JOGL 阴影映射
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【中文标题】JOGL 阴影映射【英文标题】：JOGL shadow mapping 【发布时间】：2016-02-25 22:12:32 【问题描述】：我正在使用 JOGL 将 OpenGL SuperBible 演示翻译成 Java。直到第 12 章的所有演示都进行得很顺利，但现在我陷入了阴影映射。这是我的设置：
public class ShadowMap implements GLEventListener
public static void main(String[] args)
ShadowMap rend = new ShadowMap();
window.NEWTWindowStarter.init(rend, null, null);
private int light_program, camera_program;
private int[] obj, bkg;
private int camera_mv_pointer, camera_proj_pointer, light_mvp_pointer, camera_shadow_pointer;
private int fbo, depth_tex;
private int screen_width, screen_height;
private float aspect;
private double[] light_position, camera_position;
private double[][] light_proj_matrix, light_view_matrix;
private double[][] camera_proj_matrix, camera_view_matrix;
private double[][] bias_matrix, shadow_matrix;
private double[][] obj_model_matrix, bkg_model_matrix;
@Override
public void init(GLAutoDrawable glAutoDrawable)
GL4 gl = glAutoDrawable.getGL().getGL4bc();
ObjectParser parser = new ObjectParser("pawn_s.obj");
obj = BufferController.prepareVAO(gl, parser.getDataHolder());
parser = new ObjectParser("bkg.obj");
bkg = BufferController.prepareVAO(gl, parser.getDataHolder());
light_program = ShaderController.init(gl, "shaders/demo/d25/light_v.glsl", "shaders/demo/d25/light_f.glsl");
light_mvp_pointer = gl.glGetUniformLocation(light_program, "mvp");
camera_program = ShaderController.init(gl, "shaders/demo/d25/camera_v.glsl", "shaders/demo/d25/camera_f.glsl");
camera_mv_pointer = gl.glGetUniformLocation(camera_program, "mv_matrix");
camera_proj_pointer = gl.glGetUniformLocation(camera_program, "proj_matrix");
camera_shadow_pointer = gl.glGetUniformLocation(camera_program, "shadow_matrix");
depth_tex = BufferController.generateTextureId(gl);
gl.glBindTexture(gl.GL_TEXTURE_2D, depth_tex);
gl.glTexStorage2D(gl.GL_TEXTURE_2D, 11, gl.GL_DEPTH_COMPONENT32F, 1024, 1024);
gl.glTexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MIN_FILTER, gl.GL_LINEAR);
gl.glTexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MAG_FILTER, gl.GL_LINEAR);
gl.glTexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_WRAP_S, gl.GL_CLAMP_TO_BORDER);
gl.glTexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_WRAP_T, gl.GL_CLAMP_TO_BORDER);
gl.glTexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_COMPARE_MODE, gl.GL_COMPARE_REF_TO_TEXTURE);
gl.glTexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_COMPARE_FUNC, gl.GL_LEQUAL);
gl.glActiveTexture(gl.GL_TEXTURE0);
gl.glBindTexture(gl.GL_TEXTURE_2D, depth_tex);
fbo = BufferController.generateFrameId(gl);
gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, fbo);
gl.glFramebufferTexture(gl.GL_FRAMEBUFFER, gl.GL_DEPTH_ATTACHMENT, depth_tex, 0);
gl.glDrawBuffer(gl.GL_NONE);
gl.glReadBuffer(gl.GL_NONE);
if(gl.glCheckFramebufferStatus(gl.GL_FRAMEBUFFER) == gl.GL_FRAMEBUFFER_COMPLETE)
System.out.println("FrameBuffer OK!");
else
System.out.println("FrameBuffer FAIL!");
gl.glBindTexture(gl.GL_TEXTURE_2D, 0);
gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, 0);
gl.glEnable(gl.GL_DEPTH_TEST);
@Override
public void dispose(GLAutoDrawable glAutoDrawable)
@Override
public void display(GLAutoDrawable glAutoDrawable)
GL4bc gl = glAutoDrawable.getGL().getGL4bc();
computerMatrices();
gl.glEnable(gl.GL_DEPTH_TEST);
// depth pass
gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, fbo);
gl.glViewport(0, 0, 1024, 1024);
gl.glUseProgram(light_program);
drawFromLight(gl, obj, obj_model_matrix);
drawFromLight(gl, bkg, bkg_model_matrix);
gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, 0);
// final pass
gl.glViewport(0, 0, screen_width, screen_height);
gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT);
gl.glBindTexture(gl.GL_TEXTURE_2D, depth_tex);
gl.glDrawBuffer(gl.GL_BACK);
gl.glUseProgram(camera_program);
drawFromCamera(gl, obj, obj_model_matrix);
drawFromCamera(gl, bkg, bkg_model_matrix);
gl.glBindTexture(gl.GL_TEXTURE_2D, 0);
private void computerMatrices()
bkg_model_matrix = Matrix.model(0, 0, 0, 0, 0, 0, 1);
