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我想從「用Java語言編寫OpenGL計算機圖形編程」一書中學習JOGL。所以我顯然沒有工作知識。我精確地遵循了這個例子，花了很多時間來診斷我做錯了什麼。我最終試圖運行從本書提供的代碼，甚至沒有工作。我以前已經能夠得到一個三角形顯示，但一個三維立方體仍然躲過我。下面是這本書的逐字代碼：沒有顯示錯誤，屏幕顯示黑色，JOGL
public class Code extends JFrame implements GLEventListener
{ private GLCanvas myCanvas;
private int rendering_program;
private int vao[] = new int[1];
private int vbo[] = new int[2];
private float cameraX, cameraY, cameraZ;
private float cubeLocX, cubeLocY, cubeLocZ;
private GLSLUtils util = new GLSLUtils();
public Code()
{ setTitle("Chapter4 - program1a");
setSize(600, 600);
myCanvas = new GLCanvas();
myCanvas.addGLEventListener(this);
getContentPane().add(myCanvas);
this.setVisible(true);
}
public void display(GLAutoDrawable drawable)
{ GL4 gl = (GL4) GLContext.getCurrentGL();
gl.glClear(GL_DEPTH_BUFFER_BIT);
gl.glUseProgram(rendering_program);
int mv_loc = gl.glGetUniformLocation(rendering_program, "mv_matrix");
int proj_loc = gl.glGetUniformLocation(rendering_program, "proj_matrix");
float aspect = (float) myCanvas.getWidth()/(float) myCanvas.getHeight();
Matrix3D pMat = perspective(60.0f, aspect, 0.1f, 1000.0f);
Matrix3D vMat = new Matrix3D();
vMat.translate(-cameraX, -cameraY, -cameraZ);
Matrix3D mMat = new Matrix3D();
mMat.translate(cubeLocX, cubeLocY, cubeLocZ);
Matrix3D mvMat = new Matrix3D();
mvMat.concatenate(vMat);
mvMat.concatenate(mMat);
gl.glUniformMatrix4fv(mv_loc, 1, false, mvMat.getFloatValues(), 0);
gl.glUniformMatrix4fv(proj_loc, 1, false, pMat.getFloatValues(), 0);
gl.glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
gl.glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
gl.glEnableVertexAttribArray(0);
gl.glEnable(GL_DEPTH_TEST);
gl.glDepthFunc(GL_LEQUAL);
gl.glDrawArrays(GL_TRIANGLES, 0, 36);
}
public void init(GLAutoDrawable drawable)
{ GL4 gl = (GL4) drawable.getGL();
rendering_program = createShaderProgram();
setupVertices();
cameraX = 0.0f; cameraY = 0.0f; cameraZ = 8.0f;
cubeLocX = 0.0f; cubeLocY = -2.0f; cubeLocZ = 0.0f;
}
private void setupVertices()
{ GL4 gl = (GL4) GLContext.getCurrentGL();
float[] vertex_positions =
{ -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f,
1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 1.0f, -1.0f,
1.0f, -1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, -1.0f,
1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f,
1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f,
1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f,
-1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f,
1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, -1.0f
};
gl.glGenVertexArrays(vao.length, vao, 0);
gl.glBindVertexArray(vao[0]);
gl.glGenBuffers(vbo.length, vbo, 0);
gl.glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
FloatBuffer vertBuf = Buffers.newDirectFloatBuffer(vertex_positions);
gl.glBufferData(GL_ARRAY_BUFFER, vertBuf.limit()*4, vertBuf, GL_STATIC_DRAW);
}
private Matrix3D perspective(float fovy, float aspect, float n, float f)
{ float q = 1.0f/((float) Math.tan(Math.toRadians(0.5f * fovy)));
float A = q/aspect;
float B = (n + f)/(n - f);
float C = (2.0f * n * f)/(n - f);
Matrix3D r = new Matrix3D();
r.setElementAt(0,0,A);
r.setElementAt(1,1,q);
r.setElementAt(2,2,B);
r.setElementAt(3,2,-1.0f);
r.setElementAt(2,3,C);
r.setElementAt(3,3,0.0f);
return r;
}
public static void main(String[] args) { new Code(); }
public void reshape(GLAutoDrawable drawable, int x, int y, int width, int height) {}
public void dispose(GLAutoDrawable drawable) {}
private int createShaderProgram()
{ GL4 gl = (GL4) GLContext.getCurrentGL();
String vshaderSource[] = readShaderSource("resources/vert.shader");
String fshaderSource[] = readShaderSource("resources/frag.shader");
int vShader = gl.glCreateShader(GL_VERTEX_SHADER);
int fShader = gl.glCreateShader(GL_FRAGMENT_SHADER);
gl.glShaderSource(vShader, vshaderSource.length, vshaderSource, null, 0);
gl.glShaderSource(fShader, fshaderSource.length, fshaderSource, null, 0);
gl.glCompileShader(vShader);
gl.glCompileShader(fShader);
int vfprogram = gl.glCreateProgram();
gl.glAttachShader(vfprogram, vShader);
gl.glAttachShader(vfprogram, fShader);
gl.glLinkProgram(vfprogram);
return vfprogram;
}
public String[] readShaderSource(String path) {
//reads in shader programs
ArrayList<String> builder = new ArrayList();
try (InputStream in = new FileInputStream(path);
BufferedReader reader = new BufferedReader(new InputStreamReader(in))) {
String line;
while ((line = reader.readLine()) != null) {
builder.add(line + "\n");
}
} catch (IOException ex) {
throw new RuntimeException("Failed to load a shader file!"
+ System.lineSeparator() + ex.getMessage());
}
return builder.toArray(new String[1]);
}
}
不是逐字添加我自己的文件加載器。
着色器：
#version 430
out vec4 color;
uniform mat4 mv_matrix;
uniform mat4 proj_matrix;
void main(void)
{ color = vec4(1.0, 0.0, 0.0, 1.0);
}
#version 430
layout (location=0) in vec3 position;
uniform mat4 mv_matrix;
uniform mat4 proj_matrix;
void main(void)
{
gl_Position = proj_matrix * mv_matrix * vec4(position,1.0);
}