Added tutorial 55

Common/Shaders/infinite_grid.fs

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+/*
+
+        Copyright 2024 Etay Meiri
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#version 330
+
+in vec3 WorldPos;
+
+layout(location = 0) out vec4 FragColor;
+
+uniform vec3 gCameraWorldPos;
+uniform float gGridSize = 100.0;
+uniform float gGridMinPixelsBetweenCells = 2.0;
+uniform float gGridCellSize = 0.025;
+uniform vec4 gGridColorThin = vec4(0.5, 0.5, 0.5, 1.0);
+uniform vec4 gGridColorThick = vec4(0.0, 0.0, 0.0, 1.0);
+
+
+float log10(float x)
+{
+    float f = log(x) / log(10.0);
+    return f;
+}
+
+
+float satf(float x)
+{
+    float f = clamp(x, 0.0, 1.0);
+    return f;
+}
+
+
+vec2 satv(vec2 x)
+{
+    vec2 v = clamp(x, vec2(0.0), vec2(1.0));
+    return v;
+}
+
+
+float max2(vec2 v)
+{
+    float f = max(v.x, v.y);
+    return f;
+}
+
+
+void main()
+{
+    vec2 dvx = vec2(dFdx(WorldPos.x), dFdy(WorldPos.x));
+    vec2 dvy = vec2(dFdx(WorldPos.z), dFdy(WorldPos.z));
+
+    float lx = length(dvx);
+    float ly = length(dvy);
+
+    vec2 dudv = vec2(lx, ly);
+
+    float l = length(dudv);
+
+    float LOD = max(0.0, log10(l * gGridMinPixelsBetweenCells / gGridCellSize) + 1.0);
+
+    float GridCellSizeLod0 = gGridCellSize * pow(10.0, floor(LOD));
+    float GridCellSizeLod1 = GridCellSizeLod0 * 10.0;
+    float GridCellSizeLod2 = GridCellSizeLod1 * 10.0;
+
+    dudv *= 4.0;
+
+    vec2 mod_div_dudv = mod(WorldPos.xz, GridCellSizeLod0) / dudv;
+    float Lod0a = max2(vec2(1.0) - abs(satv(mod_div_dudv) * 2.0 - vec2(1.0)) );
+
+    mod_div_dudv = mod(WorldPos.xz, GridCellSizeLod1) / dudv;
+    float Lod1a = max2(vec2(1.0) - abs(satv(mod_div_dudv) * 2.0 - vec2(1.0)) );
+
+    mod_div_dudv = mod(WorldPos.xz, GridCellSizeLod2) / dudv;
+    float Lod2a = max2(vec2(1.0) - abs(satv(mod_div_dudv) * 2.0 - vec2(1.0)) );
+
+    float LOD_fade = fract(LOD);
+    vec4 Color;
+
+    if (Lod2a > 0.0) {
+        Color = gGridColorThick;
+        Color.a *= Lod2a;
+    } else {
+        if (Lod1a > 0.0) {
+            Color = mix(gGridColorThick, gGridColorThin, LOD_fade);
+	        Color.a *= Lod1a;
+        } else {
+            Color = gGridColorThin;
+	        Color.a *= (Lod0a * (1.0 - LOD_fade));
+        }
+    }
+
+    float OpacityFalloff = (1.0 - satf(length(WorldPos.xz - gCameraWorldPos.xz) / gGridSize));
+
+    Color.a *= OpacityFalloff;
+
+    FragColor = Color;
+}

Common/Shaders/infinite_grid.vs

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+/*
+
+        Copyright 2024 Etay Meiri
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#version 330
+
+out vec3 WorldPos;
+
+uniform mat4 gVP = mat4(1.0);
+uniform float gGridSize = 100.0;
+uniform vec3 gCameraWorldPos;
+
+const vec3 Pos[4] = vec3[4](
+    vec3(-1.0, 0.0, -1.0),      // bottom left
+    vec3( 1.0, 0.0, -1.0),      // bottom right
+    vec3( 1.0, 0.0,  1.0),      // top right
+    vec3(-1.0, 0.0,  1.0)       // top left
+);
+
+const int Indices[6] = int[6](0, 2, 1, 2, 0, 3);
+
+
+void main()
+{
+    int Index = Indices[gl_VertexID];
+    vec3 vPos3 = Pos[Index] * gGridSize;
+
+    vPos3.x += gCameraWorldPos.x;
+    vPos3.z += gCameraWorldPos.z;
+
+    vec4 vPos4 = vec4(vPos3, 1.0);
+
+    gl_Position = gVP * vPos4;
+
+    WorldPos = vPos3;
+}

