Merge pull request #751 from Cheesse/master

Use reversed z depth for D3D backend

src/Camera.c

@@ -27,7 +27,7 @@ static void Camera_OnRawMovement(float deltaX, float deltaY) {
 static void PerspectiveCamera_GetProjection(struct Matrix* proj) {
 	float fovy = Game_Fov * MATH_DEG2RAD;
 	float aspectRatio = (float)Game.Width / (float)Game.Height;
-	Matrix_PerspectiveFieldOfView(proj, fovy, aspectRatio, Gfx.MinZNear, (float)Game_ViewDistance);
+	Gfx_CalcPerspectiveMatrix(fovy, aspectRatio, Gfx.MinZNear, (float)Game_ViewDistance, proj);
 }
 
 static void PerspectiveCamera_GetView(struct Matrix* mat) {

src/Game.c

@@ -600,7 +600,9 @@ static void Game_RenderFrame(double delta) {
 	Gfx_Clear();
 	Camera.CurrentPos = Camera.Active->GetPosition(t);
 	UpdateViewMatrix();
+
 	Gfx_LoadMatrix(MATRIX_PROJECTION, &Gfx.Projection);
+
 	Gfx_LoadMatrix(MATRIX_VIEW, &Gfx.View);
 
 	if (!Gui_GetBlocksWorld()) {

src/Graphics.c

@@ -372,7 +372,11 @@ static void FindCompatibleDepthFormat(void) {
 	for (i = 0; i < Array_Elems(formats); i++) {
 		depthFormat = formats[i];
 		res = IDirect3D9_CheckDepthStencilMatch(d3d, D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, viewFormat, viewFormat, depthFormat);
-		if (!res) return;
+		if (!res) {
+			/* With reversed z depth, the near Z plane can be set much lower with more depth buffer bits. */
+			Gfx.MinZNear = i > 3 ? 0.05f : 0.001953125f;
+			return;
+		}
 	}
 	Logger_Abort("Failed to create depth buffer. Graphics drivers may not be installed.");
 }
@@ -427,7 +431,6 @@ void Gfx_Create(void) {
 	FindCompatibleViewFormat();
 	FindCompatibleDepthFormat();
 
-	Gfx.MinZNear        = 0.05f;
 	customMipmapsLevels = true;
 	Gfx.ManagedTextures = true;
 	Gfx.Created         = true;
@@ -477,7 +480,7 @@ static void Gfx_RestoreState(void) {
 	IDirect3DDevice9_SetRenderState(device, D3DRS_ALPHAREF,  127);
 	IDirect3DDevice9_SetRenderState(device, D3DRS_SRCBLEND,  D3DBLEND_SRCALPHA);
 	IDirect3DDevice9_SetRenderState(device, D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA);
-	IDirect3DDevice9_SetRenderState(device, D3DRS_ZFUNC,     D3DCMP_LESSEQUAL);
+	IDirect3DDevice9_SetRenderState(device, D3DRS_ZFUNC,     D3DCMP_GREATEREQUAL);
 	D3D9_RestoreRenderStates();
 }
 
@@ -911,6 +914,9 @@ void Gfx_CalcOrthoMatrix(float width, float height, struct Matrix* matrix) {
 }
 void Gfx_CalcPerspectiveMatrix(float fov, float aspect, float zNear, float zFar, struct Matrix* matrix) {
 	Matrix_PerspectiveFieldOfView(matrix, fov, aspect, zNear, zFar);
+	/* Adjust the projection matrix to produce reversed Z values. */
+	matrix->Row2.Z = -matrix->Row2.Z - 1.0f;
+	matrix->Row3.Z = -matrix->Row3.Z;
 }
 
 
@@ -966,7 +972,7 @@ void Gfx_BeginFrame(void) {
 
 void Gfx_Clear(void) {
 	DWORD flags = D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER;
-	cc_result res = IDirect3DDevice9_Clear(device, 0, NULL, flags, gfx_clearCol, 1.0f, 0);
+	cc_result res = IDirect3DDevice9_Clear(device, 0, NULL, flags, gfx_clearCol, 0.0f, 0);
 	if (res) Logger_Abort2(res, "D3D9_Clear");
 }
 
@@ -1808,6 +1814,7 @@ void Gfx_SetFogMode(FogFunc func) {
 void Gfx_SetTexturing(cc_bool enabled) { }
 void Gfx_SetAlphaTest(cc_bool enabled) { gfx_alphaTest = enabled; SwitchProgram(); }
 
