org.openrndr.extra.meshgenerators.boxMesh
import org.openrndr.math.Vector3

/**
 * Demonstrates how to create a 3D mesh box by specifying its width, height and depth.
 *
 * The `box` is a `VertexBuffer` and contains texture coordinates which can be
 * used to apply a texture to its faces.
 *
 * After creating the box, the program creates a texture with a gradient.
 * In it, the red component increases along the x-axis and the green component
 * along the y-axis.
 *
 * The scene is rendered with an interactive `Orbital` 3D camera.
 *
 * A shade style is used to apply the texture to the box.
 *
 */
fun main() = application {
    configure {
        width = 720
        height = 720
        multisample = WindowMultisample.SampleCount(8)
    }
    program {
        val box = boxMesh(1.0, 1.0, 1.0)

        val texture = colorBuffer(256, 256)
        val s = texture.shadow
        for (y in 0 until 256) {
            for (x in 0 until 256) {
                s[x, y] = ColorRGBa(x / 256.0, y / 256.0, 0.0, 1.0)
            }
        }
        s.upload()

        extend(Orbital()) {
            eye = Vector3(1.0, 1.0, 1.0)
        }
        extend {
            drawer.clear(ColorRGBa.PINK)
            drawer.shadeStyle = shadeStyle {
                fragmentTransform = """
                        x_fill = texture(p_texture, va_texCoord0.xy);
                    """.trimIndent()
                parameter("texture", texture)
            }
            drawer.drawStyle.cullTestPass = CullTestPass.FRONT
            drawer.vertexBuffer(box, DrawPrimitive.TRIANGLES)
        }
    }
}