Optionally expose time to screen shaders (#1700)

* Optionally expose time to screen shaders

Since that collides with damage tracking, it will only be done, when
damage tracking is disabled, meaning this comes at no cost for everyone
not using time.

* Rename m_Timer to m_tGlobalTimer

src/render/OpenGL.cpp

@@ -31,6 +31,8 @@ CHyprOpenGLImpl::CHyprOpenGLImpl() {
     pixman_region32_init(&m_rOriginalDamageRegion);
 
     RASSERT(eglMakeCurrent(wlr_egl_get_display(g_pCompositor->m_sWLREGL), EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT), "Couldn't unset current EGL!");
+
+    m_tGlobalTimer.reset();
 }
 
 GLuint CHyprOpenGLImpl::createProgram(const std::string& vert, const std::string& frag, bool dynamic) {
@@ -312,6 +314,13 @@ void CHyprOpenGLImpl::applyScreenShader(const std::string& path) {
 
     m_sFinalScreenShader.proj = glGetUniformLocation(m_sFinalScreenShader.program, "proj");
     m_sFinalScreenShader.tex  = glGetUniformLocation(m_sFinalScreenShader.program, "tex");
+    m_sFinalScreenShader.time = glGetUniformLocation(m_sFinalScreenShader.program, "time");
+    if (m_sFinalScreenShader.time != -1 && g_pConfigManager->getInt("debug:damage_tracking") != 0) {
+        // The screen shader uses the "time" uniform
+        // Since the screen shader could change every frame, damage tracking *needs* to be disabled
+        g_pConfigManager->addParseError("Screen shader: Screen shader uses uniform 'time', which requires debug:damage_tracking to be switched off.\n"
+                                        "WARNING: Disabling damage tracking will *massively* increase GPU utilization!");
+    }
     m_sFinalScreenShader.texAttrib = glGetAttribLocation(m_sFinalScreenShader.program, "texcoord");
     m_sFinalScreenShader.posAttrib = glGetAttribLocation(m_sFinalScreenShader.program, "pos");
 }
@@ -523,6 +532,14 @@ void CHyprOpenGLImpl::renderTextureInternalWithDamage(const CTexture& tex, wlr_b
     glUniformMatrix3fv(shader->proj, 1, GL_FALSE, glMatrix);
 #endif
     glUniform1i(shader->tex, 0);
+
+    if (usingFinalShader && g_pConfigManager->getInt("debug:damage_tracking") == 0) {
+        glUniform1f(shader->time, m_tGlobalTimer.getSeconds());
+    } else if (usingFinalShader) {
+        // Don't let time be unitialised
+        glUniform1f(shader->time, 0.f);
+    }
+
     if (!usingFinalShader) {
         glUniform1f(shader->alpha, alpha);
         glUniform1i(shader->discardOpaque, (int)discardOpaque);

src/render/OpenGL.hpp

@@ -3,6 +3,7 @@
 #include "../defines.hpp"
 #include "../helpers/Monitor.hpp"
 #include "../helpers/Color.hpp"
+#include "../helpers/Timer.hpp"
 #include <list>
 #include <unordered_map>
 
@@ -134,6 +135,7 @@ class CHyprOpenGLImpl {
     bool              m_bApplyFinalShader = false;
 
     CShader           m_sFinalScreenShader;
+    CTimer            m_tGlobalTimer;
 
     GLuint            createProgram(const std::string&, const std::string&, bool dynamic = false);
     GLuint            compileShader(const GLuint&, std::string, bool dynamic = false);

src/render/Shader.hpp

@@ -37,6 +37,8 @@ class CShader {
     GLint  gradientLength;
     GLint  angle;
 
+    GLint  time;
+
     GLint  getUniformLocation(const std::string&);
 
     void   destroy();