Uncap water ripples

src/hardware/hw_main.c

@@ -6786,7 +6786,7 @@ void HWR_DoPostProcessor(player_t *player)
 	{
 		// 10 by 10 grid. 2 coordinates (xy)
 		float v[SCREENVERTS][SCREENVERTS][2];
-		static double disStart = 0;
+		float disStart = (leveltime-1) + FIXED_TO_FLOAT(rendertimefrac);
 
 		UINT8 x, y;
 		INT32 WAVELENGTH;
@@ -6817,8 +6817,6 @@ void HWR_DoPostProcessor(player_t *player)
 			}
 		}
 		HWD.pfnPostImgRedraw(v);
-		if (!(paused || P_AutoPause()))
-			disStart += FIXED_TO_FLOAT(renderdeltatics);
 
 		// Capture the screen again for screen waving on the intermission
 		if(gamestate != GS_INTERMISSION)

src/hardware/r_opengl/r_opengl.c

@@ -21,6 +21,7 @@
 
 #include <stdarg.h>
 #include <math.h>
+#include "../../r_local.h" // For rendertimefrac, used for the leveltime shader uniform
 #include "r_opengl.h"
 #include "r_vbo.h"
 
@@ -616,7 +617,7 @@ typedef struct gl_shaderstate_s
 static gl_shaderstate_t gl_shaderstate;
 
 // Shader info
-static INT32 shader_leveltime = 0;
+static float shader_leveltime = 0;
 
 // Lactozilla: Shader functions
 static boolean Shader_CompileProgram(gl_shader_t *shader, GLint i, const GLchar *vert_shader, const GLchar *frag_shader);
@@ -976,7 +977,7 @@ EXPORT void HWRAPI(SetShaderInfo) (hwdshaderinfo_t info, INT32 value)
 	switch (info)
 	{
 		case HWD_SHADERINFO_LEVELTIME:
-			shader_leveltime = value;
+			shader_leveltime = (((float)(value-1)) + FIXED_TO_FLOAT(rendertimefrac)) / TICRATE;
 			break;
 		default:
 			break;
@@ -2046,7 +2047,7 @@ static void Shader_SetUniforms(FSurfaceInfo *Surface, GLRGBAFloat *poly, GLRGBAF
 			UNIFORM_1(shader->uniforms[gluniform_fade_end], Surface->LightInfo.fade_end, pglUniform1f);
 		}
 
-		UNIFORM_1(shader->uniforms[gluniform_leveltime], ((float)shader_leveltime) / TICRATE, pglUniform1f);
+		UNIFORM_1(shader->uniforms[gluniform_leveltime], shader_leveltime, pglUniform1f);
 
 		#undef UNIFORM_1
 		#undef UNIFORM_2

src/r_plane.c

@@ -15,6 +15,7 @@
 
 #include "doomdef.h"
 #include "console.h"
+#include "m_easing.h" // For Easing_InOutSine, used in R_UpdatePlaneRipple
 #include "g_game.h"
 #include "p_setup.h" // levelflats
 #include "p_slopes.h"
@@ -137,8 +138,14 @@ static void R_CalculatePlaneRipple(angle_t angle)
 
 static void R_UpdatePlaneRipple(void)
 {
-	ds_waterofs = (leveltime & 1)*16384;
+	// ds_waterofs oscillates between 0 and 16384 every other tic
-	planeripple.offset = (leveltime * 140);
+	// Now that frame interpolation is a thing, HOW does it oscillate?
+	// The difference between linear interpolation and a sine wave is miniscule here,
+	// but a sine wave is ever so slightly smoother and sleeker
+	ds_waterofs = Easing_InOutSine(((leveltime & 1)*FRACUNIT) + rendertimefrac,16384,0);
+
+	// Meanwhile, planeripple.offset just counts up, so it gets simple linear interpolation
+	planeripple.offset = ((leveltime-1)*140) + ((rendertimefrac*140) / FRACUNIT);
 }
 
 static void R_MapPlane(INT32 y, INT32 x1, INT32 x2)

src/v_video.c

@@ -3606,7 +3606,8 @@ void V_DoPostProcessor(INT32 view, postimg_t type, INT32 param)
 		UINT8 *tmpscr = screens[4];
 		UINT8 *srcscr = screens[0];
 		INT32 y;
-		angle_t disStart = (leveltime * 128) & FINEMASK; // in 0 to FINEANGLE
+		// Set disStart to a range from 0 to FINEANGLE, incrementing by 128 per tic
+		angle_t disStart = (((leveltime-1)*128) + (rendertimefrac / (FRACUNIT/128))) & FINEMASK;
 		INT32 newpix;
 		INT32 sine;
 		//UINT8 *transme = R_GetTranslucencyTable(tr_trans50);
@@ -3729,8 +3730,11 @@ Unoptimized version
 			heatindex[view] %= height;
 		}
 
+		if (renderisnewtic) // This isn't interpolated... but how do you interpolate a one-pixel shift?
+		{
 			heatindex[view]++;
 			heatindex[view] %= vid.height;
+		}
 
 		VID_BlitLinearScreen(tmpscr+vid.width*vid.bpp*yoffset, screens[0]+vid.width*vid.bpp*yoffset,
 				vid.width*vid.bpp, height, vid.width*vid.bpp, vid.width);