From 45526c276953355074f845f4531a741ddc542e5e Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@zdoom.fake>
Date: Sun, 5 Apr 2015 18:55:21 +0200
Subject: [PATCH] - basics for using hardware clip planes to split translucent
 stuff by 3D floor planes.

---
 src/gl/renderer/gl_renderstate.cpp |  2 ++
 src/gl/renderer/gl_renderstate.h   | 23 +++++++++++++++++++++++
 src/gl/shaders/gl_shader.cpp       |  1 +
 src/gl/shaders/gl_shader.h         | 23 +++++++++++++++++++++++
 4 files changed, 49 insertions(+)

diff --git a/src/gl/renderer/gl_renderstate.cpp b/src/gl/renderer/gl_renderstate.cpp
index 358c9fe7f2..15b046349c 100644
--- a/src/gl/renderer/gl_renderstate.cpp
+++ b/src/gl/renderer/gl_renderstate.cpp
@@ -86,6 +86,7 @@ void FRenderState::Reset()
 	mSpecialEffect = EFF_NONE;
 	mClipHeightTop = 65536.f;
 	mClipHeightBottom = -65536.f;
+	ClearClipSplit();
 
 	stSrcBlend = stDstBlend = -1;
 	stBlendEquation = -1;
@@ -141,6 +142,7 @@ bool FRenderState::ApplyShader()
 	activeShader->muTimer.Set(gl_frameMS * mShaderTimer / 1000.f);
 	activeShader->muAlphaThreshold.Set(mAlphaThreshold);
 	activeShader->muLightIndex.Set(mLightIndex);	// will always be -1 for now
+	activeShader->muClipSplit.Set(mClipSplit);
 
 	if (mGlowEnabled)
 	{
diff --git a/src/gl/renderer/gl_renderstate.h b/src/gl/renderer/gl_renderstate.h
index 8c3b60772a..74065fe4ce 100644
--- a/src/gl/renderer/gl_renderstate.h
+++ b/src/gl/renderer/gl_renderstate.h
@@ -73,6 +73,7 @@ class FRenderState
 	PalEntry mFogColor;
 	PalEntry mObjectColor;
 	FStateVec4 mDynColor;
+	float mClipSplit[2];
 
 	int mEffectState;
 	int mColormapState;
@@ -279,6 +280,28 @@ public:
 		return mFogColor;
 	}
 
+	void SetClipSplit(float bottom, float top)
+	{
+		mClipSplit[0] = bottom;
+		mClipSplit[1] = top;
+	}
+
+	void SetClipSplit(float *vals)
+	{
+		memcpy(mClipSplit, vals, 2 * sizeof(float));
+	}
+
+	void GetClipSplit(float *out)
+	{
+		memcpy(out, mClipSplit, 2 * sizeof(float));
+	}
+
+	void ClearClipSplit()
+	{
+		mClipSplit[0] = -1000000.f;
+		mClipSplit[1] = 1000000.f;
+	}
+
 	void BlendFunc(int src, int dst)
 	{
 		if (!gl_direct_state_change)
diff --git a/src/gl/shaders/gl_shader.cpp b/src/gl/shaders/gl_shader.cpp
index 7c04bdf454..2955cf7c89 100644
--- a/src/gl/shaders/gl_shader.cpp
+++ b/src/gl/shaders/gl_shader.cpp
@@ -205,6 +205,7 @@ bool FShader::Load(const char * name, const char * vert_prog_lump, const char *
 	muTextureMode.Init(hShader, "uTextureMode");
 	muCameraPos.Init(hShader, "uCameraPos");
 	muLightParms.Init(hShader, "uLightAttr");
+	muClipSplit.Init(hShader, "uClipSplit");
 	muColormapStart.Init(hShader, "uFixedColormapStart");
 	muColormapRange.Init(hShader, "uFixedColormapRange");
 	muLightIndex.Init(hShader, "uLightIndex");
diff --git a/src/gl/shaders/gl_shader.h b/src/gl/shaders/gl_shader.h
index 8b6f7b4a6e..c5baceceb1 100644
--- a/src/gl/shaders/gl_shader.h
+++ b/src/gl/shaders/gl_shader.h
@@ -103,6 +103,28 @@ public:
 	}
 };
 
+class FBufferedUniform2f
+{
+	float mBuffer[2];
+	int mIndex;
+
+public:
+	void Init(GLuint hShader, const GLchar *name)
+	{
+		mIndex = glGetUniformLocation(hShader, name);
+		memset(mBuffer, 0, sizeof(mBuffer));
+	}
+
+	void Set(const float *newvalue)
+	{
+		if (memcmp(newvalue, mBuffer, sizeof(mBuffer)))
+		{
+			memcpy(mBuffer, newvalue, sizeof(mBuffer));
+			glUniform2fv(mIndex, 1, newvalue);
+		}
+	}
+};
+
 class FBufferedUniform4f
 {
 	float mBuffer[4];
@@ -184,6 +206,7 @@ class FShader
 	FBufferedUniform1i muTextureMode;
 	FBufferedUniform4f muCameraPos;
 	FBufferedUniform4f muLightParms;
+	FBufferedUniform2f muClipSplit;
 	FUniform1i muFixedColormap;
 	FUniform4f muColormapStart;
 	FUniform4f muColormapRange;