obj_model_matrix = Matrix.model(0, 0, 0, 0, 0, 0, 1);
light_position = new double[]10, 10, 10;
camera_position = new double[]10, 0, 10;
light_proj_matrix = Matrix.frustum(-1.0, 1.0, -1.0, 1.0, 1.0, 200.0);
light_view_matrix = Matrix.lookAt(light_position, new double[]0, 0, 0, new double[]0, 1, 0);
camera_proj_matrix = Matrix.perspective(60, aspect, 0.1f, 1000f);
camera_view_matrix = Matrix.lookAt(camera_position, new double[]0, 0, 0, new double[]0, 1, 0);
bias_matrix = new double[][]
0.5, 0.0, 0.0, 0.0,
0.0, 0.5, 0.0, 0.0,
0.0, 0.0, 0.5, 0.0,
0.5, 0.5, 0.5, 1.0;
shadow_matrix = Matrix.mult(bias_matrix, light_proj_matrix, light_view_matrix);
private void drawFromLight(GL4bc gl, int[] obj, double[][] model_matrix)
gl.glUniformMatrix4fv(light_mvp_pointer, 1, false, Matrix.toArrayF(Matrix.mult(light_proj_matrix, light_view_matrix, model_matrix)), 0);
BufferControllerDep.renderTrianglesVAO(gl, obj[0], obj[1], obj[2]);
private void drawFromCamera(GL4bc gl, int[] obj, double[][] model_matrix)
gl.glUniformMatrix4fv(camera_shadow_pointer, 1, false, Matrix.toArrayF(Matrix.mult(shadow_matrix, model_matrix)), 0);
gl.glUniformMatrix4fv(camera_proj_pointer, 1, false, Matrix.toArrayF(camera_proj_matrix), 0);
gl.glUniformMatrix4fv(camera_mv_pointer, 1, false, Matrix.toArrayF(Matrix.mult(camera_view_matrix, model_matrix)), 0);
BufferControllerDep.renderTrianglesVAO(gl, obj[0], obj[1], obj[2]);
@Override
public void reshape(GLAutoDrawable glAutoDrawable, int x, int y, int width, int height)
screen_width = width;
screen_height = height;
aspect = (1.0f * screen_width) / screen_height;
灯光着色器是非常基础的。 Camera Vertex shader如下：
#version 430 core
uniform mat4 mv_matrix;
uniform mat4 proj_matrix;
uniform mat4 shadow_matrix;
layout (location = 0) in vec4 position;
layout (location = 1) in vec3 normal;
out vec4 shadow_coord;
uniform vec3 light_pos = vec3(10.0, 10.0, 10.0);
out vec3 N;
out vec3 L;
void main(void)
N = normalize(mat3(mv_matrix) * normal);
L = normalize(light_pos - (mv_matrix * position).xyz);
shadow_coord = shadow_matrix * position;
gl_Position = proj_matrix * mv_matrix * position;
和相机片段着色器：
#version 430 core
layout (location = 0) out vec4 color;
layout (binding = 0) uniform sampler2DShadow shadow_tex;
in vec4 shadow_coord;
uniform vec3 D = vec3(0.9, 0.8, 1.0);
in vec3 N;
in vec3 L;
void main(void)
vec3 diffuse = dot(N, L) * D;
float shadow = textureProj(shadow_tex, shadow_coord);
// color = vec4(diffuse, 1.0);
color = shadow * vec4(1);
仅渲染漫反射效果很好。投影、LookAt 和转换矩阵似乎可以工作。
但是，当尝试渲染阴影时，它会失败：
将光线移近物体会产生这样的效果：
我使用自己的 Matrix 和 Vector 类，如果需要可以提供源代码。
感谢任何见解。谢谢！
【问题讨论】：
乍一看似乎还不错。无论如何，在最后一次传递中绑定纹理之前，我总是会调用gl.glActiveTexture(gl.GL_TEXTURE0);。我不知道this sample 是否有帮助。但是，您需要找到一种调试方法，打开调试输出并退回到更简单的形状，例如要阴影的单个三角形
感谢您的建议。我将问题追溯到反转矩阵多顺序。另外，我想运行你的演示，但我遇到了一个问题：运行你直接引用的演示会打开一个黑色窗口，但没有进行渲染（永远不会到达render(GL gl) 中的断点）。我做错了什么？
控制台打印有问题吗？无论如何，为找到问题而喝彩:)
什么都没有。我直接从 Gl_400_fbo_shadow 类启动它。我看到它在测试类中通过assert render(gl);，但它没有到达 Gl_400_fbo_shadow 中render(GL gl) 中的任何断点。我对所有演示都得到了相同的结果...
你会为此打开一个issue 吗？
【参考方案1】：
问题是由 Java 代码中的逆矩阵乘法顺序引起的。这是更正的代码：
private void drawFromLight(GL4bc gl, int[] obj, double[][] model_matrix)
gl.glUniformMatrix4fv(light_mvp_pointer, 1, false,
Matrix.toArrayF(Matrix.mult(model_matrix, light_view_matrix, light_proj_matrix)), 0);
BufferControllerDep.renderTrianglesVAO(gl, obj[0], obj[1], obj[2]);
private void drawFromCamera(GL4bc gl, int[] obj, double[][] model_matrix)
gl.glUniformMatrix4fv(camera_shadow_pointer, 1, false,
Matrix.toArrayF(Matrix.mult(model_matrix, shadow_matrix)), 0);
gl.glUniformMatrix4fv(camera_mv_pointer, 1, false,
Matrix.toArrayF(Matrix.mult(model_matrix, camera_view_matrix)), 0);
gl.glUniformMatrix4fv(camera_mvp_pointer, 1, false,
Matrix.toArrayF(Matrix.mult(model_matrix, camera_view_matrix, camera_proj_matrix)), 0);
BufferControllerDep.renderTrianglesVAO(gl, obj[0], obj[1], obj[2]);
使用相同的着色器将产生以下结果：
同时添加
gl.glEnable(gl.GL_POLYGON_OFFSET_FILL);
gl.glPolygonOffset(2.0f, 0.0f);
在执行“light pass”之前消除失真：
混合阴影和漫反射会产生这样的效果：
还有改进的余地...
【讨论】：
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