Common/ogldev_infinite_grid.cpp

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+/*
+
+        Copyright 2024 Etay Meiri
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#include "ogldev_infinite_grid.h"
+
+
+InfiniteGrid::InfiniteGrid()
+{
+
+}
+
+
+void InfiniteGrid::Init()
+{
+    if (!m_infiniteGridTech.Init()) {
+        printf("Error initializing the infinite grid technique\n");
+        exit(1);
+    }
+}
+
+
+void InfiniteGrid::Render(const InfiniteGridConfig& Config, const Matrix4f& VP, const Vector3f& CameraPos)
+{
+    GLint CurProg = 0;
+    glGetIntegerv(GL_CURRENT_PROGRAM, &CurProg);
+
+    m_infiniteGridTech.Enable();
+
+    m_infiniteGridTech.SetVP(VP);
+    m_infiniteGridTech.SetCameraWorldPos(CameraPos);
+    m_infiniteGridTech.SetCellSize(Config.CellSize);
+
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+    glDrawArraysInstancedBaseInstance(GL_TRIANGLES, 0, 6, 1, 0);
+    glDisable(GL_BLEND);
+
+    glUseProgram(CurProg);
+}

Common/ogldev_infinite_grid_technique.cpp

@@ -0,0 +1,72 @@
+/*
+
+        Copyright 2023 Etay Meiri
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#include "ogldev_infinite_grid_technique.h"
+
+
+bool InfiniteGridTechnique::Init()
+{
+    if (!Technique::Init()) {
+        return false;
+    }
+
+    if (!AddShader(GL_VERTEX_SHADER, "../Common/Shaders/infinite_grid.vs")) {
+        return false;
+    }
+
+    if (!AddShader(GL_FRAGMENT_SHADER, "../Common/Shaders/infinite_grid.fs")) {
+        return false;
+    }
+
+    if (!Finalize()) {
+        return false;
+    }
+
+    return InitCommon();
+}
+
+
+bool InfiniteGridTechnique::InitCommon()
+{
+    GET_UNIFORM_AND_CHECK(VPLoc, "gVP");
+    GET_UNIFORM_AND_CHECK(CameraWorldPosLoc, "gCameraWorldPos");
+    GET_UNIFORM_AND_CHECK(GridCellSizeLoc, "gGridCellSize");
+
+    return true;
+}
+
+
+void InfiniteGridTechnique::SetVP(const Matrix4f& VP)
+{
+    glUniformMatrix4fv(VPLoc, 1, GL_TRUE, (const GLfloat*)VP.m);
+}
+
+
+void InfiniteGridTechnique::SetCameraWorldPos(const Vector3f& CameraWorldPos)
+{
+    glUniform3f(CameraWorldPosLoc, CameraWorldPos.x, CameraWorldPos.y, CameraWorldPos.z);
+}
+
+
+void InfiniteGridTechnique::SetCellSize(float CellSize)
+{
+    glUniform1f(GridCellSizeLoc, CellSize);
+}
+
+

Include/ogldev_infinite_grid.h

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+/*
+
+        Copyright 2024 Etay Meiri
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#pragma once
+
+
+#include "ogldev_infinite_grid_technique.h"
+
+struct InfiniteGridConfig {
+    float Size = 100.0f;
+    float CellSize = 0.025f;
+    Vector4f ColorThin = Vector4f(0.5f, 0.5f, 0.5f, 1.0f);
+    Vector4f ColorThick = Vector4f(0.0f, 0.0f, 0.0f, 1.0f);
+    float MinPixelsBetweenCells = 2.0f;
+};
+
+
+class InfiniteGrid
+{
+public:
+    InfiniteGrid();
+
+    void Init();
+
+    void Render(const InfiniteGridConfig& Config, const Matrix4f& VP, const Vector3f& CameraPos);
+
+private:
+
+    InfiniteGridTechnique m_infiniteGridTech;
+};

Include/ogldev_infinite_grid_technique.h

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+/*
+
+        Copyright 2024 Etay Meiri
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include "ogldev_math_3d.h"
+#include "ogldev_util.h"
+#include "technique.h"
+
+
+class InfiniteGridTechnique : public Technique
+{
+public:
+    InfiniteGridTechnique() {}
+
+    virtual bool Init();
+
+    void SetVP(const Matrix4f& VP);
+    void SetCameraWorldPos(const Vector3f& CameraWorldPos);
+    void SetCellSize(float CellSize);
+
+private:
+    bool InitCommon();
+
+    GLuint VPLoc = INVALID_UNIFORM_LOCATION;
+    GLuint CameraWorldPosLoc = INVALID_UNIFORM_LOCATION;
+    GLuint GridCellSizeLoc = INVALID_UNIFORM_LOCATION;
+};
+