setup simple 2d rendering pipeline

examples/charts/Makefile.am

@@ -1,4 +1,4 @@
 noinst_PROGRAMS = example_linechart
 
 example_linechart_SOURCES = linechart.cc
-example_linechart_LDADD = -lshowtime
+example_linechart_LDADD = -lshowtime -lX11 -lGL -lglfw -lGLEW

examples/charts/linechart.cc

@@ -8,6 +8,7 @@
  * <http://www.gnu.org/licenses/>.
  */
 #include <iostream>
+#include <unistd.h>
 #include <showtime/showtime.h>
 #include "showtime/extra/chart/axisdefinition.h"
 #include "showtime/extra/chart/areachart.h"
@@ -17,7 +18,11 @@
 #include "showtime/extra/chart/linechart.h"
 #include "showtime/extra/chart/pointchart.h"
 #include "showtime/extra/chart/series.h"
-#include "showtime/graphics/layer_svg.h"
+#include "showtime/graphics/canvas_svg.h"
+#include "showtime/platform/opengl/opengl_context.h"
+#include "showtime/platform/opengl/canvas_opengl.h"
+#include "showtime/platform/x11/image_display.h"
+
 
 using namespace cplot;
 
@@ -51,11 +56,21 @@ int main() {
   line_chart->addAxis(AxisDefinition::BOTTOM);
   line_chart->addAxis(AxisDefinition::LEFT);
 
-  std::string svg;
-  SVGTarget target(&svg);
+  std::unique_ptr<showtime::opengl::GLContext> ctx;
+  {
+    auto rc = showtime::opengl::GLContext::createWindow(&ctx);
+    if (!rc.isSuccess()) {
+      std::cerr << "ERROR: " << rc.getMessage() << std::endl;
+      return EXIT_FAILURE;
+    }
+  }
+
+  showtime::opengl::Canvas2D target(ctx.get());
   canvas.render(&target);
+  target.flush();
 
-  std::cout << svg << std::endl;
+  ctx->swap();
+  ::usleep(5 * 1000 * 1000);
 
   return 0;
 }

src/showtime/Makefile.am

@@ -34,9 +34,17 @@ libshowtime_a_SOURCES = \
     extra/chart/timedomain.cc \
     extra/chart/timedomain.h \
     extra/chart/viewport.h \
+    graphics/camera.h \
+    graphics/camera.cc \
     graphics/canvas.h \
     graphics/canvas.cc \
     graphics/canvas_svg.h \
+    platform/opengl/canvas_opengl.h \
+    platform/opengl/canvas_opengl.cc \
+    platform/opengl/opengl_context.h \
+    platform/opengl/opengl_context.cc \
+    platform/opengl/opengl_shader.h \
+    platform/opengl/opengl_shader.cc \
     platform/x11/image_display.h \
     platform/x11/image_display.cc \
     showtime.h \
@@ -55,4 +63,6 @@ libshowtime_a_SOURCES = \
     util/stringutil.h \
     util/stringutil.cc \
     util/time.h \
-    util/time.cc
+    util/time.cc \
+    util/vmath.h \
+    util/vmath.cc

core/plg/scene/Camera.cpp → src/showtime/graphics/camera.cc

@@ -12,9 +12,38 @@
 #include <string.h>
 #include <cstdio>
 #include <math.h>
-#include <plg.h>
-#include <plg/vmath.h>
-#include <plg/scene/Camera.h>
+#include "showtime/graphics/camera.h"
+
+namespace showtime {
+
+// http://en.wikipedia.org/wiki/Orthographic_projection_(geometry)
+mat4 Camera::getOrthoProjectionMatrix(
+    float left,
+    float right,
+    float top,
+    float bottom,
+    float near,
+    float far) {
+  mat4 mat;
+  auto m = (float*) &mat;
+  m[0x0] = 2.0f * (1.0f / (right - left));
+  m[0x1] = 0.0f;
+  m[0x2] = 0.0f;
+  m[0x3] = 0.0f;
+  m[0x4] = 0.0f;
+  m[0x5] = 2.0 * (1.0f / (top - bottom));
+  m[0x6] = 0.0f;
+  m[0x7] = 0.0f;
+  m[0x8] = 0.0f;
+  m[0x9] = 0.0f;
+  m[0xa] = -2.0f * (1.0f / (far - near));
+  m[0xb] = 0.0f;
+  m[0xc] = -(right + left) * (1.0f / (right - left));
+  m[0xd] = -(top + bottom) * (1.0f / (top - bottom));
+  m[0xe] = -(far + near) * (1.0f / (far - near));
+  m[0xf] = 1.0f;
+  return mat;
+}
 
 /**
  * For extended documentation see "Camera.h"
@@ -47,11 +76,6 @@ Camera::Camera() {
 Camera::~Camera() {
 }
 
-void Camera::activate() {
-  Frame* frame = PLG_CURRENT_FRAME;
-  frame->setCamera(this);
-}
-
 vec3* Camera::getWorldPosition() {
   return &w_pos_;
 }
@@ -152,3 +176,5 @@ void Camera::mkViewMatrix() {
   view_mat_ver_++;
 }
 
+} // namespace showtime
+

core/plg/scene/Camera.h → src/showtime/graphics/camera.h

@@ -8,10 +8,10 @@
  * copy of the GNU General Public License along with this program. If not, see
  * <http://www.gnu.org/licenses/>.
  */
-#include <plg/vmath.h>
+#pragma once
+#include "showtime/util/vmath.h"
 
