slideshow: Add shadows to the Vortex transition

These are done using a shadow mapping technique, we render both slides
from the point of view of the light, and then do a second pass in which
we lower the light of the fragment if some other cube is above it.

Change-Id: I8aaa1428c4481661283bf69b5e56aa4d95fb80dd
Reviewed-on: https://gerrit.libreoffice.org/22232
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Meeks <michael.meeks@collabora.com>

3 files changed, 76 insertions, 9 deletions

diff --git a/slideshow/opengl/vortexFragmentShader.glsl b/slideshow/opengl/vortexFragmentShader.glsl
new file mode 100644
index 000000000000..3212ebef7661
--- /dev/null
+++ b/slideshow/opengl/vortexFragmentShader.glsl
@@ -0,0 +1,34 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#version 150
+
+uniform sampler2D slideTexture;
+uniform sampler2D leavingShadowTexture;
+uniform sampler2D enteringShadowTexture;
+
+in vec2 v_texturePosition;
+in vec3 v_normal;
+in vec4 shadowCoordinate;
+
+void main() {
+    vec3 lightVector = vec3(0.0, 0.0, 1.0);
+    float light = max(dot(lightVector, v_normal), 0.0);
+    vec4 fragment = texture2D(slideTexture, v_texturePosition);
+    float visibility = 1.0;
+    const float epsilon = 0.0001;
+    if (texture2D(leavingShadowTexture, shadowCoordinate.xy).r < shadowCoordinate.z - epsilon)
+        visibility *= 0.7;
+    if (texture2D(enteringShadowTexture, shadowCoordinate.xy).r < shadowCoordinate.z - epsilon)
+        visibility *= 0.7;
+    vec4 black = vec4(0.0, 0.0, 0.0, fragment.a);
+    gl_FragColor = mix(black, fragment, visibility * light);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/slideshow/opengl/vortexGeometryShader.glsl b/slideshow/opengl/vortexGeometryShader.glsl
index 46999efad55f..312babac1c2f 100644
--- a/slideshow/opengl/vortexGeometryShader.glsl
+++ b/slideshow/opengl/vortexGeometryShader.glsl
@@ -14,16 +14,41 @@ layout(triangle_strip, max_vertices=11) out;
 
 in vec2 g_texturePosition[];
 in vec3 g_normal[];
+in mat4 projectionMatrix[];
 in mat4 modelViewMatrix[];
+in mat4 shadowMatrix[];
 in mat4 transform[];
 in float nTime[];
 in float startTime[];
 in float endTime[];
 
-uniform mat4 u_projectionMatrix;
-
 out vec2 v_texturePosition;
 out vec3 v_normal;
+out vec4 shadowCoordinate;
+
+mat4 identityMatrix(void)
+{
+    return mat4(1.0, 0.0, 0.0, 0.0,
+                0.0, 1.0, 0.0, 0.0,
+                0.0, 0.0, 1.0, 0.0,
+                0.0, 0.0, 0.0, 1.0);
+}
+
+mat4 scaleMatrix(vec3 axis)
+{
+    mat4 matrix = identityMatrix();
+    matrix[0][0] = axis.x;
+    matrix[1][1] = axis.y;
+    matrix[2][2] = axis.z;
+    return matrix;
+}
+
+mat4 translationMatrix(vec3 axis)
+{
+    mat4 matrix = identityMatrix();
+    matrix[3] = vec4(axis, 1.0);
+    return matrix;
+}
 
 void emitHexagonVertex(int index, vec3 translation, float fdsq)
 {
@@ -37,7 +62,8 @@ void emitHexagonVertex(int index, vec3 translation, float fdsq)
     v_normal = normalize(vec3(normalMatrix * transform[index] * vec4(g_normal[index], 0.0)));
     v_normal.z *= fdsq;
 
-    gl_Position = u_projectionMatrix * modelViewMatrix[index] * pos;
+    gl_Position = projectionMatrix[index] * modelViewMatrix[index] * pos;
+    shadowCoordinate = translationMatrix(vec3(0.5, 0.5, 0.5)) * scaleMatrix(vec3(0.5, 0.5, 0.5)) * shadowMatrix[index] * modelViewMatrix[index] * pos;
     v_texturePosition = g_texturePosition[index];
     EmitVertex();
 }
diff --git a/slideshow/opengl/vortexVertexShader.glsl b/slideshow/opengl/vortexVertexShader.glsl
index 603c62960f2a..9bab2d9e0397 100644
--- a/slideshow/opengl/vortexVertexShader.glsl
+++ b/slideshow/opengl/vortexVertexShader.glsl
@@ -16,6 +16,7 @@ in vec3 a_normal;
 in vec2 a_texCoord;
 in float tileInfo;
 
+uniform mat4 u_projectionMatrix;
 uniform mat4 u_modelViewMatrix;
 uniform mat4 u_sceneTransformMatrix;
 uniform mat4 u_primitiveTransformMatrix;
@@ -25,10 +26,15 @@ uniform float time;
 uniform ivec2 numTiles;
 uniform sampler2D permTexture;
 uniform float slide;
+uniform float shadow;
+uniform mat4 orthoProjectionMatrix;
+uniform mat4 orthoViewMatrix;
 
 out vec2 g_texturePosition;
 out vec3 g_normal;
+out mat4 projectionMatrix;
 out mat4 modelViewMatrix;
+out mat4 shadowMatrix;
 out mat4 transform;
 out float nTime;
 out float startTime;
@@ -134,13 +140,14 @@ void main( void )
                   * rotationMatrix(vec3(0.0, 1.0, 0.0), clamp(rotation, -1.0, 1.0) * M_PI)
                   * translationMatrix(-translationVector)
                   * transform;
+    }
 
-        // Add a translation movement to the leaving slide so it doesn’t exactly mirror the entering one.
-        if (isLeavingSlide && nTime > 0.3)
-        {
-            float movement = smoothstep(0.0, 1.0, (nTime - 0.3) * 2.0);
-            transform = translationMatrix(vec3(-movement, 0.0, -0.5 * movement)) * transform;
-        }
+    if (shadow < 0.5) {
+        projectionMatrix = u_projectionMatrix;
+        shadowMatrix = orthoProjectionMatrix * orthoViewMatrix;
+    } else {
+        projectionMatrix = orthoProjectionMatrix * orthoViewMatrix;
+        shadowMatrix = mat4(0.0);
     }
 
     modelViewMatrix = u_modelViewMatrix * u_operationsTransformMatrix * u_sceneTransformMatrix * u_primitiveTransformMatrix;