Completed main levels to progress to text-rendering and 2d development.

- Only lessons left are geometry shaders and anti-aliasing
- will get to those later on soon
- need to do text rendering now

11 files changed, 235 insertions, 0 deletions

diff --git a/source/lessons/uniform buffer objects/shaders/blend_test.fs.glsl b/source/lessons/uniform buffer objects/shaders/blend_test.fs.glsl
new file mode 100644
index 0000000..23daa14
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/blend_test.fs.glsl
@@ -0,0 +1,14 @@
+#version 330 core
+
+
+in vec2 TexCoords;
+in vec3 VertexWorldPos;
+uniform sampler2D TexId;
+uniform vec4 hlt_color;
+out vec4 FragColor;
+
+void main() {
+    vec4 tex = texture(TexId, TexCoords);
+
+    FragColor = tex;
+}
diff --git a/source/lessons/uniform buffer objects/shaders/cubemap.fs.glsl b/source/lessons/uniform buffer objects/shaders/cubemap.fs.glsl
new file mode 100644
index 0000000..72dfe4c
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/cubemap.fs.glsl
@@ -0,0 +1,9 @@
+#version 330 core
+
+in vec3 TexCoords;
+uniform samplerCube skybox;
+out vec4 FragColor;
+
+void main() {
+  FragColor = texture(skybox, TexCoords);
+};
diff --git a/source/lessons/uniform buffer objects/shaders/cubemap.vs.glsl b/source/lessons/uniform buffer objects/shaders/cubemap.vs.glsl
new file mode 100644
index 0000000..956673a
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/cubemap.vs.glsl
@@ -0,0 +1,14 @@
+#version 330 core
+layout(location=0) in vec3 aPos;
+
+uniform mat4 Model;
+uniform mat4 View;
+uniform mat4 Projection;
+
+out vec3 TexCoords;
+
+void main() {
+  vec4 pos = Projection*View*vec4(aPos, 1.0);
+  gl_Position = vec4(pos.xyww);
+  TexCoords = aPos;
+};
diff --git a/source/lessons/uniform buffer objects/shaders/depth_test.fs.glsl b/source/lessons/uniform buffer objects/shaders/depth_test.fs.glsl
new file mode 100644
index 0000000..796d849
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/depth_test.fs.glsl
@@ -0,0 +1,30 @@
+#version 330 core
+
+
+in vec2 TexCoords;
+in vec3 VertexWorldPos;
+uniform sampler2D TexId;
+out vec4 FragColor;
+
+uniform float near = 0.1f;
+uniform float far = 100.0f;
+
+/* @note
+float linear_fragment_depth = MakeDepthLinear(non_linear_fragment_depth);
+float scaled_lfd = linear_fragment_depth/far;
+
+gives us the z value in eye space.
+This is purely for learning purposes.
+The equation used in MakeDepthLinear is derived from the PerspectiveProjectionMatrix.
+Take a look at the equation for that in the codebase 
+or here: https://www.songho.ca/opengl/gl_projectionmatrix.html
+*/
+float MakeDepthLinear(float depth) {
+  float ndc = 2.0f*depth - 1;
+  float linear_depth = (2.0 * far * near)/(far + near - ndc*(far - near));
+  return linear_depth;
+}
+
+void main() {
+    FragColor = texture(TexId, TexCoords);
+}
diff --git a/source/lessons/uniform buffer objects/shaders/depth_test.vs.glsl b/source/lessons/uniform buffer objects/shaders/depth_test.vs.glsl
new file mode 100644
index 0000000..827da20
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/depth_test.vs.glsl
@@ -0,0 +1,21 @@
+#version 330 core
+layout(location=0) in vec3 aPos;
+layout(location=1) in vec2 aTex;
+
+uniform mat4 Model;
+layout (std140) uniform Matrices {
+  mat4 View;        // start:  0      // end: 16 *  4 =  64
+  mat4 Projection;  // start: 64      // end: 64 + 64 = 128
+};
+
+out vec2 TexCoords;
+out vec3 VertexWorldPos;
+
+// @note: I still do not fully understand how the FragNormal calculation works. Need to make sure I intuitively 
+// get that
+
+void main() {
+  gl_Position = Projection*View*Model*vec4(aPos, 1.0);
+  VertexWorldPos = vec3(Model * vec4(aPos, 1.0));
+  TexCoords = aTex;
+};
diff --git a/source/lessons/uniform buffer objects/shaders/fbo.fs.glsl b/source/lessons/uniform buffer objects/shaders/fbo.fs.glsl
new file mode 100644
index 0000000..e12ad33
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/fbo.fs.glsl
@@ -0,0 +1,72 @@
+#version 330 core
+
+in vec2 TexCoords;
+uniform sampler2D TexId;
+out vec4 FragColor;
+
+vec4 filter_color_invert(vec4 color)
+{
+  vec4 res = vec4(vec3(1.0) - vec3(color), 1.0);
+  return res;
+}
+
+vec4 filter_color_grayscale(vec4 color)
+{
+  // we will need to average the colors
+  // float average = (color.x + color.y + color.z) / 3.0f;
+  // in reality, human our most sensitive towards green and least to blue, so will need to weight those
+  float average = 0.2126 * color.r + 0.7152 * color.g + 0.0722 * color.b;
