Improve OpenGL performance by only calculating displacement textures when needed

It would appear that atm its setting a 1x1 grey texture which isn't too much of an issue, but I don't believe that works well. Let's try this.

Author: swagtoy

data/shader/shader100.frag

@@ -10,13 +10,14 @@ uniform float backbuffer;
 uniform float game_time;
 uniform vec2 animate;
 uniform vec2 displacement_animate;
+uniform bool is_displacement;
 
 varying vec2 texcoord_var;
 varying vec4 diffuse_var;
 
 void main(void)
 {
-  if (backbuffer == 0.0)
+  if (backbuffer == 0.0 || !is_displacement)
   {
     vec4 color = diffuse_var * texture2D(diffuse_texture, texcoord_var.st + (animate * game_time));
     gl_FragColor = color;

data/shader/shader330.frag

@@ -8,6 +8,7 @@ uniform float backbuffer;
 uniform float game_time;
 uniform vec2 animate;
 uniform vec2 displacement_animate;
+uniform bool is_displacement;
 
 in vec4 diffuse_var;
 in vec2 texcoord_var;
@@ -16,12 +17,12 @@ out vec4 fragColor;
 
 void main(void)
 {
-  if (backbuffer == 0.0)
+  if (backbuffer == 0.0 || !is_displacement)
   {
     vec4 color =  diffuse_var * texture(diffuse_texture, texcoord_var.st + (animate * game_time));
     fragColor = color;
   }
-  else if (true)
+  else if (is_displacement)
   {
     vec4 pixel = texture(displacement_texture, texcoord_var.st + (displacement_animate * game_time));
     vec2 displacement = (pixel.rg - vec2(0.5, 0.5)) * 255;
@@ -34,22 +35,6 @@ void main(void)
     vec4 color =  diffuse_var * texture(diffuse_texture, texcoord_var.st + (animate * game_time));
     fragColor = vec4(mix(color.rgb, back_color.rgb, alpha), color.a);
   }
-  else
-  {
-    // water reflection
-    vec4 color =  diffuse_var * texture(diffuse_texture, texcoord_var.st);
-    vec2 uv = (fragcoord2uv * gl_FragCoord.xyw).xy + vec2(0, 0.05);
-    uv.x = uv.x + 0.005 * sin(game_time + uv.y * 100);
-    uv = vec2(uv.x, 1.0 - uv.y);
-    vec4 back_color = texture(framebuffer_texture, uv);
-    if (backbuffer == 0.0)
-      fragColor = color;
-    else
-      if (uv.y > 0.5)
-        fragColor = vec4(mix(vec3(0,0,0.75), mix(color.rgb, back_color.rgb, 0.95 * backbuffer), (1.2 - uv.y) * (1.2 - uv.y)), 1.0);
-      else
-        fragColor = color;
-  }
 }
 
 /* EOF */

src/video/gl/gl33core_context.cpp

@@ -18,12 +18,14 @@
 
 #include "supertux/globals.hpp"
 #include "video/color.hpp"
+#include "video/gl.hpp"
 #include "video/gl/gl_program.hpp"
 #include "video/gl/gl_texture.hpp"
 #include "video/gl/gl_texture_renderer.hpp"
 #include "video/gl/gl_vertex_arrays.hpp"
 #include "video/gl/gl_video_system.hpp"
 #include "video/glutil.hpp"
+#include <iostream>
 
 GL33CoreContext::GL33CoreContext(GLVideoSystem& video_system) :
   m_video_system(video_system),
@@ -185,6 +187,7 @@ GL33CoreContext::bind_texture(const Texture& texture, const Texture* displacemen
   {
     glActiveTexture(GL_TEXTURE0);
     glBindTexture(GL_TEXTURE_2D, m_transparent_texture->get_handle());
+    glUniform1i(m_program->get_is_displacement_location(), true);
   }
   else
   {
@@ -197,6 +200,7 @@ GL33CoreContext::bind_texture(const Texture& texture, const Texture* displacemen
     animate.y /= static_cast<float>(texture.get_image_height());
 
     glUniform2f(m_program->get_animate_location(), animate.x, animate.y);
+    glUniform1i(m_program->get_is_displacement_location(), false);
   }
 
   if (displacement_texture)
@@ -210,11 +214,13 @@ GL33CoreContext::bind_texture(const Texture& texture, const Texture* displacemen
     animate.y /= static_cast<float>(displacement_texture->get_image_height());
 
     glUniform2f(m_program->get_displacement_animate_location(), animate.x, animate.y);
+    glUniform1i(m_program->get_is_displacement_location(), true);
   }
   else
   {
     glActiveTexture(GL_TEXTURE1);
     glBindTexture(GL_TEXTURE_2D, m_grey_texture->get_handle());
+    glUniform1i(m_program->get_is_displacement_location(), false);
   }
 
   assert_gl();

src/video/gl/gl_program.cpp

@@ -16,6 +16,7 @@
 
 #include "video/gl/gl_program.hpp"
 
+#include <iostream>
 #include <sstream>
 
 #include "video/glutil.hpp"
@@ -35,7 +36,8 @@ GLProgram::GLProgram() :
   m_displacement_animate_location(-1),
   m_position_location(-1),
   m_texcoord_location(-1),
-  m_diffuse_location(-1)
+  m_diffuse_location(-1),
+  m_is_displacement_location(-1)
 {
   assert_gl();
 
@@ -71,6 +73,7 @@ GLProgram::GLProgram() :
   m_modelviewprojection_location = glGetUniformLocation(m_program, "modelviewprojection");
   m_animate_location = glGetUniformLocation(m_program, "animate");
   m_displacement_animate_location = glGetUniformLocation(m_program, "displacement_animate");
+  m_is_displacement_location = glGetUniformLocation(m_program, "is_displacement");
   m_position_location = glGetAttribLocation(m_program, "position");
   m_texcoord_location = glGetAttribLocation(m_program, "texcoord");
   m_diffuse_location = glGetAttribLocation(m_program, "diffuse");

src/video/gl/gl_program.hpp

@@ -45,6 +45,7 @@ class GLProgram final
   inline GLint get_position_location() const { return check_valid(m_position_location, "position"); }
   inline GLint get_texcoord_location() const { return check_valid(m_texcoord_location, "texcoord"); }
   inline GLint get_diffuse_location() const { return check_valid(m_diffuse_location, "diffuse"); }
+  inline GLint get_is_displacement_location() const { return check_valid(m_is_displacement_location, "is_displacement"); }
 
 private:
   bool get_link_status() const;
@@ -70,6 +71,7 @@ class GLProgram final
   GLint m_position_location;
   GLint m_texcoord_location;
   GLint m_diffuse_location;
+  GLint m_is_displacement_location;
 
 private:
   GLProgram(const GLProgram&) = delete;