-#ifndef CAMERA_H
-#define CAMERA_H
+namespace showtime {
 
 /**
  * The camera class. For a first person perspective the local position should
@@ -37,6 +37,16 @@ class Camera {
 
 public:
 
+  // Returns an orthographic projection matrix
+  // http://en.wikipedia.org/wiki/Orthographic_projection_(geometry)
+  static mat4 getOrthoProjectionMatrix(
+      float clip_left,
+      float clip_right,
+      float clip_top,
+      float clip_bottom,
+      float near,
+      float far);
+
   /**
    * Initialize a new camera
    */
@@ -47,12 +57,6 @@ class Camera {
    */
   ~Camera();
 
-  /**
-   * Make this camera the active camera for the current frame. Must be called
-   * on every frame!
-   */
-  void activate();
-
   /**
    * Get the world position of this camera (translation applied after rotation)
    */
@@ -123,5 +127,5 @@ class Camera {
 
 };
 
+} // namespace showtime
 
-#endif

src/showtime/platform/opengl/canvas_opengl.cc

@@ -7,8 +7,11 @@
  * copy of the GNU General Public License along with this program. If not, see
  * <http://www.gnu.org/licenses/>.
  */
+#include <iostream>
+#include "showtime/graphics/camera.h"
 #include "showtime/platform/opengl/canvas_opengl.h"
 #include "showtime/platform/opengl/opengl_context.h"
+#include "showtime/platform/opengl/opengl_shader.h"
 
 namespace showtime {
 namespace opengl {
@@ -27,7 +30,7 @@ static const std::string kFragmentShader = R"(
 #version 400
 out vec4 frag_colour;
 void main() {
-  frag_colour = vec4(1.0, 1.0, 1.0, 1.0);
+  frag_colour = vec4(0.0, 0.0, 0.0, 1.0);
 }
 )";
 
@@ -95,6 +98,8 @@ void Canvas2D::flush() {
       50.0f,  200.0f,  0.0f
   };
 
+  mat4 orthomatrix = showtime::Camera::getOrthoProjectionMatrix(0, 1300, 0, 600, -1, 1);
+
   ctx_->activate();
 
   // FIXME reuse vbo
@@ -116,30 +121,38 @@ void Canvas2D::flush() {
   glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
 
   // FIXME reuse shaders
-  GLuint vs = glCreateShader(GL_VERTEX_SHADER);
-  {
-    auto shader_src = kVertexShader.c_str();
-    glShaderSource(vs, 1, &shader_src, NULL);
-    glCompileShader(vs);
+  GLShaderBuilder shader_builder;
+  if (!shader_builder.addVertexShader(kVertexShader)){
+    std::cerr << "cant' build vertex shader" << std::endl;
+    return;
   }
 
-  GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
-  {
-    auto shader_src = kFragmentShader.c_str();
-    glShaderSource(fs, 1, &shader_src, NULL);
-    glCompileShader(fs);
+  if (!shader_builder.addFragmentShader(kFragmentShader)){
+    std::cerr << "cant' build fragment shader" << std::endl;
+    return;
   }
 
-  GLuint shader_programme = glCreateProgram();
-  glAttachShader(shader_programme, fs);
-  glAttachShader(shader_programme, vs);
-  glLinkProgram(shader_programme);
+  auto shader = shader_builder.link();
+  if (!shader) {
+    std::cerr << "cant' build fragment shader" << std::endl;
+    return;
+  }
 
   /* draw */
+  glClearColor(1.0, 1.0, 1.0, 1.0);
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  glUseProgram(shader_programme);
+
+  shader.get().activate();
+  auto loc = shader.get().getUniformLocation("in_proj");
+  if (!loc) {
+    std::cerr << "cant find in_proj: " << loc.getMessage() << std::endl;
+    return;
+  }
+
+  shader.get().setUniform(loc.get(), orthomatrix);
+
   glBindVertexArray(vao);
-  glDrawArrays(GL_TRIANGLES, 0, drawbuf_.size() / 3);
+  glDrawArrays(GL_TRIANGLES, 0, 3);
 
   drawbuf_.clear();
 }

src/showtime/platform/opengl/opengl_context.cc

@@ -17,7 +17,7 @@ ReturnCode GLContext::createWindow(std::unique_ptr<GLContext>* context) {
   uint32_t window_height = 600;
 
   if (!glfwInit()) {
-    return ReturnCode::error("EIO", "ERROR: glfw_init() failed");
+    return ReturnCode::error("ERROR: glfw_init() failed");
   }
 
   glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
@@ -29,14 +29,14 @@ ReturnCode GLContext::createWindow(std::unique_ptr<GLContext>* context) {
 
   auto window = glfwCreateWindow(window_width, window_height, "linechart", NULL, NULL);
   if (!window){
-    return ReturnCode::error("EIO", "ERROR: glfwCreateWindow() failed");
+    return ReturnCode::error("ERROR: glfwCreateWindow() failed");
   }
 
   glfwMakeContextCurrent(window);
 
   glewExperimental = true;
   if (glewInit() != GLEW_OK) {
-    return ReturnCode::error("EIO", "ERROR: glew_init failed() failed");
+    return ReturnCode::error("ERROR: glew_init failed() failed");
   }
 
   context->reset(new GLContext(window));