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fix depth calculation and separate 3D texture size from model size
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also correctly compute normal in case the
ray immediately hits the model box.
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@httpdigest
httpdigest committed Jan 7, 2024
1 parent 69c3a86 commit fa3334b
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Showing 2 changed files with 37 additions and 20 deletions.
21 changes: 14 additions & 7 deletions res/org/lwjgl/demo/opengl/shader/raymarching.fs.glsl
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Original file line number Diff line number Diff line change
Expand Up @@ -11,25 +11,31 @@ layout (depth_less) out float gl_FragDepth;
#endif

uniform sampler3D tex;
uniform vec3 size;
uniform mat4 mvp;

in vec3 o;
in vec3 d;

vec3 rayMarch(vec3 o, vec3 d, vec3 ts) {
vec3 rayMarch(vec3 o, vec3 d, vec3 n, vec3 size) {
vec3 ts = vec3(textureSize(tex, 0));
float ti = 0.0;
vec3 p = floor(o), di = vec3(1.0) / d, s = sign(d), t = abs((p + max(s, vec3(0.0)) - o) * di);
int N = int(ts.x + ts.y + ts.z); // <- maximum can only be manhattan distance
int N = int(size.x + size.y + size.z); // <- maximum can only be manhattan distance
vec3 c;
int i;
for (i = 0; i < N; i++) {
if (texture(tex, (p+vec3(0.5))/ts).r > 0.0) {
vec4 cp = mvp * vec4((o+d*t)/ts-vec3(0.5), 1.0);
vec4 cp = mvp * vec4((o+d*ti)/size-vec3(0.5), 1.0);
gl_FragDepth = cp.z / cp.w;
return abs(c);
return n;
}
c = step(t.xyz, t.yzx)*step(t.xyz, t.zxy);
t += di * s * c;
p += s * c;
vec3 ds = s*c;
ti = min(t.x, min(t.y, t.z));
n = -ds;
t += di * ds;
p += ds;
if (any(lessThan(p, vec3(0.0))) || any(greaterThanEqual(p, ts))) {
break;
}
Expand All @@ -40,6 +46,7 @@ vec3 rayMarch(vec3 o, vec3 d, vec3 ts) {
void main(void) {
vec3 ts = vec3(textureSize(tex, 0));
vec3 di = 1.0/d, t = min((vec3(-0.5)-o)*di, (vec3(0.5)-o)*di);
vec3 s = sign(d), n = -s*step(t.yzx, t.xyz)*step(t.zxy, t.xyz);
vec3 p = o + d * max(max(max(t.x, t.y), t.z), 0.0);
fragColor = vec4(rayMarch((p+vec3(0.5))*ts, d*ts, ts), 1.0);
fragColor = vec4(rayMarch((p+vec3(0.5))*size, d*size, n, size), 1.0);
}
36 changes: 23 additions & 13 deletions src/org/lwjgl/demo/opengl/shader/RayMarchingVolumeTexture.java
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,6 @@

import org.joml.Matrix4f;
import org.joml.Vector3f;
import org.joml.Vector3i;
import org.lwjgl.BufferUtils;
import org.lwjgl.demo.util.MagicaVoxelLoader;
import org.lwjgl.glfw.*;
Expand All @@ -40,6 +39,7 @@ public class RayMarchingVolumeTexture {
private static class Volume {
int x, y, z;
int w, h, d;
int tw, th, td;
int tex;
byte[] field;
}
Expand All @@ -49,7 +49,7 @@ private static class Volume {
private int height = 768;

private int program;
private int mvpUniform, invModelUniform, camPositionUniform;
private int mvpUniform, invModelUniform, camPositionUniform, sizeUniform;