+void Gfx_PrepProjection(struct Matrix* matrix) { }
 void Gfx_LoadMatrix(MatrixType type, struct Matrix* matrix) {
 	if (type == MATRIX_VIEW || type == MATRIX_PROJECTION) {
 		if (type == MATRIX_VIEW)       _view = *matrix;
@@ -1982,6 +1989,7 @@ void Gfx_SetAlphaTest(cc_bool enabled) { gl_Toggle(GL_ALPHA_TEST); }
 static GLenum matrix_modes[3] = { GL_PROJECTION, GL_MODELVIEW, GL_TEXTURE };
 static int lastMatrix;
 
+void Gfx_PrepProjection(struct Matrix* matrix) { }
 void Gfx_LoadMatrix(MatrixType type, struct Matrix* matrix) {
 	if (type != lastMatrix) { lastMatrix = type; glMatrixMode(matrix_modes[type]); }
 	glLoadMatrixf((float*)matrix);

src/Vectors.c

@@ -2,6 +2,7 @@
 #include "ExtMath.h"
 #include "Funcs.h"
 #include "Constants.h"
+#include "Core.h"
 
 void Vec3_Lerp(Vec3* result, const Vec3* a, const Vec3* b, float blend) {
 	result->X = blend * (b->X - a->X) + a->X;
@@ -182,21 +183,16 @@ void Matrix_Orthographic(struct Matrix* result, float left, float right, float t
 static double Tan_Simple(double x) { return Math_Sin(x) / Math_Cos(x); }
 void Matrix_PerspectiveFieldOfView(struct Matrix* result, float fovy, float aspect, float zNear, float zFar) {
 	float c = zNear * (float)Tan_Simple(0.5f * fovy);
-	Matrix_PerspectiveOffCenter(result, -c * aspect, c * aspect, -c, c, zNear, zFar);
+	float zDelta = zNear - zFar;
-}
 
-void Matrix_PerspectiveOffCenter(struct Matrix* result, float left, float right, float bottom, float top, float zNear, float zFar) {
-	/* Transposed, source https://msdn.microsoft.com/en-us/library/dd373537(v=vs.85).aspx */
 	*result = Matrix_Identity;
 	result->Row3.W = 0.0f;
 
-	result->Row0.X = (2.0f * zNear) / (right - left);
+	result->Row0.X = zNear / (c * aspect);
-	result->Row1.Y = (2.0f * zNear) / (top - bottom);
+	result->Row1.Y = zNear / c;
-	result->Row3.Z = -(2.0f * zFar * zNear) / (zFar - zNear);
+	result->Row3.Z = (2.0f * zFar * zNear) / zDelta;
 
-	result->Row2.X = (right + left) / (right - left);
+	result->Row2.Z = (zFar + zNear) / zDelta;
-	result->Row2.Y = (top + bottom) / (top - bottom);
-	result->Row2.Z = -(zFar + zNear) / (zFar - zNear);
 	result->Row2.W = -1.0f;
 }
 
@@ -276,10 +272,19 @@ void FrustumCulling_CalcFrustumEquations(struct Matrix* projection, struct Matri
 	frustum33 = clip[15] - clip[13];
 	FrustumCulling_Normalise(&frustum30, &frustum31, &frustum32, &frustum33);
 
-	/* Extract the FAR plane */
+	/* Extract the FAR plane (Different for each graphics backend) */
+#if defined(CC_BUILD_GL)
 	frustum40 = clip[3]  - clip[2];
 	frustum41 = clip[7]  - clip[6];
 	frustum42 = clip[11] - clip[10];
 	frustum43 = clip[15] - clip[14];
+#elif defined(CC_BUILD_D3D9)
+	frustum40 = clip[2];
+	frustum41 = clip[6];
+	frustum42 = clip[10];
+	frustum43 = clip[14];
+#else
+#error "Vectors.c: No graphics backend chosen."
+#endif
 	FrustumCulling_Normalise(&frustum40, &frustum41, &frustum42, &frustum43);
 }

src/Vectors.h

@@ -123,7 +123,6 @@ CC_API void Matrix_Mul(struct Matrix* result, const struct Matrix* left, const s
 
 void Matrix_Orthographic(struct Matrix* result, float left, float right, float top, float bottom, float zNear, float zFar);
 void Matrix_PerspectiveFieldOfView(struct Matrix* result, float fovy, float aspect, float zNear, float zFar);
-void Matrix_PerspectiveOffCenter(struct Matrix* result, float left, float right, float bottom, float top, float zNear, float zFar);
 void Matrix_LookRot(struct Matrix* result, Vec3 pos, Vec2 rot);
 
 cc_bool FrustumCulling_SphereInFrustum(float x, float y, float z, float radius);