[retro-gtk/wip/aplazas/gl-display] draw the texture with scanlines
- From: Adrien Plazas <aplazas src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [retro-gtk/wip/aplazas/gl-display] draw the texture with scanlines
- Date: Tue, 14 Nov 2017 13:30:25 +0000 (UTC)
commit f3388ea60c5e325a27222e10413e56ccbb20959b
Author: Adrien Plazas <kekun plazas laposte net>
Date: Tue Nov 14 14:03:17 2017 +0100
draw the texture with scanlines
retro-gtk/retro-gl-display-fragment.glsl | 16 ++--
retro-gtk/retro-gl-display-vertex.glsl | 6 +-
retro-gtk/retro-gl-display.c | 82 +++++++++++++++-----
retro-gtk/retro-gtk.gresource.xml | 3 +
retro-gtk/shaders/crt-simple.fs | 127 ++++++++++++++++++++++++++++++
retro-gtk/shaders/crt-simple.vs | 27 ++++++
retro-gtk/shaders/scanline.fs | 20 +++++
7 files changed, 253 insertions(+), 28 deletions(-)
---
diff --git a/retro-gtk/retro-gl-display-fragment.glsl b/retro-gtk/retro-gl-display-fragment.glsl
index aa70c52..93f7013 100644
--- a/retro-gtk/retro-gl-display-fragment.glsl
+++ b/retro-gtk/retro-gl-display-fragment.glsl
@@ -1,11 +1,13 @@
-#version 150 core
+#version 150
-in vec2 texture_coordinates_frag;
-out vec4 out_color;
+uniform sampler2D source[];
-uniform sampler2D video;
+in Vertex {
+ vec2 texCoord;
+};
-void main ()
-{
- out_color = texture (video, texture_coordinates_frag);
+out vec4 fragColor;
+
+void main() {
+ fragColor = texture(source[0], texCoord);
}
diff --git a/retro-gtk/retro-gl-display-vertex.glsl b/retro-gtk/retro-gl-display-vertex.glsl
index 529d345..52caf7c 100644
--- a/retro-gtk/retro-gl-display-vertex.glsl
+++ b/retro-gtk/retro-gl-display-vertex.glsl
@@ -3,13 +3,15 @@
in vec2 position;
in vec2 texture_coordinates;
-out vec2 texture_coordinates_frag;
+out Vertex {
+ vec2 texCoord;
+} vertexOut;
uniform float relative_aspect_ratio;
void main ()
{
- texture_coordinates_frag = texture_coordinates;
+ vertexOut.texCoord = texture_coordinates;
if (relative_aspect_ratio > 1.0f)
gl_Position = vec4 (position.x / relative_aspect_ratio,
position.y,
diff --git a/retro-gtk/retro-gl-display.c b/retro-gtk/retro-gl-display.c
index 13b693c..fb637e1 100644
--- a/retro-gtk/retro-gl-display.c
+++ b/retro-gtk/retro-gl-display.c
@@ -78,18 +78,39 @@ typedef struct {
} texture_coordinates;
} RetroVertex;
-float vertices[] = {
+static float vertices[] = {
-1.0f, 1.0f, 0.0f, 0.0f, // Top-left
1.0f, 1.0f, 1.0f, 0.0f, // Top-right
1.0f, -1.0f, 1.0f, 1.0f, // Bottom-right
-1.0f, -1.0f, 0.0f, 1.0f, // Bottom-left
};
-GLuint elements[] = {
+static GLuint elements[] = {
0, 1, 2,
2, 3, 0,
};
+static GLuint
+create_shader_from_resource (GLenum shader_type,
+ const char *path,
+ GResourceLookupFlags lookup_flags,
+ GError **error)
+{
+ GBytes *source_bytes;
+ const gchar *source;
+ GLuint shader;
+
+ // TODO Handle the error properly.
