egutierrez
042bb43b37
- cpp/functions/gfx: gl_shader, gl_framebuffer, fullscreen_quad, shader_canvas - cpp/apps/shaders_lab: main + 3 seed shaders (plasma, circle, checker) - ImGui docking layout: Code | Canvas | Controls Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
86 lines
2.4 KiB
C++
86 lines
2.4 KiB
C++
#define GL_GLEXT_PROTOTYPES
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#include <GL/gl.h>
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#include <GL/glext.h>
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#include "gfx/shader_canvas.h"
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#include "imgui.h"
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namespace fn::gfx {
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void canvas_init(ShaderCanvas& c) {
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if (c.initialized) return;
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fb_init(c.fb);
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quad_init(c.quad);
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c.initialized = true;
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}
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void canvas_set_program(ShaderCanvas& c, unsigned int program) {
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if (c.program) delete_program(c.program);
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c.program = program;
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}
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void canvas_render(ShaderCanvas& c, float time_seconds) {
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ImVec2 avail = ImGui::GetContentRegionAvail();
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int w = static_cast<int>(avail.x);
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int h = static_cast<int>(avail.y);
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if (w < 1) w = 1;
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if (h < 1) h = 1;
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fb_resize(c.fb, w, h);
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// Save GL state
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GLint prev_fbo = 0;
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glGetIntegerv(GL_FRAMEBUFFER_BINDING, &prev_fbo);
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GLint prev_vp[4];
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glGetIntegerv(GL_VIEWPORT, prev_vp);
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// Render to FBO
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glBindFramebuffer(GL_FRAMEBUFFER, c.fb.fbo);
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glViewport(0, 0, w, h);
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glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
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glClear(GL_COLOR_BUFFER_BIT);
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if (c.program) {
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glUseProgram(c.program);
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GLint loc_res = glGetUniformLocation(c.program, "u_resolution");
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GLint loc_time = glGetUniformLocation(c.program, "u_time");
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GLint loc_mouse = glGetUniformLocation(c.program, "u_mouse");
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if (loc_res >= 0) glUniform2f(loc_res, static_cast<float>(w), static_cast<float>(h));
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if (loc_time >= 0) glUniform1f(loc_time, time_seconds);
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if (loc_mouse >= 0) {
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ImVec2 mouse = ImGui::GetMousePos();
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ImVec2 canvas_pos = ImGui::GetCursorScreenPos();
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// cursor pos is AFTER content region starts
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float mx = mouse.x - canvas_pos.x;
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float my = static_cast<float>(h) - (mouse.y - canvas_pos.y);
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glUniform2f(loc_mouse, mx, my);
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}
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quad_draw(c.quad);
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glUseProgram(0);
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}
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// Restore GL state
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glBindFramebuffer(GL_FRAMEBUFFER, static_cast<GLuint>(prev_fbo));
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glViewport(prev_vp[0], prev_vp[1], prev_vp[2], prev_vp[3]);
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// Draw texture in ImGui panel (flip V: OpenGL origin is bottom-left)
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ImGui::Image(
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(ImTextureID)(intptr_t)c.fb.tex,
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avail,
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ImVec2(0, 1), ImVec2(1, 0)
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);
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}
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void canvas_destroy(ShaderCanvas& c) {
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if (!c.initialized) return;
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if (c.program) { delete_program(c.program); c.program = 0; }
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quad_destroy(c.quad);
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fb_destroy(c.fb);
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c.initialized = false;
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}
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} // namespace fn::gfx
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