From 025f442686f5b5f6999e9b749801956010406e08 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackmchristensen.com>
Date: Sat, 17 Aug 2024 19:05:05 -0400
Subject: [PATCH] Add slider for tessellation factor

---
 imgui.ini                      | 10 +++++-----
 shaders/tessellation_ctrl.glsl |  2 +-
 source/scene.cpp               |  7 +++++++
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/imgui.ini b/imgui.ini
index 34d592c..4146e1a 100644
--- a/imgui.ini
+++ b/imgui.ini
@@ -4,8 +4,8 @@ Size=400,400
 Collapsed=0
 
 [Window][Terrain Controls]
-Pos=933,19
-Size=347,701
+Pos=856,19
+Size=424,701
 Collapsed=0
 DockId=0x00000002,0
 
@@ -24,12 +24,12 @@ Collapsed=0
 
 [Window][Scene Window]
 Pos=0,19
-Size=931,701
+Size=854,701
 Collapsed=0
 DockId=0x00000001,0
 
 [Docking][Data]
 DockSpace   ID=0x6F42A598 Window=0xE80F322C Pos=0,19 Size=1280,701 Split=X Selected=0x9F2D9299
-  DockNode  ID=0x00000001 Parent=0x6F42A598 SizeRef=931,701 CentralNode=1 Selected=0x9F2D9299
-  DockNode  ID=0x00000002 Parent=0x6F42A598 SizeRef=347,701 Selected=0xF69494A7
+  DockNode  ID=0x00000001 Parent=0x6F42A598 SizeRef=854,701 CentralNode=1 Selected=0x9F2D9299
+  DockNode  ID=0x00000002 Parent=0x6F42A598 SizeRef=424,701 Selected=0xF69494A7
 
diff --git a/shaders/tessellation_ctrl.glsl b/shaders/tessellation_ctrl.glsl
index 9401092..7539dd8 100644
--- a/shaders/tessellation_ctrl.glsl
+++ b/shaders/tessellation_ctrl.glsl
@@ -12,7 +12,7 @@ out TC_OUT {
     vec2 texCoord;
 } tc_out[];
 
-uniform float tessellationFactor = 64.0f;
+uniform float tessellationFactor;
 
 void main() {
     // Pass through position and texture coordinates to the tessellation evaluation shader
diff --git a/source/scene.cpp b/source/scene.cpp
index 1bb6a15..93ce056 100644
--- a/source/scene.cpp
+++ b/source/scene.cpp
@@ -39,6 +39,8 @@ const std::string kHGTPath = "hgt/N02E016.hgt";
 
 GLuint tex_id = -1;
 
+float tessellationFactor = 1.0f;
+
 std::vector<Vertex> vertices;
 std::vector<GLuint> indices;
 
@@ -222,6 +224,9 @@ void Scene::Display(GLFWwindow* window) {
     GLint heightTextureLoc = glGetUniformLocation(shader_program_, "heightTexture");
     glUniform1i(heightTextureLoc, 0);
 
+    GLint tessFactorLoc = glGetUniformLocation(shader_program_, "tessellationFactor");
+    glUniform1f(tessFactorLoc, tessellationFactor);
+
     glBindVertexArray(vao_);
     glPatchParameteri(GL_PATCH_VERTICES, 4);
     glDrawElements(GL_PATCHES, indices.size(), GL_UNSIGNED_INT, 0);
@@ -308,6 +313,8 @@ void Scene::DrawGui(GLFWwindow* window) {
     }
 
     ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+
+    ImGui::SliderFloat("Tessellation Level", &tessellationFactor, 1.0f, 64.0f);
     ImGui::End();
 
     // Draw FBO to ImGui window