+ source_bytes = g_resources_lookup_data (path, lookup_flags, error);
+ source = g_bytes_get_data (source_bytes, NULL);
+ shader = glCreateShader (shader_type);
+ glShaderSource (shader, 1, &source, NULL);
+ glCompileShader (shader);
+ g_bytes_unref (source_bytes);
+
+ return shader;
+}
+
static void
retro_gl_display_realize (RetroGLDisplay *self)
{
@@ -99,8 +120,6 @@ retro_gl_display_realize (RetroGLDisplay *self)
GLuint vertex_shader;
GLuint fragment_shader;
GLuint shader_program;
- GBytes *shader_source_bytes;
- const gchar *shader_source;
gtk_gl_area_make_current (GTK_GL_AREA (self));
@@ -115,21 +134,17 @@ retro_gl_display_realize (RetroGLDisplay *self)
glBindBuffer (GL_ELEMENT_ARRAY_BUFFER, element_buffer_object);
glBufferData (GL_ELEMENT_ARRAY_BUFFER, sizeof (elements), elements, GL_STATIC_DRAW);
- // Prepare the vertex shader
- shader_source_bytes = g_resources_lookup_data ("/org/gnome/Retro/retro-gl-display-vertex.glsl", 0, NULL);
- shader_source = g_bytes_get_data (shader_source_bytes, NULL);
- vertex_shader = glCreateShader (GL_VERTEX_SHADER);
- glShaderSource (vertex_shader, 1, &shader_source, NULL);
- glCompileShader (vertex_shader);
- g_bytes_unref (shader_source_bytes);
-
- // Prepare the fragment shader
- shader_source_bytes = g_resources_lookup_data ("/org/gnome/Retro/retro-gl-display-fragment.glsl", 0, NULL);
- shader_source = g_bytes_get_data (shader_source_bytes, NULL);
- fragment_shader = glCreateShader (GL_FRAGMENT_SHADER);
- glShaderSource (fragment_shader, 1, &shader_source, NULL);
- glCompileShader (fragment_shader);
- g_bytes_unref (shader_source_bytes);
+ vertex_shader =
+ create_shader_from_resource (GL_VERTEX_SHADER,
+ "/org/gnome/Retro/retro-gl-display-vertex.glsl",
+ 0,
+ NULL);
+
+ fragment_shader =
+ create_shader_from_resource (GL_FRAGMENT_SHADER,
+ "/org/gnome/Retro/shaders/scanline.fs",
+ 0,
+ NULL);
// Prepare the shader program
shader_program = glCreateProgram();
@@ -165,6 +180,21 @@ retro_gl_display_unrealize (RetroGLDisplay *self)
self->shader_program = 0;
}
+static void
+set_gl_uniform_4f (GLuint program,
+ const GLchar *name,
+ GLfloat v0,
+ GLfloat v1,
+ GLfloat v2,
+ GLfloat v3)
+{
+
+ GLint location;
+
+ location = glGetUniformLocation (program, name);
+ glUniform4f (location, v0, v1, v2, v3);
+}
+
static gboolean
retro_gl_display_render (RetroGLDisplay *self)
{
@@ -174,6 +204,7 @@ retro_gl_display_render (RetroGLDisplay *self)
gdouble y = 0.0;
GLenum filter;
GLint relative_aspect_ratio;
+ GLfloat target_width, target_height, output_width, output_height;
g_return_val_if_fail (self != NULL, FALSE);
@@ -216,6 +247,19 @@ retro_gl_display_render (RetroGLDisplay *self)
(gfloat) gtk_widget_get_allocated_height (GTK_WIDGET (self)) /
self->aspect_ratio);
+ target_width = (GLfloat) gdk_pixbuf_get_width (self->pixbuf);
+ target_height = (GLfloat) gdk_pixbuf_get_height (self->pixbuf);
+ output_width = (GLfloat) gtk_widget_get_allocated_width (GTK_WIDGET (self));
+ output_height = (GLfloat) gtk_widget_get_allocated_height (GTK_WIDGET (self));
+
+ set_gl_uniform_4f (self->shader_program, "targetSize",
+ target_width, target_height,
+ 1.0f / target_width, 1.0f / target_height);
+
+ set_gl_uniform_4f (self->shader_program, "outputSize",
+ output_width, output_height,
+ 1.0f / output_width, 1.0f / output_height);
+
glDrawElements (GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
return FALSE;
