OpenGL只画出1个三角形

Question

我对这个opengl lwjgl的东西比较新，并且已经彻底检查了我的代码，但只绘制了一个三角形，尽管我放入了2个coords。为了证明我的观点，绘制了6个点与GL_POINTS。

Main.scala

import org.lwjgl._ 
import org.lwjgl.glfw.Callbacks._ 
import org.lwjgl.glfw.GLFW._ 
import org.lwjgl.opengl.GL11._ 
import org.lwjgl.system.MemoryUtil._ 

class Main { 

    import org.lwjgl.glfw.GLFWErrorCallback 
    import org.lwjgl.opengl.GL 

    private var window = 0L 

    def run(): Unit = { 
    System.out.println("Version: " + Version.getVersion + "!") 
    init() 
    run_loop() 
    glfwFreeCallbacks(window) 
    glfwDestroyWindow(window) 
    glfwTerminate() 
    glfwSetErrorCallback(null).free() 
    } 

    private def init() = { 

    GLFWErrorCallback.createPrint(System.err).set 

    if (!glfwInit) throw new IllegalStateException("Unable to initialize GLFW") 

    glfwDefaultWindowHints() 

    glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE) 

    glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE) 

    window = glfwCreateWindow(640, 480, "WINDOW", 0, 0) 
    if (window == NULL) throw new RuntimeException("Failed to create the GLFW window") 
    glfwMakeContextCurrent(window) 
    glfwSwapInterval(1) 
    glfwShowWindow(window) 
    } 

    def run_loop() { 

    GL.createCapabilities 

    glEnable(GL_TEXTURE_2D) 

val vertices: Array[Float] = Array(

    -0.5f, 0.5f, 0, //TOP LEFT 
    0.5f, 0.5f, 0, //TOP RIGHT 
    0.5f, -0.5f, 0, //BOTTOM RIGHT 

    -0.5f, 0.5f, 0, //BOTTOM RIGHT 
    -0.5f, -0.5f, 0,//BOTTOM LEFT 
    -0.5f, 0.5f, 0 //TOP LEFT 

) 

val model: Model = Model(vertices) 

while (!glfwWindowShouldClose(window)) { 
    glfwPollEvents() 

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) 

    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GL_TRUE) { glfwSetWindowShouldClose(window, true) } 

    model.render() 

    glfwSwapBuffers(window) 
} 
    } 
} 

object Main { 
    def main(args: Array[String]): Unit = { 
    val main: Main = new Main 
    main.run() 
    } 
} 

Model.scala

import java.nio.FloatBuffer 

import org.lwjgl.BufferUtils 
import org.lwjgl.opengl.GL11._ 
import org.lwjgl.opengl.GL15._ 

case class Model (vertices: Array[Float]){ 

    private val draw_count: Int = vertices.length/3 
    private val v_id: Int = glGenBuffers 

    val buffer: FloatBuffer = BufferUtils.createFloatBuffer(vertices.length) 
    buffer.put(vertices) 
    buffer.flip() 

    glBindBuffer(GL_ARRAY_BUFFER, v_id) 
    glBufferData(GL_ARRAY_BUFFER, buffer, GL_DYNAMIC_DRAW) 
    glBindBuffer(GL_ARRAY_BUFFER, 0) 

    def render(): Unit = { 

    glEnableClientState(GL_VERTEX_ARRAY) 
    glBindBuffer(GL_ARRAY_BUFFER, v_id) 
    glVertexPointer(3, GL_FLOAT, 0, 0) 
    glDrawArrays(GL_QUADS, 0, draw_count) 
    glDrawArrays(GL_POINTS, 0, draw_count) 
    glBindBuffer(GL_ARRAY_BUFFER, 0) 
    glDisableClientState(GL_VERTEX_ARRAY) 
    glPopMatrix() 

    } 

} 

My Screenshot

Answer 1

你vertices是不正确的。如果0.5f, -0.5f是右下角，那么-0.5f, 0.5f怎么能也是右下角？

val vertices: Array[Float] = Array(
    -0.5f, 0.5f, 0, // TOP LEFT 
    0.5f, 0.5f, 0, // TOP RIGHT 
    0.5f, -0.5f, 0, // BOTTOM RIGHT 

    0.5f, -0.5f, 0, // BOTTOM RIGHT 
    -0.5f, -0.5f, 0, // BOTTOM LEFT 
    -0.5f, 0.5f, 0 // TOP LEFT 
) 

你也可以使用GL_TRIANGLE_STRIP连同：

val vertices: Array[Float] = Array(
    -0.5f, 0.5f, 0, // TOP LEFT 
    0.5f, 0.5f, 0, // TOP RIGHT 
    -0.5f, -0.5f, 0, // BOTTOM LEFT 
    0.5f, -0.5f, 0, // BOTTOM RIGHT 
) 

或翻转最后两个顶点，同样使用GL_TRIANGLE_FAN。

另请注意，每个glPushMatrix()必须有一个glPopMatrix()。由于我注意到你有一个glPopMatrix()但没有glPushMatrix()。