+  vec4 res = vec4(vec3(average), 1.0);
+
+  return res;
+}
+
+// @note: different kernels for experimentation
+const float kernel_sharpen[9] = float[](
+    -1, -1, -1,
+    -1,  9, -1,
+    -1, -1, -1
+);
+
+const float kernel_blur[9] = float[](
+    1.0/16.0, 2.0/16.0, 1.0/16.0,
+    2.0/16.0, 4.0/16.0, 2.0/16.0,
+    1.0/16.0, 2.0/16.0, 1.0/16.0
+);
+
+const float kernel_edge_detection[9] = float[](
+    1,  1,  1,
+    1, -8,  1,
+    1,  1,  1
+);
+
+vec4 filter_kernal_effects() 
+{
+  const float offset = 1.0/300.0;
+  vec2 offsets[9] = vec2[](
+    vec2(-offset,  offset),    // top left
+    vec2(      0,  offset),    // top center
+    vec2( offset,  offset),    // top right
+    vec2(-offset,       0),    // center left
+    vec2(      0,       0),    // center center
+    vec2( offset,       0),    // center right
+    vec2(-offset, -offset),    // bot left
+    vec2(      0, -offset),    // bot center
+    vec2( offset, -offset)    // bot right
+  );
+
+  float kernal[9] = kernel_edge_detection;
+  vec3 kernalValue = vec3(0.0);
+  vec3 sampleTex[9];
+  for (int i=0; i<9; i++) {
+    sampleTex[i] = vec3(texture(TexId, TexCoords + offsets[i]));
+    kernalValue += (kernal[i] * sampleTex[i]);
+  }
+
+  vec4 res = vec4(kernalValue, 1.0);
+  return res;
+}
+
+void main() {
+    FragColor = texture(TexId, TexCoords);
+}
diff --git a/source/lessons/uniform buffer objects/shaders/fbo.vs.glsl b/source/lessons/uniform buffer objects/shaders/fbo.vs.glsl
new file mode 100644
index 0000000..82d7211
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/fbo.vs.glsl
@@ -0,0 +1,10 @@
+#version 330 core
+layout(location=0) in vec3 aPos;
+layout(location=1) in vec2 aTex;
+
+out vec2 TexCoords;
+
+void main() {
+  gl_Position = vec4(aPos.x, aPos.y, 0.0f, 1.0f);
+  TexCoords = aTex;
+};
diff --git a/source/lessons/uniform buffer objects/shaders/refl.fs.glsl b/source/lessons/uniform buffer objects/shaders/refl.fs.glsl
new file mode 100644
index 0000000..6d28392
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/refl.fs.glsl
@@ -0,0 +1,14 @@
+#version 330 core
+
+in vec3 Normal;
+in vec3 Position;
+
+uniform samplerCube skybox;
+uniform vec3 cameraPos;
+out vec4 FragColor;
+
+void main() {
+  vec3 I = normalize(Position - cameraPos);
+  vec3 R = reflect(I, normalize(Normal)); 
+  FragColor = vec4(texture(skybox, R).rgb, 1.0);
+};
diff --git a/source/lessons/uniform buffer objects/shaders/refl.vs.glsl b/source/lessons/uniform buffer objects/shaders/refl.vs.glsl
new file mode 100644
index 0000000..b8f2b97
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/refl.vs.glsl
@@ -0,0 +1,16 @@
+#version 330 core
+layout(location=0) in vec3 aPos;
+layout(location=1) in vec3 aNormal;
+
+uniform mat4 View;
+uniform mat4 Model;
+uniform mat4 Projection;
+
+out vec3 Normal;
+out vec3 Position;
+
+void main() {
+  Normal = mat3(transpose(inverse(Model))) * aNormal;
+  Position = vec3(Model * vec4(aPos, 1.0));
+  gl_Position = Projection * View * Model * vec4(aPos, 1.0);
+};
diff --git a/source/lessons/uniform buffer objects/shaders/refr.fs.glsl b/source/lessons/uniform buffer objects/shaders/refr.fs.glsl
new file mode 100644
index 0000000..6747ded
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/refr.fs.glsl
@@ -0,0 +1,15 @@
+#version 330 core
+
+in vec3 Normal;
+in vec3 Position;
+
+uniform samplerCube skybox;
+uniform vec3 cameraPos;
+out vec4 FragColor;
+
+void main() {
+  float refr_ratio = 1.0/1.52;
+  vec3 I = normalize(Position - cameraPos);
+  vec3 R = refract(I, normalize(Normal), refr_ratio); 
+  FragColor = vec4(texture(skybox, R).rgb, 1.0);
+};
diff --git a/source/lessons/uniform buffer objects/shaders/refr.vs.glsl b/source/lessons/uniform buffer objects/shaders/refr.vs.glsl
new file mode 100644
index 0000000..0554f0a
--- /dev/null
+++ b/source/lessons/uniform buffer objects/shaders/refr.vs.glsl
@@ -0,0 +1,20 @@
+#version 330 core
+layout(location=0) in vec3 aPos;
+layout(location=1) in vec3 aNormal;
+
+uniform mat4 View;
+uniform mat4 Model;
+uniform mat4 Projection;
+
+out vec3 Normal;
+out vec3 Position;
+
+void main() {
+  // @note: This is the calculation for getting the normal vector
+  // one that is unaffected by non-uniform scaling that is.
+  // look at the lighting chapter in learnopengl.com to understand this more
+  Normal = mat3(transpose(inverse(Model))) * aNormal;
+  Position = vec3(Model * vec4(aPos, 1.0));
+  gl_Position = Projection * View * Model * vec4(aPos, 1.0);
+};
+