diff --git a/retro-gtk/retro-gtk.gresource.xml b/retro-gtk/retro-gtk.gresource.xml
index e9a9c5f..5133261 100644
--- a/retro-gtk/retro-gtk.gresource.xml
+++ b/retro-gtk/retro-gtk.gresource.xml
@@ -3,5 +3,8 @@
<gresource prefix="/org/gnome/Retro">
<file>retro-gl-display-fragment.glsl</file>
<file>retro-gl-display-vertex.glsl</file>
+ <file>shaders/crt-simple.fs</file>
+ <file>shaders/crt-simple.vs</file>
+ <file>shaders/scanline.fs</file>
</gresource>
</gresources>
diff --git a/retro-gtk/shaders/crt-simple.fs b/retro-gtk/shaders/crt-simple.fs
new file mode 100644
index 0000000..5fdccaa
--- /dev/null
+++ b/retro-gtk/shaders/crt-simple.fs
@@ -0,0 +1,127 @@
+#version 150
+
+uniform sampler2D source[];
+uniform vec4 sourceSize[];
+
+in Vertex {
+ vec2 texCoord;
+ vec2 one;
+ float mod_factor;
+};
+
+out vec4 fragColor;
+
+ uniform vec4 targetSize;
+ uniform vec2 outputSize;
+
+ // Enable screen curvature.
+ #define CURVATURE
+
+ // Controls the intensity of the barrel distortion used to emulate the
+ // curvature of a CRT. 0.0 is perfectly flat, 1.0 is annoyingly
+ // distorted, higher values are increasingly ridiculous.
+ #define distortion 0.08
+
+ // Simulate a CRT gamma of 2.4.
+ #define inputGamma 2.4
+
+ // Compensate for the standard sRGB gamma of 2.2.
+ #define outputGamma 2.2
+
+ // Macros.
+ #define TEX2D(c) pow(texture2D(source[0], (c)), vec4(inputGamma))
+ #define PI 3.141592653589
+
+ // Apply radial distortion to the given coordinate.
+ vec2 radialDistortion(vec2 coord)
+ {
+ vec2 cc = coord - 0.5;
+ float dist = dot(cc, cc) * distortion;
+ return (coord + cc * (1.0 + dist) * dist);
+ }
+
+ // Calculate the influence of a scanline on the current pixel.
+ //
+ // 'distance' is the distance in texture coordinates from the current
+ // pixel to the scanline in question.
+ // 'color' is the colour of the scanline at the horizontal location of
+ // the current pixel.
+ vec4 scanlineWeights(float distance, vec4 color)
+ {
+ // The "width" of the scanline beam is set as 2*(1 + x^4) for
+ // each RGB channel.
+ vec4 wid = 2.0 + 2.0 * pow(color, vec4(4.0));
+
+ // The "weights" lines basically specify the formula that gives
+ // you the profile of the beam, i.e. the intensity as
+ // a function of distance from the vertical center of the
+ // scanline. In this case, it is gaussian if width=2, and
+ // becomes nongaussian for larger widths. Ideally this should
+ // be normalized so that the integral across the beam is
+ // independent of its width. That is, for a narrower beam
+ // "weights" should have a higher peak at the center of the
+ // scanline than for a wider beam.
+ vec4 weights = vec4(distance / 0.3);
+ return 1.4 * exp(-pow(weights * inversesqrt(0.5 * wid), wid)) / (0.6 + 0.2 * wid);
+ }
+
+void main() {
+ // Here's a helpful diagram to keep in mind while trying to
+ // understand the code:
+ //
+ // | | | | |
+ // -------------------------------
+ // | | | | |
+ // | 01 | 11 | 21 | 31 | <-- current scanline
+ // | | @ | | |
+ // -------------------------------
+ // | | | | |
+ // | 02 | 12 | 22 | 32 | <-- next scanline
+ // | | | | |
+ // -------------------------------
+ // | | | | |
+ //
+ // Each character-cell represents a pixel on the output
+ // surface, "@" represents the current pixel (always somewhere
+ // in the bottom half of the current scan-line, or the top-half
+ // of the next scanline). The grid of lines represents the
+ // edges of the texels of the underlying texture.
