From 6c607dcb015ae0cf0f9f274622344b869e3af140 Mon Sep 17 00:00:00 2001
From: Jakob <jakob.g.maier@gmail.com>
Date: Wed, 11 Oct 2023 10:45:34 +0200
Subject: [PATCH] Fixed ParticleSystem depth testing, needs log depth value

---
 OpenGL_Flightsim/shaders/mesh.frag     | 10 ++++++++--
 OpenGL_Flightsim/shaders/particle.frag | 14 +++++++++++++-
 OpenGL_Flightsim/shaders/particle.vert |  4 +++-
 OpenGL_Flightsim/shaders/terrain.frag  |  9 ++++-----
 OpenGL_Flightsim/src/gfx/particles.cpp | 13 +++++++------
 5 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/OpenGL_Flightsim/shaders/mesh.frag b/OpenGL_Flightsim/shaders/mesh.frag
index 5f19aba..4b634d1 100644
--- a/OpenGL_Flightsim/shaders/mesh.frag
+++ b/OpenGL_Flightsim/shaders/mesh.frag
@@ -91,9 +91,11 @@ void main() {
     return;
   }
 
-  float farPlane = 150000.0;
-  float coeff = 2.0 / (log2(farPlane + 1.0) / 0.693);
+#if 1
+  float far = 150000.0;
+  float coeff = 2.0 / (log2(far + 1.0) / 0.693);
   gl_FragDepth = log2(FragDepth) * coeff * 0.5;
+#endif
 
   vec3 texColor = texture(u_Texture_01, TexCoords).rgb;
   vec3 reflectedColor = texture(u_EnvMap, ReflectedVector).rgb;
@@ -101,4 +103,8 @@ void main() {
   vec3 color = phongLighting(mix(texColor, reflectedColor, u_Shininess), u_LightDir, u_LightColor);
 
   gl_FragColor = vec4(color, u_Opacity);
+
+
+	//gl_FragColor = vec4(vec3(gl_FragCoord.z), 1.0);
+
 }
\ No newline at end of file
diff --git a/OpenGL_Flightsim/shaders/particle.frag b/OpenGL_Flightsim/shaders/particle.frag
index d5e2310..2ab6f74 100644
--- a/OpenGL_Flightsim/shaders/particle.frag
+++ b/OpenGL_Flightsim/shaders/particle.frag
@@ -5,9 +5,21 @@ out vec4 FragColor;
 
 in vec2 TexCoords;
 in vec4 Color;
+in float FragDepth;
 
 void main()
 {
-	//FragColor = texture(u_Texture, TexCoords) * vec4(u_Color, 1.0f);
+#if 0
+	FragColor = texture(u_Texture, TexCoords) * Color;
+ #else
 	FragColor = Color;
+#endif
+
+#if 1
+  // log depth buffer
+  float far = 150000.0;
+  float coeff = 2.0 / (log2(far + 1.0) / 0.693);
+  gl_FragDepth = log2(FragDepth) * coeff * 0.5;
+#endif
+
 }
\ No newline at end of file
diff --git a/OpenGL_Flightsim/shaders/particle.vert b/OpenGL_Flightsim/shaders/particle.vert
index fae28b5..becc46f 100644
--- a/OpenGL_Flightsim/shaders/particle.vert
+++ b/OpenGL_Flightsim/shaders/particle.vert
@@ -12,10 +12,10 @@ uniform vec3 u_Right;
 
 out vec2 TexCoords;
 out vec4 Color;
+out float FragDepth;
 
 void main()
 {
-
 	vec3 WorldPos = a_WorldPosAndSize.xyz;
 	float particleSize = a_WorldPosAndSize.w;
 
@@ -25,6 +25,8 @@ void main()
 
 	gl_Position = u_Projection * u_View * vec4(vertexPos, 1.0);
 
+  FragDepth = 1.0 + gl_Position.w;
+
 	TexCoords = a_VertexPos.xy + vec2(0.5, 0.5);
 	Color = a_Color;
 }
\ No newline at end of file
diff --git a/OpenGL_Flightsim/shaders/terrain.frag b/OpenGL_Flightsim/shaders/terrain.frag
index 75e7b9e..97f6401 100644
--- a/OpenGL_Flightsim/shaders/terrain.frag
+++ b/OpenGL_Flightsim/shaders/terrain.frag
@@ -90,7 +90,6 @@ void main()
 
   //vec4 terrainColor = vec4(calculateDirLight(lightDir, Normal, texture(u_Texture_01, TexCoord).rgb), 1.0);
 
-
   vec3 LightDir = vec3(0,1,0);
   vec3 LightColor = vec3(1.0);
   
@@ -103,9 +102,9 @@ void main()
   FragColor = mix(vec4(Color, 1.0), terrainColor, 0.5);
 #endif
 
-  float farPlane = 150000.0;
-  float coeff = 2.0 / (log2(farPlane + 1.0) / 0.693);
+#if 1
+  float far = 150000.0;
+  float coeff = 2.0 / (log2(far + 1.0) / 0.693);
   gl_FragDepth = log2(FragDepth) * coeff * 0.5;
-
-  //FragColor = terrainColor;
+#endif
 }
diff --git a/OpenGL_Flightsim/src/gfx/particles.cpp b/OpenGL_Flightsim/src/gfx/particles.cpp
index 6142dc9..0bfaf7c 100644
--- a/OpenGL_Flightsim/src/gfx/particles.cpp
+++ b/OpenGL_Flightsim/src/gfx/particles.cpp
@@ -138,10 +138,9 @@ void ParticleSystem::draw_self(RenderContext& context)
 
   // m_texture->bind(5);
 
-  // glEnable(GL_BLEND);
-  // glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
-  glDisable(GL_DEPTH_TEST);
-  glDepthMask(GL_FALSE);
+  glEnable(GL_BLEND);
+  //glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+  //glDepthMask(GL_TRUE);
 
   shader->bind();
   shader->set_uniform("u_View", view);
@@ -179,8 +178,10 @@ void ParticleSystem::draw_self(RenderContext& context)
   m_vao.unbind();
   shader->unbind();
 
-  glEnable(GL_DEPTH_TEST);
-  glDepthMask(GL_TRUE);
+
+  //glDepthMask(GL_TRUE);
+  //glDisable(GL_BLEND);
+
 }
 
 }  // namespace gfx