private GLFWErrorCallback errCallback;
private Callback debugProc;
Expand Down Expand Up @@ -155,7 +155,6 @@ else if (action == GLFW_RELEASE)
}
glfwMakeContextCurrent(window);
glfwSwapInterval(1);
glfwShowWindow(window);
GL.createCapabilities();
debugProc = GLUtil.setupDebugMessageCallback();
glClearColor(0.1f, 0.15f, 0.23f, 1.0f);
Expand All @@ -166,6 +165,7 @@ else if (action == GLFW_RELEASE)
volumes.add(create3dVolume("org/lwjgl/demo/models/mikelovesrobots_mmmm/scene_house5.vox", 0, 0, 0));
volumes.add(create3dVolume("org/lwjgl/demo/models/mikelovesrobots_mmmm/scene_house6.vox", 140, 0, 0));
createBoxVao();
glfwShowWindow(window);
}
private void createBoxVao() {
int vao = glGenVertexArrays();
Expand All @@ -188,22 +188,32 @@ private void createBoxVao() {
private static int idx(int x, int y, int z, int width, int height) {
return x + width * (y + z * height);
}
private static int nextPowerOfTwo(int v) {
v--;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
return (v | v >> 16) + 1;
}
private Volume create3dVolume(String resource, int x, int y, int z) throws IOException {
int texture = glGenTextures();
glBindTexture(GL_TEXTURE_3D, texture);
Vector3i dims = new Vector3i();
Volume v = new Volume();
v.x = x;
v.y = y;
v.z = z;
try (InputStream is = Objects.requireNonNull(getSystemResourceAsStream(resource))) {
BufferedInputStream bis = new BufferedInputStream(is);
new MagicaVoxelLoader().read(bis, new MagicaVoxelLoader.Callback() {
public void voxel(int x, int y, int z, byte c) {
v.field[idx(x, z, dims.z - 1 - y, dims.x, dims.y)] = c;
v.field[idx(x, z, v.td - 1 - y, v.tw, v.th)] = c;
}
public void size(int x, int y, int z) {
dims.x = x;
dims.y = z;
dims.z = y;
v.field = new byte[x * y * z];
v.tw = nextPowerOfTwo(x);
v.th = nextPowerOfTwo(z);
v.td = nextPowerOfTwo(y);
v.field = new byte[v.tw * v.th * v.td];
v.w = x;
v.h = z;
v.d = y;
Expand All @@ -216,16 +226,14 @@ public void paletteMaterial(int i, MagicaVoxelLoader.Material mat) {
bb.put(v.field);
bb.flip();
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexImage3D(GL_TEXTURE_3D, 0, GL_R8, v.w, v.h, v.d, 0, GL_RED, GL_UNSIGNED_BYTE, bb);
glTexImage3D(GL_TEXTURE_3D, 0, GL_R8, v.tw, v.th, v.td, 0, GL_RED, GL_UNSIGNED_BYTE, bb);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glGenerateMipmap(GL_TEXTURE_3D);
v.tex = texture;
v.x = x;
v.y = y;
v.z = z;
return v;
}
private void createProgram() throws IOException {
Expand All @@ -248,6 +256,7 @@ private void createProgram() throws IOException {
mvpUniform = glGetUniformLocation(program, "mvp");
invModelUniform = glGetUniformLocation(program, "invModel");
camPositionUniform = glGetUniformLocation(program, "camPosition");
sizeUniform = glGetUniformLocation(program, "size");
int texUniform = glGetUniformLocation(program, "tex");
glUniform1i(texUniform, 0);
glUseProgram(0);
Expand All @@ -259,6 +268,7 @@ private void renderVolume(Volume v) {
glUniformMatrix4fv(mvpUniform, false, mvpMatrix.get(matrixBuffer));
modelMatrix.invert(invModelMatrix);
glUniformMatrix4fv(invModelUniform, false, invModelMatrix.get(matrixBuffer));
glUniform3f(sizeUniform, v.w, v.h, v.d);
glDrawElements(GL_TRIANGLE_STRIP, 14, GL_UNSIGNED_SHORT, 0L);
}
private void loop() {
Expand Down

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