From 630038754c1a9a04e05fc59bdbced17c06f3dab5 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Wed, 23 May 2018 20:16:09 +0200
Subject: Pass texture count to display fragment shader

---
 src/graphic_shader.h             |  6 ++++++
 src/main.cc                      |  9 ++++-----
 src/shader/display_fragment.glsl | 25 +++++--------------------
 src/texture_display_buffer.h     |  7 +------
 4 files changed, 16 insertions(+), 31 deletions(-)

diff --git a/src/graphic_shader.h b/src/graphic_shader.h
index c93e61b..c67dc01 100644
--- a/src/graphic_shader.h
+++ b/src/graphic_shader.h
@@ -38,6 +38,12 @@ public:
 		return id;
 	}
 
+	GLuint setUniform(const std::string& name, const std::vector<GLuint>& v) const {
+		GLuint id = util::getUniform(_id, name);
+		glUniform1iv(id, v.size(), reinterpret_cast<const GLint*>(v.data()));
+		return id;
+	}
+
 	GLuint setUniform(const std::string& name, glm::mat4& M) const {
 		GLuint id = util::getUniform(_id, name);
 		glUniformMatrix4fv(id, 1, GL_FALSE, &M[0][0]);
diff --git a/src/main.cc b/src/main.cc
index 034d026..ceffe67 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -22,9 +22,9 @@
 #include "shader/display_vertex.glsl"
 #include "shader/display_fragment.glsl"
 
-const unsigned int particle_count = 5000;
+const unsigned int particle_count = 1000;
 const unsigned int max_ups        = 100;
-const unsigned int texture_count  = 10;
+const unsigned int texture_count  = 20;
 
 unsigned int window_width  = 800;
 unsigned int window_height = 600;
@@ -173,9 +173,8 @@ int main() {
 		{
 			auto guard = displayShader.use();
 
-			for ( unsigned int i = 0; i < textures.size(); ++i ) {
-				displayShader.setUniform("screen_texture_" + std::to_string(i), i);
-			}
+			displayShader.setUniform("screen_textures",      textures);
+			displayShader.setUniform("screen_textures_size", textures.size());
 
 			glClear(GL_COLOR_BUFFER_BIT);
 
diff --git a/src/shader/display_fragment.glsl b/src/shader/display_fragment.glsl
index 03986a0..b731ebe 100644
--- a/src/shader/display_fragment.glsl
+++ b/src/shader/display_fragment.glsl
@@ -4,27 +4,12 @@ static const std::string DISPLAY_FRAGMENT_SHADER_CODE = R"(
 out vec4 FragColor;
 in vec2 TexCoords;
 
-uniform sampler2D screen_texture_0;
-uniform sampler2D screen_texture_1;
-uniform sampler2D screen_texture_2;
-uniform sampler2D screen_texture_3;
-uniform sampler2D screen_texture_4;
-uniform sampler2D screen_texture_5;
-uniform sampler2D screen_texture_6;
-uniform sampler2D screen_texture_7;
-uniform sampler2D screen_texture_8;
-uniform sampler2D screen_texture_9;
+uniform sampler2D screen_textures[64];
+uniform int screen_textures_size;
 
 void main() {
-	FragColor =       texture(screen_texture_0, TexCoords)
-	          + 0.9 * texture(screen_texture_1, TexCoords)
-	          + 0.8 * texture(screen_texture_2, TexCoords)
-	          + 0.7 * texture(screen_texture_3, TexCoords)
-	          + 0.6 * texture(screen_texture_4, TexCoords)
-	          + 0.5 * texture(screen_texture_5, TexCoords)
-	          + 0.4 * texture(screen_texture_6, TexCoords)
-	          + 0.3 * texture(screen_texture_7, TexCoords)
-	          + 0.2 * texture(screen_texture_8, TexCoords)
-	          + 0.1 * texture(screen_texture_9, TexCoords);
+	for ( int i = 0; i < screen_textures_size; ++i ) {
+		FragColor += (1.0 - i*1.0/screen_textures_size) * texture(screen_textures[i], TexCoords);
+	}
 }
 )";
diff --git a/src/texture_display_buffer.h b/src/texture_display_buffer.h
index 25fd319..b38f9c0 100644
--- a/src/texture_display_buffer.h
+++ b/src/texture_display_buffer.h
@@ -47,12 +47,7 @@ public:
 
 	void draw(const std::vector<GLuint>& textures) const {
 		glBindVertexArray(_array);
-
-		for ( unsigned int i = 0; i < textures.size(); ++i ) {
-			glActiveTexture(GL_TEXTURE0+i);
-			glBindTexture(GL_TEXTURE_2D, textures[i]);
-		}
-
+		glBindTextures(textures[0], textures.size(), textures.data());
 		glDrawArrays(GL_TRIANGLES, 0, 6);
 	}
 
-- 
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