From cd4f2dce3994bee30faae3e3af88ab489fc7959c Mon Sep 17 00:00:00 2001
From: Joakim Kilby <jockekilby@gmail.com>
Date: Tue, 17 Oct 2023 10:11:42 +0200
Subject: [PATCH] support multiple shadowers (up to 10)

---
 .../shaders/globalrenderer_vs.glsl            |  3 ++-
 .../shaders/localrenderer_vs.glsl             |  9 +++++---
 .../globebrowsing/shaders/renderer_fs.glsl    | 21 ++++++++++++-------
 modules/globebrowsing/src/renderableglobe.cpp | 18 ++++++++++------
 4 files changed, 34 insertions(+), 17 deletions(-)

diff --git a/modules/globebrowsing/shaders/globalrenderer_vs.glsl b/modules/globebrowsing/shaders/globalrenderer_vs.glsl
index f1aed26245..3a932024aa 100644
--- a/modules/globebrowsing/shaders/globalrenderer_vs.glsl
+++ b/modules/globebrowsing/shaders/globalrenderer_vs.glsl
@@ -100,7 +100,8 @@ vec3 getLevelWeights(float distToVertexOnEllipsoid) {
   );
 }
 
-out vec4 position_lightspace;
+const int n_depthmaps = 10;
+out vec4 positions_lightspace[n_depthmaps];
 
 void main() {
   PositionNormalPair pair = globalInterpolation(in_uv);
diff --git a/modules/globebrowsing/shaders/localrenderer_vs.glsl b/modules/globebrowsing/shaders/localrenderer_vs.glsl
index 4898c8eb81..b9bbc4ca7c 100644
--- a/modules/globebrowsing/shaders/localrenderer_vs.glsl
+++ b/modules/globebrowsing/shaders/localrenderer_vs.glsl
@@ -67,9 +67,10 @@ uniform float chunkMinHeight;
 uniform float distanceScaleFactor;
 uniform int chunkLevel;
 
+const int n_depthmaps = 10;
 uniform dmat4 inv_vp;
-uniform dmat4 light_vp;
-out vec4 position_lightspace;
+uniform dmat4 light_vps[n_depthmaps];
+out vec4 positions_lightspace[n_depthmaps];
 
 
 vec3 bilinearInterpolation(vec2 uv) {
@@ -131,5 +132,7 @@ void main() {
   shadowCoords = vec4(shadowMatrix * dvec4(p, 1.0));
 #endif // SHADOW_MAPPING_ENABLED
 
-  position_lightspace = vec4(light_vp * (inv_vp * dvec4(p, 1.0)));
+  for (int idx = 0; idx < n_depthmaps; ++idx) {
+    positions_lightspace[idx] = vec4(light_vps[idx] * (inv_vp * dvec4(p, 1.0)));
+  }
 }
diff --git a/modules/globebrowsing/shaders/renderer_fs.glsl b/modules/globebrowsing/shaders/renderer_fs.glsl
index a944fc69fa..7b7882bde3 100644
--- a/modules/globebrowsing/shaders/renderer_fs.glsl
+++ b/modules/globebrowsing/shaders/renderer_fs.glsl
@@ -154,8 +154,9 @@ in vec3 positionWorldSpace;
 
 uniform float opacity;
 
-in vec4 position_lightspace;
-uniform sampler2D light_depth_map;
+const int n_depthmaps = 10;
+in vec4 positions_lightspace[n_depthmaps];
+uniform sampler2D light_depth_maps[n_depthmaps];
 
 Fragment getFragment() {
   Fragment frag;
@@ -294,12 +295,18 @@ Fragment getFragment() {
   frag.color.xyz *= shadow < 0.99 ? clamp(shadow + 0.3, 0.0, 1.0) : shadow;
 #endif
 
-  vec3 coords = position_lightspace.xyz / position_lightspace.w;
-  coords = coords * 0.5 + 0.5;
-  float sampled_depth = texture(light_depth_map, coords.xy).r;
-  float current_depth = coords.z;
+  bool shadowed = false;
+  for (int idx = 0; idx < n_depthmaps; ++idx) {
+    vec3 coords = positions_lightspace[idx].xyz / positions_lightspace[idx].w;
+    coords = coords * 0.5 + 0.5;
+    float sampled_depth = texture(light_depth_maps[idx], coords.xy).r;
+    float current_depth = coords.z;
+    if (current_depth > sampled_depth) {
+      shadowed = true;
+    }
+  }
 
-  if (current_depth > sampled_depth) {
+  if (shadowed) {
     frag.color.xyz *= 0.1;
   }
 
diff --git a/modules/globebrowsing/src/renderableglobe.cpp b/modules/globebrowsing/src/renderableglobe.cpp
index 6d727fe2c6..6306f61414 100644
--- a/modules/globebrowsing/src/renderableglobe.cpp
+++ b/modules/globebrowsing/src/renderableglobe.cpp
@@ -1643,16 +1643,22 @@ void RenderableGlobe::renderChunkLocally(const Chunk& chunk, const RenderData& d
         program.setUniform("shadowMapTexture", shadowMapUnit);
     }
 
-    if (depthMapData.size() > 0) {
-        _localRenderer.program->setUniform("light_vp", depthMapData[0].viewProjecion);
-        _localRenderer.program->setUniform("inv_vp", glm::inverse(data.camera.combinedViewMatrix()));
 
-        ghoul::opengl::TextureUnit depthmapUnit;
-        depthmapUnit.activate();
+    std::vector<glm::dmat4> light_vps;
+    std::vector<GLint> depthmaps;
+    for (const RenderableModel::DepthMapData& data : depthMapData) {
+        light_vps.push_back(data.viewProjecion);
+        ghoul::opengl::TextureUnit unit;
+        depthmaps.push_back(unit);
+        unit.activate();
         glBindTexture(GL_TEXTURE_2D, depthMapData[0].depthMap);
-        _localRenderer.program->setUniform("light_depth_map", depthmapUnit);
     }
 
+    _localRenderer.program->setUniform("inv_vp", glm::inverse(data.camera.combinedViewMatrix()));
+    _localRenderer.program->setUniform("light_depth_maps", depthmaps);
+    GLint loc = glGetUniformLocation(*_localRenderer.program, "light_vps");
+    glUniformMatrix4dv(loc, light_vps.size(), GL_FALSE, glm::value_ptr(light_vps.front()));
+
     glEnable(GL_DEPTH_TEST);
     if (!renderGeomOnly) {
         glEnable(GL_CULL_FACE);