+
+ // Texture coordinates of the texel containing the active pixel.
+ #ifdef CURVATURE
+ vec2 xy = radialDistortion(texCoord);
+ #else
+ vec2 xy = texCoord;
+ #endif
+
+ // Of all the pixels that are mapped onto the texel we are
+ // currently rendering, which pixel are we currently rendering?
+ vec2 ratio_scale = xy * sourceSize[0].xy - vec2(0.5);
+ vec2 uv_ratio = fract(ratio_scale);
+
+ // Snap to the center of the underlying texel.
+ xy.y = (floor(ratio_scale.y) + 0.5) / sourceSize[0].y;
+
+ // Calculate the effective colour of the current and next
+ // scanlines at the horizontal location of the current pixel.
+ vec4 col = TEX2D(xy);
+ vec4 col2 = TEX2D(xy + vec2(0.0, one.y));
+
+ // Calculate the influence of the current and next scanlines on
+ // the current pixel.
+ vec4 weights = scanlineWeights(uv_ratio.y, col);
+ vec4 weights2 = scanlineWeights(1.0 - uv_ratio.y, col2);
+ vec3 mul_res = (col * weights + col2 * weights2).rgb;
+
+ // dot-mask emulation:
+ // Output pixels are alternately tinted green and magenta.
+ vec3 dotMaskWeights = mix(
+ vec3(1.0, 0.7, 1.0),
+ vec3(0.7, 1.0, 0.7),
+ floor(mod(mod_factor, 2.0))
+ );
+
+ mul_res *= dotMaskWeights;
+
+ fragColor = vec4(pow(mul_res, vec3(1.0 / outputGamma)), 1.0);
+}
diff --git a/retro-gtk/shaders/crt-simple.vs b/retro-gtk/shaders/crt-simple.vs
new file mode 100644
index 0000000..e1f50d5
--- /dev/null
+++ b/retro-gtk/shaders/crt-simple.vs
@@ -0,0 +1,27 @@
+#version 150
+
+in vec2 position;
+in vec2 texCoord;
+
+out Vertex {
+ vec2 texCoord;
+ // Define some calculations that will be used in fragment shader.
+ vec2 one;
+ float mod_factor;
+} vertexOut;
+
+ uniform vec4 targetSize;
+ uniform vec2 outputSize;
+ uniform vec4 sourceSize[];
+
+void main() {
+ gl_Position = vec4 (position, 0.0, 1.0);
+ vertexOut.texCoord = texCoord;
+
+
+ // The size of one texel, in texture-coordinates.
+ vertexOut.one = 1.0 / sourceSize[0].xy;
+
+ // Resulting X pixel-coordinate of the pixel we're drawing.
+ vertexOut.mod_factor = texCoord.x * targetSize.x;
+}
diff --git a/retro-gtk/shaders/scanline.fs b/retro-gtk/shaders/scanline.fs
new file mode 100644
index 0000000..42a9603
--- /dev/null
+++ b/retro-gtk/shaders/scanline.fs
@@ -0,0 +1,20 @@
+#version 150
+
+uniform sampler2D source[];
+
+in Vertex {
+ vec2 texCoord;
+};
+
+out vec4 fragColor;
+
+void main() {
+ vec4 rgba = texture(source[0], texCoord);
+ vec4 intensity;
+ if(fract(gl_FragCoord.y * (0.5 * 4.0 / 3.0)) > 0.5) {
+ intensity = vec4(0);
+ } else {
+ intensity = smoothstep(0.2, 0.8, rgba) + normalize(rgba);
+ }
+ fragColor = intensity * -0.25 + rgba * 1.1;
+}
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